[PATCH v4 00/13] drm: Support short-term vmap via vmap_local

STALE2049d

Revision v4 of 2 in this series.

29 messages, 2 authors, 2021-02-02 · open the first message on its own page

[PATCH v4 00/13] drm: Support short-term vmap via vmap_local

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:44:29 

GEM VRAM helpers used to pin the BO in their implementation of vmap, so
that they could not be relocated. In recent discussions, [1][2] it became
clear that this is incorrect for in-kernel use cases, such as fbdev
emulation; which should rather depend on the reservation lock to prevent
relocation.

This patchset addresses the issue by introducing the new interfaces
vmap_local and vunmap_local throughout dma-buf and GEM. It further adds
support to DRM's CMA, SHMEM and VRAM helpers and finally converts fbdev
emulation to the new interface.

Patches 1 and 2 add the vmap_local infrastructure throughout dma-buf,
GEM and PRIME.

Patches 3 to 11 add implementations of vmap_local to DRM's various GEM
helper libraries. Due to the simple nature of these libraries, existing
vmap code can be reused easily. Several drivers are updated as well to
use the new interfaces.

Patch 12 converts generic fbdev emulation to use vmap_local. Only DRM
drivers that use GEM helpers currently use fbdev emulation, so patches
3 to 11 covered all necessary instances.

Finally patch 13 removes drm_gem_vram_vmap() functionality, which is now
unused.

I smoke-tested the patchset with ast (VRAM helpers), mgag200 (SHMEM) and
vc4 (CMA). I also tested with a version of radeon (raw TTM) that had been
converted to generic fbdev emulation.

v4:
	* move driver changes out of SHMEM and VRAM patches (Daniel)
	* call dma_buf_vmap_local() in SHMEM implementation (Daniel)
	* remove unused drm_gem_vram_vmap() functionality
	* update documentation (Daniel)
v3:
	* rewrite patchset around vmap_local
v2:
	* make importers acquire resv locks by themselves
	* document dma-buf vmap/vunmap ops

[1] https://patchwork.freedesktop.org/patch/400054/?series=83765&rev=1
[2] https://patchwork.freedesktop.org/patch/405407/?series=84401&rev=2

Thomas Zimmermann (13):
  dma-buf: Add vmap_local and vnumap_local operations
  drm/gem: Create infrastructure for GEM vmap_local
  drm/cma-helper: Provide a vmap function for short-term mappings
  drm/shmem-helper: Provide a vmap function for short-term mappings
  drm/mgag200: Use drm_gem_shmem_vmap_local() in damage handling
  drm/cirrus: Use drm_gem_shmem_vmap_local() in damage handling
  drm/gm12u320: Use drm_gem_shmem_vmap_local() in damage handling
  drm/udl: Use drm_gem_shmem_vmap_local() in damage handling
  drm/vram-helper: Provide a vmap function for short-term mappings
  drm/ast: Use drm_gem_vram_vmap_local() in cursor update
  drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update
  drm/fb-helper: Move BO locking from DRM client to fbdev damage worker
  drm/vram-helper: Remove unused drm_gem_vram_{vmap,vunmap}()

 drivers/dma-buf/dma-buf.c              |  81 ++++++++++++++
 drivers/gpu/drm/ast/ast_cursor.c       |  37 +++++--
 drivers/gpu/drm/drm_client.c           |  94 +++++++++++++++++
 drivers/gpu/drm/drm_fb_helper.c        |  41 ++++----
 drivers/gpu/drm/drm_gem.c              |  28 +++++
 drivers/gpu/drm/drm_gem_cma_helper.c   |  27 +++++
 drivers/gpu/drm/drm_gem_shmem_helper.c |  90 ++++++++++++++--
 drivers/gpu/drm/drm_gem_vram_helper.c  | 139 ++++++++-----------------
 drivers/gpu/drm/drm_internal.h         |   2 +
 drivers/gpu/drm/drm_prime.c            |  39 +++++++
 drivers/gpu/drm/mgag200/mgag200_mode.c |  16 ++-
 drivers/gpu/drm/tiny/cirrus.c          |  10 +-
 drivers/gpu/drm/tiny/gm12u320.c        |  14 ++-
 drivers/gpu/drm/udl/udl_modeset.c      |  18 ++--
 drivers/gpu/drm/vboxvideo/vbox_mode.c  |  15 +--
 drivers/gpu/drm/vc4/vc4_bo.c           |   1 +
 drivers/gpu/drm/virtio/virtgpu_prime.c |   2 +
 include/drm/drm_client.h               |   4 +
 include/drm/drm_gem.h                  |  21 ++++
 include/drm/drm_gem_cma_helper.h       |   1 +
 include/drm/drm_gem_shmem_helper.h     |   2 +
 include/drm/drm_gem_vram_helper.h      |   4 +-
 include/drm/drm_prime.h                |   2 +
 include/linux/dma-buf.h                |  34 ++++++
 24 files changed, 566 insertions(+), 156 deletions(-)

--
2.29.2

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[PATCH v4 02/13] drm/gem: Create infrastructure for GEM vmap_local

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:44:29 

This patch adds vmap_local and vunmap_local to struct drm_gem_object_funcs;
including the PRIME helpers to connect with dma-buf's related interfaces.

Besides the generic DRM core, this will become relevant for fbdev emulation
with virtio, so we update it as well.

v4:
	* update documentation (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
---
 drivers/gpu/drm/drm_gem.c              | 28 ++++++++++++++++++
 drivers/gpu/drm/drm_internal.h         |  2 ++
 drivers/gpu/drm/drm_prime.c            | 39 ++++++++++++++++++++++++++
 drivers/gpu/drm/virtio/virtgpu_prime.c |  2 ++
 include/drm/drm_gem.h                  | 21 ++++++++++++++
 include/drm/drm_prime.h                |  2 ++
 6 files changed, 94 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c
index 92f89cee213e..6e131d9bb7bd 100644
--- a/drivers/gpu/drm/drm_gem.c
+++ b/drivers/gpu/drm/drm_gem.c
@@ -1234,6 +1234,34 @@ void drm_gem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 	dma_buf_map_clear(map);
 }
 
+int drm_gem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	int ret;
+
+	if (!obj->funcs->vmap_local)
+		return -EOPNOTSUPP;
+
+	ret = obj->funcs->vmap_local(obj, map);
+	if (ret)
+		return ret;
+	else if (dma_buf_map_is_null(map))
+		return -ENOMEM;
+
+	return 0;
+}
+
+void drm_gem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	if (dma_buf_map_is_null(map))
+		return;
+
+	if (obj->funcs->vunmap_local)
+		obj->funcs->vunmap_local(obj, map);
+
+	/* Always set the mapping to NULL. Callers may rely on this. */
+	dma_buf_map_clear(map);
+}
+
 /**
  * drm_gem_lock_reservations - Sets up the ww context and acquires
  * the lock on an array of GEM objects.
diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 81d386b5b92a..b0bf6aba763a 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -190,6 +190,8 @@ int drm_gem_pin(struct drm_gem_object *obj);
 void drm_gem_unpin(struct drm_gem_object *obj);
 int drm_gem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
 void drm_gem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 
 /* drm_debugfs.c drm_debugfs_crc.c */
 #if defined(CONFIG_DEBUG_FS)
diff --git a/drivers/gpu/drm/drm_prime.c b/drivers/gpu/drm/drm_prime.c
index 683aa29ecd3b..633edea76985 100644
--- a/drivers/gpu/drm/drm_prime.c
+++ b/drivers/gpu/drm/drm_prime.c
@@ -695,6 +695,43 @@ void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct dma_buf_map *map)
 }
 EXPORT_SYMBOL(drm_gem_dmabuf_vunmap);
 
+/**
+ * drm_gem_dmabuf_vmap_local - dma_buf vmap_local implementation for GEM
+ * @dma_buf: buffer to be mapped
+ * @map: the virtual address of the buffer
+ *
+ * Sets up a kernel virtual mapping. This can be used as the &dma_buf_ops.vmap_local
+ * callback. Calls into &drm_gem_object_funcs.vmap_local for device specific handling.
+ * The kernel virtual address is returned in map.
+ *
+ * Returns:
+ * 0 on success or a negative errno code otherwise.
+ */
+int drm_gem_dmabuf_vmap_local(struct dma_buf *dma_buf, struct dma_buf_map *map)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	return drm_gem_vmap_local(obj, map);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_vmap_local);
+
+/**
+ * drm_gem_dmabuf_vunmap_local - dma_buf vunmap_local implementation for GEM
+ * @dma_buf: buffer to be unmapped
+ * @map: the virtual address of the buffer
+ *
+ * Releases a kernel virtual mapping. This can be used as the
+ * &dma_buf_ops.vunmap_local callback. Calls into &drm_gem_object_funcs.vunmap_local
+ * for device specific handling.
+ */
+void drm_gem_dmabuf_vunmap_local(struct dma_buf *dma_buf, struct dma_buf_map *map)
+{
+	struct drm_gem_object *obj = dma_buf->priv;
+
+	drm_gem_vunmap_local(obj, map);
+}
+EXPORT_SYMBOL(drm_gem_dmabuf_vunmap_local);
+
 /**
  * drm_gem_prime_mmap - PRIME mmap function for GEM drivers
  * @obj: GEM object
@@ -787,6 +824,8 @@ static const struct dma_buf_ops drm_gem_prime_dmabuf_ops =  {
 	.mmap = drm_gem_dmabuf_mmap,
 	.vmap = drm_gem_dmabuf_vmap,
 	.vunmap = drm_gem_dmabuf_vunmap,
+	.vmap_local = drm_gem_dmabuf_vmap_local,
+	.vunmap_local = drm_gem_dmabuf_vunmap_local,
 };
 
 /**
diff --git a/drivers/gpu/drm/virtio/virtgpu_prime.c b/drivers/gpu/drm/virtio/virtgpu_prime.c
index 807a27a16365..fea11a53d8fc 100644
--- a/drivers/gpu/drm/virtio/virtgpu_prime.c
+++ b/drivers/gpu/drm/virtio/virtgpu_prime.c
@@ -54,6 +54,8 @@ static const struct virtio_dma_buf_ops virtgpu_dmabuf_ops =  {
 		.mmap = drm_gem_dmabuf_mmap,
 		.vmap = drm_gem_dmabuf_vmap,
 		.vunmap = drm_gem_dmabuf_vunmap,
+		.vmap = drm_gem_dmabuf_vmap_local,
+		.vunmap = drm_gem_dmabuf_vunmap_local,
 	},
 	.device_attach = drm_gem_map_attach,
 	.get_uuid = virtgpu_virtio_get_uuid,
diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h
index 5e6daa1c982f..1b4425dd1596 100644
--- a/include/drm/drm_gem.h
+++ b/include/drm/drm_gem.h
@@ -151,6 +151,27 @@ struct drm_gem_object_funcs {
 	 */
 	void (*vunmap)(struct drm_gem_object *obj, struct dma_buf_map *map);
 
+	/**
+	 * @vmap_local:
+	 *
+	 * Returns a virtual address for the buffer. Used by the
+	 * drm_gem_dmabuf_vmap_local() helper. Callers will hold &drm_gem_object.resv
+	 * already and only release it after @vunmap_local has been called.
+	 *
+	 * This callback is optional.
+	 */
+	int (*vmap_local)(struct drm_gem_object *obj, struct dma_buf_map *map);
+
+	/**
+	 * @vunmap_local:
+	 *
+	 * Releases the address previously returned by @vmap. Used by the
+	 * drm_gem_dmabuf_vunmap_local() helper.
+	 *
+	 * This callback is optional.
+	 */
+	void (*vunmap_local)(struct drm_gem_object *obj, struct dma_buf_map *map);
+
 	/**
 	 * @mmap:
 	 *
diff --git a/include/drm/drm_prime.h b/include/drm/drm_prime.h
index 54f2c58305d2..fd2aef6966ef 100644
--- a/include/drm/drm_prime.h
+++ b/include/drm/drm_prime.h
@@ -85,6 +85,8 @@ void drm_gem_unmap_dma_buf(struct dma_buf_attachment *attach,
 			   enum dma_data_direction dir);
 int drm_gem_dmabuf_vmap(struct dma_buf *dma_buf, struct dma_buf_map *map);
 void drm_gem_dmabuf_vunmap(struct dma_buf *dma_buf, struct dma_buf_map *map);
+int drm_gem_dmabuf_vmap_local(struct dma_buf *dma_buf, struct dma_buf_map *map);
+void drm_gem_dmabuf_vunmap_local(struct dma_buf *dma_buf, struct dma_buf_map *map);
 
 int drm_gem_prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
 int drm_gem_dmabuf_mmap(struct dma_buf *dma_buf, struct vm_area_struct *vma);
-- 
2.29.2

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[PATCH v4 01/13] dma-buf: Add vmap_local and vnumap_local operations

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:44:30 

The existing dma-buf calls dma_buf_vmap() and dma_buf_vunmap() are
allowed to pin the buffer or acquire the buffer's reservation object
lock.

This is a problem for callers that only require a short-term mapping
of the buffer without the pinning, or callers that have special locking
requirements. These may suffer from unnecessary overhead or interfere
with regular pin operations.

The new interfaces dma_buf_vmap_local(), dma_buf_vunmapo_local(), and
their rsp callbacks in struct dma_buf_ops provide an alternative without
pinning or reservation locking. Callers are responsible for these
operations.

v4:
	* update documentation (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
Suggested-by: Daniel Vetter <redacted>
---
 drivers/dma-buf/dma-buf.c | 81 +++++++++++++++++++++++++++++++++++++++
 include/linux/dma-buf.h   | 34 ++++++++++++++++
 2 files changed, 115 insertions(+)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index b8465243eca2..01f9c74d97fa 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -1295,6 +1295,87 @@ void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map)
 }
 EXPORT_SYMBOL_GPL(dma_buf_vunmap);
 
+/**
+ * dma_buf_vmap_local - Create virtual mapping for the buffer object into kernel
+ * address space.
+ * @dmabuf:	[in]	buffer to vmap
+ * @map:	[out]	returns the vmap pointer
+ *
+ * Unlike dma_buf_vmap() this is a short term mapping and will not pin
+ * the buffer. The struct dma_resv for the @dmabuf must be locked until
+ * dma_buf_vunmap_local() is called.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int dma_buf_vmap_local(struct dma_buf *dmabuf, struct dma_buf_map *map)
+{
+	struct dma_buf_map ptr;
+	int ret = 0;
+
+	dma_buf_map_clear(map);
+
+	if (WARN_ON(!dmabuf))
+		return -EINVAL;
+
+	dma_resv_assert_held(dmabuf->resv);
+
+	if (!dmabuf->ops->vmap_local)
+		return -EINVAL;
+
+	mutex_lock(&dmabuf->lock);
+	if (dmabuf->vmapping_counter) {
+		dmabuf->vmapping_counter++;
+		BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr));
+		*map = dmabuf->vmap_ptr;
+		goto out_unlock;
+	}
+
+	BUG_ON(dma_buf_map_is_set(&dmabuf->vmap_ptr));
+
+	ret = dmabuf->ops->vmap_local(dmabuf, &ptr);
+	if (WARN_ON_ONCE(ret))
+		goto out_unlock;
+
+	dmabuf->vmap_ptr = ptr;
+	dmabuf->vmapping_counter = 1;
+
+	*map = dmabuf->vmap_ptr;
+
+out_unlock:
+	mutex_unlock(&dmabuf->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(dma_buf_vmap_local);
+
+/**
+ * dma_buf_vunmap_local - Unmap a vmap obtained by dma_buf_vmap_local.
+ * @dmabuf:	[in]	buffer to vunmap
+ * @map:	[in]	vmap pointer to vunmap
+ *
+ * Release a mapping established with dma_buf_vmap_local().
+ */
+void dma_buf_vunmap_local(struct dma_buf *dmabuf, struct dma_buf_map *map)
+{
+	if (WARN_ON(!dmabuf))
+		return;
+
+	dma_resv_assert_held(dmabuf->resv);
+
+	BUG_ON(dma_buf_map_is_null(&dmabuf->vmap_ptr));
+	BUG_ON(dmabuf->vmapping_counter == 0);
+	BUG_ON(!dma_buf_map_is_equal(&dmabuf->vmap_ptr, map));
+
+	mutex_lock(&dmabuf->lock);
+	if (--dmabuf->vmapping_counter == 0) {
+		if (dmabuf->ops->vunmap_local)
+			dmabuf->ops->vunmap_local(dmabuf, map);
+		dma_buf_map_clear(&dmabuf->vmap_ptr);
+	}
+	mutex_unlock(&dmabuf->lock);
+}
+EXPORT_SYMBOL_GPL(dma_buf_vunmap_local);
+
 #ifdef CONFIG_DEBUG_FS
 static int dma_buf_debug_show(struct seq_file *s, void *unused)
 {
diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h
index 628681bf6c99..aeed754b5467 100644
--- a/include/linux/dma-buf.h
+++ b/include/linux/dma-buf.h
@@ -264,6 +264,38 @@ struct dma_buf_ops {
 
 	int (*vmap)(struct dma_buf *dmabuf, struct dma_buf_map *map);
 	void (*vunmap)(struct dma_buf *dmabuf, struct dma_buf_map *map);
+
+	/**
+	 * @vmap_local:
+	 *
+	 * Creates a virtual mapping for the buffer into kernel address space.
+	 *
+	 * This callback establishes short-term mappings for situations where
+	 * callers only use the buffer for a bounded amount of time; such as
+	 * updates to the framebuffer or reading back contained information.
+	 * In contrast to the regular @vmap callback, vmap_local does never pin
+	 * the buffer to a specific domain or acquire the buffer's reservation
+	 * lock.
+	 *
+	 * This is called with the &dma_buf.resv object locked. Callers must hold
+	 * the lock until after removing the mapping with @vunmap_local.
+	 *
+	 * This callback is optional.
+	 *
+	 * Returns:
+	 *
+	 * 0 on success or a negative error code on failure.
+	 */
+	int (*vmap_local)(struct dma_buf *dmabuf, struct dma_buf_map *map);
+
+	/**
+	 * @vunmap_local:
+	 *
+	 * Removes a virtual mapping that was established by @vmap_local.
+	 *
+	 * This callback is optional.
+	 */
+	void (*vunmap_local)(struct dma_buf *dmabuf, struct dma_buf_map *map);
 };
 
 /**
@@ -501,4 +533,6 @@ int dma_buf_mmap(struct dma_buf *, struct vm_area_struct *,
 		 unsigned long);
 int dma_buf_vmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
 void dma_buf_vunmap(struct dma_buf *dmabuf, struct dma_buf_map *map);
+int dma_buf_vmap_local(struct dma_buf *dmabuf, struct dma_buf_map *map);
+void dma_buf_vunmap_local(struct dma_buf *dmabuf, struct dma_buf_map *map);
 #endif /* __DMA_BUF_H__ */
-- 
2.29.2

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[PATCH v4 03/13] drm/cma-helper: Provide a vmap function for short-term mappings

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:44:31 

Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private CMA buffers, but may happen
with imported ones.

Therefore provide the new interface drm_gem_cma_vmap_local(), which only
performs the vmap operations. Callers have to hold the reservation lock
while the mapping persists.

This patch also connects GEM CMA helpers to the GEM object function with
equivalent functionality.

v4:
	* vc4: don't wrap drm_gem_cma_vmap_local() in BO funcs (Daniel)
	* remove the TODO comment (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
---
 drivers/gpu/drm/drm_gem_cma_helper.c | 27 +++++++++++++++++++++++++++
 drivers/gpu/drm/vc4/vc4_bo.c         |  1 +
 include/drm/drm_gem_cma_helper.h     |  1 +
 3 files changed, 29 insertions(+)

diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c
index 7942cf05cd93..f854027fa01f 100644
--- a/drivers/gpu/drm/drm_gem_cma_helper.c
+++ b/drivers/gpu/drm/drm_gem_cma_helper.c
@@ -38,6 +38,7 @@ static const struct drm_gem_object_funcs drm_gem_cma_default_funcs = {
 	.print_info = drm_gem_cma_print_info,
 	.get_sg_table = drm_gem_cma_get_sg_table,
 	.vmap = drm_gem_cma_vmap,
+	.vmap_local = drm_gem_cma_vmap_local,
 	.mmap = drm_gem_cma_mmap,
 	.vm_ops = &drm_gem_cma_vm_ops,
 };
@@ -471,6 +472,32 @@ int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 }
 EXPORT_SYMBOL_GPL(drm_gem_cma_vmap);
 
+/**
+ * drm_gem_cma_vmap_local - map a CMA GEM object into the kernel's virtual
+ *     address space
+ * @obj: GEM object
+ * @map: Returns the kernel virtual address of the CMA GEM object's backing
+ *       store.
+ *
+ * This function maps a buffer into the kernel's
+ * virtual address space. Since the CMA buffers are already mapped into the
+ * kernel virtual address space this simply returns the cached virtual
+ * address. Drivers using the CMA helpers should set this as their DRM
+ * driver's &drm_gem_object_funcs.vmap_local callback.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_gem_cma_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(obj);
+
+	dma_buf_map_set_vaddr(map, cma_obj->vaddr);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(drm_gem_cma_vmap_local);
+
 /**
  * drm_gem_cma_mmap - memory-map an exported CMA GEM object
  * @obj: GEM object
diff --git a/drivers/gpu/drm/vc4/vc4_bo.c b/drivers/gpu/drm/vc4/vc4_bo.c
index dc316cb79e00..7283c018dbaf 100644
--- a/drivers/gpu/drm/vc4/vc4_bo.c
+++ b/drivers/gpu/drm/vc4/vc4_bo.c
@@ -387,6 +387,7 @@ static const struct drm_gem_object_funcs vc4_gem_object_funcs = {
 	.export = vc4_prime_export,
 	.get_sg_table = drm_gem_cma_get_sg_table,
 	.vmap = vc4_prime_vmap,
+	.vmap_local = drm_gem_cma_vmap_local,
 	.vm_ops = &vc4_vm_ops,
 };
 
diff --git a/include/drm/drm_gem_cma_helper.h b/include/drm/drm_gem_cma_helper.h
index 0a9711caa3e8..05122e71bc6d 100644
--- a/include/drm/drm_gem_cma_helper.h
+++ b/include/drm/drm_gem_cma_helper.h
@@ -99,6 +99,7 @@ drm_gem_cma_prime_import_sg_table(struct drm_device *dev,
 				  struct dma_buf_attachment *attach,
 				  struct sg_table *sgt);
 int drm_gem_cma_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_cma_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma);
 
 /**
-- 
2.29.2

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[PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:44:31 

Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
 include/drm/drm_gem_shmem_helper.h     |  2 +
 2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
 	.get_sg_table = drm_gem_shmem_get_sg_table,
 	.vmap = drm_gem_shmem_vmap,
 	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
 	.mmap = drm_gem_shmem_mmap,
 };
 
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
 }
 EXPORT_SYMBOL(drm_gem_shmem_unpin);
 
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
 {
 	struct drm_gem_object *obj = &shmem->base;
 	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
 	}
 
 	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
 		if (!ret) {
 			if (WARN_ON(map->is_iomem)) {
 				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
 	return ret;
 }
 
-/*
+/**
  * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
  * @shmem: shmem GEM object
  * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 	ret = mutex_lock_interruptible(&shmem->vmap_lock);
 	if (ret)
 		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
 	mutex_unlock(&shmem->vmap_lock);
 
 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_shmem_vmap);
 
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
 {
 	struct drm_gem_object *obj = &shmem->base;
 
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 		return;
 
 	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
 	else
 		vunmap(shmem->vaddr);
 
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 	drm_gem_shmem_put_pages(shmem);
 }
 
-/*
+/**
  * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
  * @shmem: shmem GEM object
  * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 
 	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
 	mutex_unlock(&shmem->vmap_lock);
 }
 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
 
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
 struct drm_gem_shmem_object *
 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
 int drm_gem_shmem_pin(struct drm_gem_object *obj);
 void drm_gem_shmem_unpin(struct drm_gem_object *obj);
 int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 
 int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
 
-- 
2.29.2

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[PATCH v4 06/13] drm/cirrus: Use drm_gem_shmem_vmap_local() in damage handling

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Damage handling in cirrus requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/cirrus.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index a043e602199e..21cd7056d45f 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -315,6 +315,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 			       struct drm_rect *rect)
 {
 	struct cirrus_device *cirrus = to_cirrus(fb->dev);
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int idx, ret;
@@ -323,9 +324,12 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	if (!drm_dev_enter(&cirrus->dev, &idx))
 		goto out;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (ret)
 		goto out_dev_exit;
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
+	if (ret)
+		goto out_dma_resv_unlock;
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	if (cirrus->cpp == fb->format->cpp[0])
@@ -345,9 +349,11 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	else
 		WARN_ON_ONCE("cpp mismatch");
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
 	ret = 0;
 
+	drm_gem_shmem_vunmap_local(obj, &map);
+out_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 out_dev_exit:
 	drm_dev_exit(idx);
 out:
-- 
2.29.2

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[PATCH v4 05/13] drm/mgag200: Use drm_gem_shmem_vmap_local() in damage handling

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Damage handling in mgag200 requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/mgag200/mgag200_mode.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 1dfc42170059..a33e28d4c5e9 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -1552,22 +1552,32 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
 		      struct drm_rect *clip)
 {
 	struct drm_device *dev = &mdev->base;
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int ret;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (drm_WARN_ON(dev, ret))
-		return; /* BUG: SHMEM BO should always be vmapped */
+		return;
+	ret = drm_gem_shmem_vmap_local(obj, &map);
+	if (drm_WARN_ON(dev, ret))
+		goto err_dma_resv_unlock; /* BUG: SHMEM BO should always be vmapped */
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_shmem_vunmap_local(obj, &map);
+	dma_resv_unlock(obj->resv);
 
 	/* Always scanout image at VRAM offset 0 */
 	mgag200_set_startadd(mdev, (u32)0);
 	mgag200_set_offset(mdev, fb);
+
+	return;
+
+err_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 }
 
 static void
-- 
2.29.2

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[PATCH v4 08/13] drm/udl: Use drm_gem_shmem_vmap_local() in damage handling

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Damage handling in udl requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/udl/udl_modeset.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
index 9d34ec9d03f6..46b55b4d03c2 100644
--- a/drivers/gpu/drm/udl/udl_modeset.c
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -290,14 +290,18 @@ static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
 	else if ((clip.x2 > fb->width) || (clip.y2 > fb->height))
 		return -EINVAL;
 
+	ret = dma_resv_lock(fb->obj[0]->resv, NULL);
+	if (ret)
+		return ret;
+
 	if (import_attach) {
 		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
 					       DMA_FROM_DEVICE);
 		if (ret)
-			return ret;
+			goto out_dma_resv_unlock;
 	}
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
 	if (ret) {
 		DRM_ERROR("failed to vmap fb\n");
 		goto out_dma_buf_end_cpu_access;
@@ -307,7 +311,7 @@ static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
 	urb = udl_get_urb(dev);
 	if (!urb) {
 		ret = -ENOMEM;
-		goto out_drm_gem_shmem_vunmap;
+		goto out_drm_gem_shmem_vunmap_local;
 	}
 	cmd = urb->transfer_buffer;
 
@@ -320,7 +324,7 @@ static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
 				       &cmd, byte_offset, dev_byte_offset,
 				       byte_width);
 		if (ret)
-			goto out_drm_gem_shmem_vunmap;
+			goto out_drm_gem_shmem_vunmap_local;
 	}
 
 	if (cmd > (char *)urb->transfer_buffer) {
@@ -336,8 +340,8 @@ static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
 
 	ret = 0;
 
-out_drm_gem_shmem_vunmap:
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+out_drm_gem_shmem_vunmap_local:
+	drm_gem_shmem_vunmap_local(fb->obj[0], &map);
 out_dma_buf_end_cpu_access:
 	if (import_attach) {
 		tmp_ret = dma_buf_end_cpu_access(import_attach->dmabuf,
@@ -345,6 +349,8 @@ static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
 		if (tmp_ret && !ret)
 			ret = tmp_ret; /* only update ret if not set yet */
 	}
+out_dma_resv_unlock:
+	dma_resv_unlock(fb->obj[0]->resv);
 
 	return ret;
 }
-- 
2.29.2

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[PATCH v4 13/13] drm/vram-helper: Remove unused drm_gem_vram_{vmap,vunmap}()

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

VRAM-helper BO's cannot be exported, so calls for vmap and vunmap
can only come from the BO's drivers or a kernel client. These are
supposed use vmap_local functionality.

The vmap and vunmap operations in VRAM helpers are therefore unused
and can be removed.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 98 ---------------------------
 include/drm/drm_gem_vram_helper.h     |  2 -
 2 files changed, 100 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index c7fba3a0758e..c7d166cd16df 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -379,72 +379,6 @@ int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
 }
 EXPORT_SYMBOL(drm_gem_vram_unpin);
 
-/**
- * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
- *                       space
- * @gbo: The GEM VRAM object to map
- * @map: Returns the kernel virtual address of the VRAM GEM object's backing
- *       store.
- *
- * The vmap function pins a GEM VRAM object to its current location, either
- * system or video memory, and maps its buffer into kernel address space.
- * As pinned object cannot be relocated, you should avoid pinning objects
- * permanently. Call drm_gem_vram_vunmap() with the returned address to
- * unmap and unpin the GEM VRAM object.
- *
- * Returns:
- * 0 on success, or a negative error code otherwise.
- */
-int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
-{
-	int ret;
-
-	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
-	if (ret)
-		return ret;
-
-	ret = drm_gem_vram_pin_locked(gbo, 0);
-	if (ret)
-		goto err_ttm_bo_unreserve;
-	ret = drm_gem_vram_vmap_local(gbo, map);
-	if (ret)
-		goto err_drm_gem_vram_unpin_locked;
-
-	ttm_bo_unreserve(&gbo->bo);
-
-	return 0;
-
-err_drm_gem_vram_unpin_locked:
-	drm_gem_vram_unpin_locked(gbo);
-err_ttm_bo_unreserve:
-	ttm_bo_unreserve(&gbo->bo);
-	return ret;
-}
-EXPORT_SYMBOL(drm_gem_vram_vmap);
-
-/**
- * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
- * @gbo: The GEM VRAM object to unmap
- * @map: Kernel virtual address where the VRAM GEM object was mapped
- *
- * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
- * the documentation for drm_gem_vram_vmap() for more information.
- */
-void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
-{
-	int ret;
-
-	ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);
-	if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
-		return;
-
-	drm_gem_vram_vunmap_local(gbo, map);
-	drm_gem_vram_unpin_locked(gbo);
-
-	ttm_bo_unreserve(&gbo->bo);
-}
-EXPORT_SYMBOL(drm_gem_vram_vunmap);
-
 /**
  * drm_gem_vram_vmap_local() - Maps a GEM VRAM object into kernel address space
  * @gbo: The GEM VRAM object to map
@@ -870,36 +804,6 @@ static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)
 	drm_gem_vram_unpin(gbo);
 }
 
-/**
- * drm_gem_vram_object_vmap() -
- *	Implements &struct drm_gem_object_funcs.vmap
- * @gem: The GEM object to map
- * @map: Returns the kernel virtual address of the VRAM GEM object's backing
- *       store.
- *
- * Returns:
- * 0 on success, or a negative error code otherwise.
- */
-static int drm_gem_vram_object_vmap(struct drm_gem_object *gem, struct dma_buf_map *map)
-{
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-
-	return drm_gem_vram_vmap(gbo, map);
-}
-
-/**
- * drm_gem_vram_object_vunmap() -
- *	Implements &struct drm_gem_object_funcs.vunmap
- * @gem: The GEM object to unmap
- * @map: Kernel virtual address where the VRAM GEM object was mapped
- */
-static void drm_gem_vram_object_vunmap(struct drm_gem_object *gem, struct dma_buf_map *map)
-{
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-
-	drm_gem_vram_vunmap(gbo, map);
-}
-
 static int drm_gem_vram_object_vmap_local(struct drm_gem_object *gem, struct dma_buf_map *map)
 {
 	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
@@ -922,8 +826,6 @@ static const struct drm_gem_object_funcs drm_gem_vram_object_funcs = {
 	.free = drm_gem_vram_object_free,
 	.pin = drm_gem_vram_object_pin,
 	.unpin = drm_gem_vram_object_unpin,
-	.vmap = drm_gem_vram_object_vmap,
-	.vunmap	= drm_gem_vram_object_vunmap,
 	.vmap_local = drm_gem_vram_object_vmap_local,
 	.vunmap_local = drm_gem_vram_object_vunmap_local,
 	.mmap = drm_gem_ttm_mmap,
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index bd6a60e7c22b..e571867f4069 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -97,8 +97,6 @@ u64 drm_gem_vram_mmap_offset(struct drm_gem_vram_object *gbo);
 s64 drm_gem_vram_offset(struct drm_gem_vram_object *gbo);
 int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag);
 int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo);
-int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
-void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 int drm_gem_vram_vmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 void drm_gem_vram_vunmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 
-- 
2.29.2

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[PATCH v4 10/13] drm/ast: Use drm_gem_vram_vmap_local() in cursor update

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Cursor updates in ast require a short-term mapping of the source and
destination BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/ast/ast_cursor.c | 37 +++++++++++++++++++++++---------
 1 file changed, 27 insertions(+), 10 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_cursor.c b/drivers/gpu/drm/ast/ast_cursor.c
index fac1ee79c372..c38f435bcde2 100644
--- a/drivers/gpu/drm/ast/ast_cursor.c
+++ b/drivers/gpu/drm/ast/ast_cursor.c
@@ -159,6 +159,8 @@ int ast_cursor_blit(struct ast_private *ast, struct drm_framebuffer *fb)
 	struct drm_device *dev = &ast->base;
 	struct drm_gem_vram_object *dst_gbo = ast->cursor.gbo[ast->cursor.next_index];
 	struct drm_gem_vram_object *src_gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *objs[] = {&src_gbo->bo.base, &dst_gbo->bo.base};
+	struct ww_acquire_ctx ctx;
 	struct dma_buf_map src_map, dst_map;
 	void __iomem *dst;
 	void *src;
@@ -168,26 +170,34 @@ int ast_cursor_blit(struct ast_private *ast, struct drm_framebuffer *fb)
 	    drm_WARN_ON_ONCE(dev, fb->height > AST_MAX_HWC_HEIGHT))
 		return -EINVAL;
 
-	ret = drm_gem_vram_vmap(src_gbo, &src_map);
+	ret = drm_gem_lock_reservations(objs, ARRAY_SIZE(objs), &ctx);
 	if (ret)
 		return ret;
+
+	ret = drm_gem_vram_vmap_local(src_gbo, &src_map);
+	if (ret)
+		goto err_drm_gem_unlock_reservations;
 	src = src_map.vaddr; /* TODO: Use mapping abstraction properly */
 
-	ret = drm_gem_vram_vmap(dst_gbo, &dst_map);
+	ret = drm_gem_vram_vmap_local(dst_gbo, &dst_map);
 	if (ret)
-		goto err_drm_gem_vram_vunmap;
+		goto err_drm_gem_vram_vunmap_local;
 	dst = dst_map.vaddr_iomem; /* TODO: Use mapping abstraction properly */
 
 	/* do data transfer to cursor BO */
 	update_cursor_image(dst, src, fb->width, fb->height);
 
-	drm_gem_vram_vunmap(dst_gbo, &dst_map);
-	drm_gem_vram_vunmap(src_gbo, &src_map);
+	drm_gem_vram_vunmap_local(dst_gbo, &dst_map);
+	drm_gem_vram_vunmap_local(src_gbo, &src_map);
+
+	drm_gem_unlock_reservations(objs, ARRAY_SIZE(objs), &ctx);
 
 	return 0;
 
-err_drm_gem_vram_vunmap:
-	drm_gem_vram_vunmap(src_gbo, &src_map);
+err_drm_gem_vram_vunmap_local:
+	drm_gem_vram_vunmap_local(src_gbo, &src_map);
+err_drm_gem_unlock_reservations:
+	drm_gem_unlock_reservations(objs, ARRAY_SIZE(objs), &ctx);
 	return ret;
 }
 
@@ -241,6 +251,7 @@ void ast_cursor_show(struct ast_private *ast, int x, int y,
 {
 	struct drm_device *dev = &ast->base;
 	struct drm_gem_vram_object *gbo = ast->cursor.gbo[ast->cursor.next_index];
+	struct drm_gem_object *obj = &gbo->bo.base;
 	struct dma_buf_map map;
 	u8 x_offset, y_offset;
 	u8 __iomem *dst;
@@ -248,16 +259,22 @@ void ast_cursor_show(struct ast_private *ast, int x, int y,
 	u8 jreg;
 	int ret;
 
-	ret = drm_gem_vram_vmap(gbo, &map);
-	if (drm_WARN_ONCE(dev, ret, "drm_gem_vram_vmap() failed, ret=%d\n", ret))
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
+	if (drm_WARN_ONCE(dev, ret, "drm_gem_vram_vmap_local() failed, ret=%d\n", ret)) {
+		dma_resv_unlock(obj->resv);
 		return;
+	}
 	dst = map.vaddr_iomem; /* TODO: Use mapping abstraction properly */
 
 	sig = dst + AST_HWC_SIZE;
 	writel(x, sig + AST_HWC_SIGNATURE_X);
 	writel(y, sig + AST_HWC_SIGNATURE_Y);
 
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
 
 	if (x < 0) {
 		x_offset = (-x) + offset_x;
-- 
2.29.2

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[PATCH v4 09/13] drm/vram-helper: Provide a vmap function for short-term mappings

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
It's somewhat inconvenient to callers that simply require a mapping of
the contained memory; and also ipmplies a certain overhead.

Therefore provide drm_gem_vram_vmap_local() drm_gem_vram_vunmap_local(),
which only perform the vmap/vunmap operations. Callers have to hold the
reservation lock while the mapping persists; or have to pin the BO by
themselves.

This patch connects GEM VRAM helpers to GEM object functions with
equivalent functionality.

v4:
	* move driver changes into separate patches (Daniel)
	* update documentation (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 141 +++++++++++++++++---------
 include/drm/drm_gem_vram_helper.h     |   2 +
 2 files changed, 95 insertions(+), 48 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index 02ca22e90290..c7fba3a0758e 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -379,47 +379,6 @@ int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
 }
 EXPORT_SYMBOL(drm_gem_vram_unpin);
 
-static int drm_gem_vram_kmap_locked(struct drm_gem_vram_object *gbo,
-				    struct dma_buf_map *map)
-{
-	int ret;
-
-	if (gbo->vmap_use_count > 0)
-		goto out;
-
-	ret = ttm_bo_vmap(&gbo->bo, &gbo->map);
-	if (ret)
-		return ret;
-
-out:
-	++gbo->vmap_use_count;
-	*map = gbo->map;
-
-	return 0;
-}
-
-static void drm_gem_vram_kunmap_locked(struct drm_gem_vram_object *gbo,
-				       struct dma_buf_map *map)
-{
-	struct drm_device *dev = gbo->bo.base.dev;
-
-	if (drm_WARN_ON_ONCE(dev, !gbo->vmap_use_count))
-		return;
-
-	if (drm_WARN_ON_ONCE(dev, !dma_buf_map_is_equal(&gbo->map, map)))
-		return; /* BUG: map not mapped from this BO */
-
-	if (--gbo->vmap_use_count > 0)
-		return;
-
-	/*
-	 * Permanently mapping and unmapping buffers adds overhead from
-	 * updating the page tables and creates debugging output. Therefore,
-	 * we delay the actual unmap operation until the BO gets evicted
-	 * from memory. See drm_gem_vram_bo_driver_move_notify().
-	 */
-}
-
 /**
  * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
  *                       space
@@ -447,7 +406,7 @@ int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
 	ret = drm_gem_vram_pin_locked(gbo, 0);
 	if (ret)
 		goto err_ttm_bo_unreserve;
-	ret = drm_gem_vram_kmap_locked(gbo, map);
+	ret = drm_gem_vram_vmap_local(gbo, map);
 	if (ret)
 		goto err_drm_gem_vram_unpin_locked;
 
@@ -479,13 +438,83 @@ void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *ma
 	if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
 		return;
 
-	drm_gem_vram_kunmap_locked(gbo, map);
+	drm_gem_vram_vunmap_local(gbo, map);
 	drm_gem_vram_unpin_locked(gbo);
 
 	ttm_bo_unreserve(&gbo->bo);
 }
 EXPORT_SYMBOL(drm_gem_vram_vunmap);
 
+/**
+ * drm_gem_vram_vmap_local() - Maps a GEM VRAM object into kernel address space
+ * @gbo: The GEM VRAM object to map
+ * @map: Returns the kernel virtual address of the VRAM GEM object's backing
+ *       store.
+ *
+ * The vmap_local function maps the buffer of a GEM VRAM object into kernel address
+ * space. Call drm_gem_vram_vunmap_local() with the returned address to unmap and
+ * unpin the GEM VRAM object.
+ *
+ * The function is called with the BO's reservation object locked. For short-term
+ * mappings, callers must hold the BO's reservation lock until after unmapping the
+ * buffer.
+ *
+ * Returns:
+ * 0 on success, or a negative error code otherwise.
+ */
+int drm_gem_vram_vmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
+{
+	int ret;
+
+	dma_resv_assert_held(gbo->bo.base.resv);
+
+	if (gbo->vmap_use_count > 0)
+		goto out;
+
+	ret = ttm_bo_vmap(&gbo->bo, &gbo->map);
+	if (ret)
+		return ret;
+
+out:
+	++gbo->vmap_use_count;
+	*map = gbo->map;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_gem_vram_vmap_local);
+
+/**
+ * drm_gem_vram_vunmap_local() - Unmaps a GEM VRAM object
+ * @gbo: The GEM VRAM object to unmap
+ * @map: Kernel virtual address where the VRAM GEM object was mapped
+ *
+ * A call to drm_gem_vram_vunmap_local() unmaps a GEM VRAM object's buffer. See
+ * the documentation for drm_gem_vram_vmap_local() for more information.
+ */
+void drm_gem_vram_vunmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
+{
+	struct drm_device *dev = gbo->bo.base.dev;
+
+	dma_resv_assert_held(gbo->bo.base.resv);
+
+	if (drm_WARN_ON_ONCE(dev, !gbo->vmap_use_count))
+		return;
+
+	if (drm_WARN_ON_ONCE(dev, !dma_buf_map_is_equal(&gbo->map, map)))
+		return; /* BUG: map not mapped from this BO */
+
+	if (--gbo->vmap_use_count > 0)
+		return;
+
+	/*
+	 * Permanently mapping and unmapping buffers adds overhead from
+	 * updating the page tables and creates debugging output. Therefore,
+	 * we delay the actual unmap operation until the BO gets evicted
+	 * from memory. See drm_gem_vram_bo_driver_move_notify().
+	 */
+}
+EXPORT_SYMBOL(drm_gem_vram_vunmap_local);
+
 /**
  * drm_gem_vram_fill_create_dumb() - \
 	Helper for implementing &struct drm_driver.dumb_create
@@ -871,17 +900,33 @@ static void drm_gem_vram_object_vunmap(struct drm_gem_object *gem, struct dma_bu
 	drm_gem_vram_vunmap(gbo, map);
 }
 
+static int drm_gem_vram_object_vmap_local(struct drm_gem_object *gem, struct dma_buf_map *map)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	return drm_gem_vram_vmap_local(gbo, map);
+}
+
+static void drm_gem_vram_object_vunmap_local(struct drm_gem_object *gem, struct dma_buf_map *map)
+{
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
+
+	drm_gem_vram_vunmap_local(gbo, map);
+}
+
 /*
  * GEM object funcs
  */
 
 static const struct drm_gem_object_funcs drm_gem_vram_object_funcs = {
-	.free	= drm_gem_vram_object_free,
-	.pin	= drm_gem_vram_object_pin,
-	.unpin	= drm_gem_vram_object_unpin,
-	.vmap	= drm_gem_vram_object_vmap,
+	.free = drm_gem_vram_object_free,
+	.pin = drm_gem_vram_object_pin,
+	.unpin = drm_gem_vram_object_unpin,
+	.vmap = drm_gem_vram_object_vmap,
 	.vunmap	= drm_gem_vram_object_vunmap,
-	.mmap   = drm_gem_ttm_mmap,
+	.vmap_local = drm_gem_vram_object_vmap_local,
+	.vunmap_local = drm_gem_vram_object_vunmap_local,
+	.mmap = drm_gem_ttm_mmap,
 	.print_info = drm_gem_ttm_print_info,
 };
 
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index a4bac02249c2..bd6a60e7c22b 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -99,6 +99,8 @@ int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag);
 int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo);
 int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
+int drm_gem_vram_vmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
+void drm_gem_vram_vunmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 
 int drm_gem_vram_fill_create_dumb(struct drm_file *file,
 				  struct drm_device *dev,
-- 
2.29.2

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[PATCH v4 12/13] drm/fb-helper: Move BO locking from DRM client to fbdev damage worker

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:26 

Fbdev emulation has to lock the BO into place while flushing the shadow
buffer into the BO's memory. Remove any interference with pinning by
using vmap_local functionality (instead of full vmap). This requires
BO reservation locking in fbdev's damage worker.

The new DRM client functions for locking and vmap_local functionality
are added for consistency with the existing style.

v4:
	* update documentation (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
---
 drivers/gpu/drm/drm_client.c    | 94 +++++++++++++++++++++++++++++++++
 drivers/gpu/drm/drm_fb_helper.c | 41 +++++++-------
 include/drm/drm_client.h        |  4 ++
 3 files changed, 119 insertions(+), 20 deletions(-)

diff --git a/drivers/gpu/drm/drm_client.c b/drivers/gpu/drm/drm_client.c
index ce45e380f4a2..0220165810aa 100644
--- a/drivers/gpu/drm/drm_client.c
+++ b/drivers/gpu/drm/drm_client.c
@@ -288,6 +288,37 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
 	return ERR_PTR(ret);
 }
 
+/**
+ * drm_client_buffer_lock - Locks the DRM client buffer
+ * @buffer: DRM client buffer
+ *
+ * This function locks the client buffer by acquiring the buffer
+ * object's reservation lock.
+ *
+ * Unlock the buffer with drm_client_buffer_unlock().
+ *
+ * Returns:
+ *	0 on success, or a negative errno code otherwise.
+ */
+int
+drm_client_buffer_lock(struct drm_client_buffer *buffer)
+{
+	return dma_resv_lock(buffer->gem->resv, NULL);
+}
+EXPORT_SYMBOL(drm_client_buffer_lock);
+
+/**
+ * drm_client_buffer_unlock - Unlock DRM client buffer
+ * @buffer: DRM client buffer
+ *
+ * Unlocks a client buffer. See drm_client_buffer_lock().
+ */
+void drm_client_buffer_unlock(struct drm_client_buffer *buffer)
+{
+	dma_resv_unlock(buffer->gem->resv);
+}
+EXPORT_SYMBOL(drm_client_buffer_unlock);
+
 /**
  * drm_client_buffer_vmap - Map DRM client buffer into address space
  * @buffer: DRM client buffer
@@ -305,6 +336,9 @@ drm_client_buffer_create(struct drm_client_dev *client, u32 width, u32 height, u
  * other vmap interfaces, you don't need it for the client's vunmap
  * function. So you can modify it at will during blit and draw operations.
  *
+ * drm_client_buffer_vmap() is for permanent or long-term mappings. See
+ * drm_client_buffer_vmap_local() for short-term mappings.
+ *
  * Returns:
  *	0 on success, or a negative errno code otherwise.
  */
@@ -348,6 +382,66 @@ void drm_client_buffer_vunmap(struct drm_client_buffer *buffer)
 }
 EXPORT_SYMBOL(drm_client_buffer_vunmap);
 
+/**
+ * drm_client_buffer_vmap_local - Map DRM client buffer into address space
+ * @buffer: DRM client buffer
+ * @map_copy: Returns the mapped memory's address
+ *
+ * This function maps a client buffer into kernel address space. If the
+ * buffer is already mapped, it returns the existing mapping's address.
+ *
+ * Client buffer mappings are not ref'counted. Each call to
+ * drm_client_buffer_vmap_local() should be followed by a call to
+ * drm_client_buffer_vunmap_local(); or the client buffer should be mapped
+ * throughout its lifetime.
+ *
+ * The returned address is a copy of the internal value. In contrast to
+ * other vmap interfaces, you don't need it for the client's vunmap
+ * function. So you can modify it at will during blit and draw operations.
+ *
+ * Returns:
+ *	0 on success, or a negative errno code otherwise.
+ */
+int
+drm_client_buffer_vmap_local(struct drm_client_buffer *buffer, struct dma_buf_map *map_copy)
+{
+	struct dma_buf_map *map = &buffer->map;
+	int ret;
+
+	/*
+	 * FIXME: The dependency on GEM here isn't required, we could
+	 * convert the driver handle to a dma-buf instead and use the
+	 * backend-agnostic dma-buf vmap_local support instead. This would
+	 * require that the handle2fd prime ioctl is reworked to pull the
+	 * fd_install step out of the driver backend hooks, to make that
+	 * final step optional for internal users.
+	 */
+	ret = drm_gem_vmap_local(buffer->gem, map);
+	if (ret)
+		return ret;
+
+	*map_copy = *map;
+
+	return 0;
+}
+EXPORT_SYMBOL(drm_client_buffer_vmap_local);
+
+/**
+ * drm_client_buffer_vunmap_local - Unmap DRM client buffer
+ * @buffer: DRM client buffer
+ *
+ * This function removes a client buffer's memory mapping. Calling this
+ * function is only required by clients that manage their buffer mappings
+ * by themselves.
+ */
+void drm_client_buffer_vunmap_local(struct drm_client_buffer *buffer)
+{
+	struct dma_buf_map *map = &buffer->map;
+
+	drm_gem_vunmap_local(buffer->gem, map);
+}
+EXPORT_SYMBOL(drm_client_buffer_vunmap_local);
+
 static void drm_client_buffer_rmfb(struct drm_client_buffer *buffer)
 {
 	int ret;
diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index a44c3a438059..283d27f8fe67 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -399,28 +399,34 @@ static int drm_fb_helper_damage_blit(struct drm_fb_helper *fb_helper,
 	int ret;
 
 	/*
-	 * We have to pin the client buffer to its current location while
-	 * flushing the shadow buffer. In the general case, concurrent
-	 * modesetting operations could try to move the buffer and would
-	 * fail. The modeset has to be serialized by acquiring the reservation
-	 * object of the underlying BO here.
-	 *
 	 * For fbdev emulation, we only have to protect against fbdev modeset
 	 * operations. Nothing else will involve the client buffer's BO. So it
 	 * is sufficient to acquire struct drm_fb_helper.lock here.
 	 */
 	mutex_lock(&fb_helper->lock);
 
-	ret = drm_client_buffer_vmap(buffer, &map);
+	/*
+	 * We have to keep the client buffer at its current location while
+	 * flushing the shadow buffer. Concurrent operations could otherwise
+	 * try to move the buffer. Therefore acquiring the reservation
+	 * object of the underlying BO here.
+	 */
+	ret = drm_client_buffer_lock(buffer);
+	if (ret)
+		goto out_mutex_unlock;
+
+	ret = drm_client_buffer_vmap_local(buffer, &map);
 	if (ret)
-		goto out;
+		goto out_drm_client_buffer_unlock;
 
 	dst = map;
 	drm_fb_helper_damage_blit_real(fb_helper, clip, &dst);
 
-	drm_client_buffer_vunmap(buffer);
+	drm_client_buffer_vunmap_local(buffer);
 
-out:
+out_drm_client_buffer_unlock:
+	drm_client_buffer_unlock(buffer);
+out_mutex_unlock:
 	mutex_unlock(&fb_helper->lock);
 
 	return ret;
@@ -946,15 +952,11 @@ static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 	drm_modeset_lock_all(fb_helper->dev);
 	drm_client_for_each_modeset(modeset, &fb_helper->client) {
 		crtc = modeset->crtc;
-		if (!crtc->funcs->gamma_set || !crtc->gamma_size) {
-			ret = -EINVAL;
-			goto out;
-		}
+		if (!crtc->funcs->gamma_set || !crtc->gamma_size)
+			return -EINVAL;
 
-		if (cmap->start + cmap->len > crtc->gamma_size) {
-			ret = -EINVAL;
-			goto out;
-		}
+		if (cmap->start + cmap->len > crtc->gamma_size)
+			return -EINVAL;
 
 		r = crtc->gamma_store;
 		g = r + crtc->gamma_size;
@@ -967,9 +969,8 @@ static int setcmap_legacy(struct fb_cmap *cmap, struct fb_info *info)
 		ret = crtc->funcs->gamma_set(crtc, r, g, b,
 					     crtc->gamma_size, NULL);
 		if (ret)
-			goto out;
+			return ret;
 	}
-out:
 	drm_modeset_unlock_all(fb_helper->dev);
 
 	return ret;
diff --git a/include/drm/drm_client.h b/include/drm/drm_client.h
index f07f2fb02e75..df61e339a11c 100644
--- a/include/drm/drm_client.h
+++ b/include/drm/drm_client.h
@@ -156,8 +156,12 @@ struct drm_client_buffer *
 drm_client_framebuffer_create(struct drm_client_dev *client, u32 width, u32 height, u32 format);
 void drm_client_framebuffer_delete(struct drm_client_buffer *buffer);
 int drm_client_framebuffer_flush(struct drm_client_buffer *buffer, struct drm_rect *rect);
+int drm_client_buffer_lock(struct drm_client_buffer *buffer);
+void drm_client_buffer_unlock(struct drm_client_buffer *buffer);
 int drm_client_buffer_vmap(struct drm_client_buffer *buffer, struct dma_buf_map *map);
 void drm_client_buffer_vunmap(struct drm_client_buffer *buffer);
+int drm_client_buffer_vmap_local(struct drm_client_buffer *buffer, struct dma_buf_map *map);
+void drm_client_buffer_vunmap_local(struct drm_client_buffer *buffer);
 
 int drm_client_modeset_create(struct drm_client_dev *client);
 void drm_client_modeset_free(struct drm_client_dev *client);
-- 
2.29.2

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[PATCH v4 11/13] drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:27 

Cursor updates in vboxvideo require a short-term mapping of the
source BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/vboxvideo/vbox_mode.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
index dbc0dd53c69e..215b37c78c10 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
@@ -381,7 +381,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 		container_of(plane->dev, struct vbox_private, ddev);
 	struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
 	struct drm_framebuffer *fb = plane->state->fb;
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *obj = fb->obj[0];
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(obj);
 	u32 width = plane->state->crtc_w;
 	u32 height = plane->state->crtc_h;
 	size_t data_size, mask_size;
@@ -401,11 +402,12 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 
 	vbox_crtc->cursor_enabled = true;
 
-	ret = drm_gem_vram_vmap(gbo, &map);
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
 	if (ret) {
-		/*
-		 * BUG: we should have pinned the BO in prepare_fb().
-		 */
+		dma_resv_unlock(obj->resv);
 		mutex_unlock(&vbox->hw_mutex);
 		DRM_WARN("Could not map cursor bo, skipping update\n");
 		return;
@@ -421,7 +423,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 	data_size = width * height * 4 + mask_size;
 
 	copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
 
 	flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
 		VBOX_MOUSE_POINTER_ALPHA;
-- 
2.29.2

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[PATCH v4 07/13] drm/gm12u320: Use drm_gem_shmem_vmap_local() in damage handling

From: Thomas Zimmermann <tzimmermann@suse.de>
Date: 2021-01-08 09:45:29 

Damage handling in gm12u320 requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/gm12u320.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tiny/gm12u320.c b/drivers/gpu/drm/tiny/gm12u320.c
index 33f65f4626e5..b0c6e350f2b3 100644
--- a/drivers/gpu/drm/tiny/gm12u320.c
+++ b/drivers/gpu/drm/tiny/gm12u320.c
@@ -265,11 +265,16 @@ static void gm12u320_copy_fb_to_blocks(struct gm12u320_device *gm12u320)
 	y1 = gm12u320->fb_update.rect.y1;
 	y2 = gm12u320->fb_update.rect.y2;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(fb->obj[0]->resv, NULL);
 	if (ret) {
-		GM12U320_ERR("failed to vmap fb: %d\n", ret);
+		GM12U320_ERR("failed to reserve fb: %d\n", ret);
 		goto put_fb;
 	}
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
+	if (ret) {
+		GM12U320_ERR("failed to vmap fb: %d\n", ret);
+		goto unlock_resv;
+	}
 	vaddr = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	if (fb->obj[0]->import_attach) {
@@ -321,8 +326,11 @@ static void gm12u320_copy_fb_to_blocks(struct gm12u320_device *gm12u320)
 		if (ret)
 			GM12U320_ERR("dma_buf_end_cpu_access err: %d\n", ret);
 	}
+
+unlock_resv:
+	dma_resv_unlock(fb->obj[0]->resv);
 vunmap:
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_shmem_vunmap_local(fb->obj[0], &map);
 put_fb:
 	drm_framebuffer_put(fb);
 	gm12u320->fb_update.fb = NULL;
-- 
2.29.2

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Re: [PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

From: Daniel Vetter <hidden>
Date: 2021-01-11 16:51:32 

On Fri, Jan 08, 2021 at 10:43:31AM +0100, Thomas Zimmermann wrote:
quoted hunk
Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
 include/drm/drm_gem_shmem_helper.h     |  2 +
 2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
 	.get_sg_table = drm_gem_shmem_get_sg_table,
 	.vmap = drm_gem_shmem_vmap,
 	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
 	.mmap = drm_gem_shmem_mmap,
 };
 
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
 }
 EXPORT_SYMBOL(drm_gem_shmem_unpin);
 
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
This is a bit spaghetti and also has the problem that we're not changing
shmem->vmap_use_count under different locks, depending upon which path
we're taking.

I think the cleanest would be if we pull the if (import_attach) case out
of the _locked() version completely, for all cases, and also outside of
the shmem->vmap_lock. This means no caching of vmaps in the shmem layer
anymore for imported buffers, but this is no longer a problem: We cache
them in the exporters instead (I think at least, if not maybe need to fix
that where it's expensive).

Other option would be to unly pull it out for the _vmap_local case, but
that's a bit ugly because no longer symmetrical in the various paths.
quoted hunk
 {
 	struct drm_gem_object *obj = &shmem->base;
 	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
 	}
 
 	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
 		if (!ret) {
 			if (WARN_ON(map->is_iomem)) {
 				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
 	return ret;
 }
 
-/*
+/**
  * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
  * @shmem: shmem GEM object
  * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 	ret = mutex_lock_interruptible(&shmem->vmap_lock);
 	if (ret)
 		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
 	mutex_unlock(&shmem->vmap_lock);
 
 	return ret;
 }
 EXPORT_SYMBOL(drm_gem_shmem_vmap);
 
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
So for the other callbacks I tried to make sure we have different entry
points for this, since it's not really the same thing and because of the
locking mess we have with dma_resv_lock vs various pre-existing local
locking scheme, it's easy to get a mess.

I think the super clean version here would be to also export just the
internal stuff for the ->v(un)map_local hooks, but that's maybe a bit too
much boilerplate for no real gain.
-Daniel
quoted hunk
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
 static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
 {
 	struct drm_gem_object *obj = &shmem->base;
 
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 		return;
 
 	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
 	else
 		vunmap(shmem->vaddr);
 
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
 	drm_gem_shmem_put_pages(shmem);
 }
 
-/*
+/**
  * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
  * @shmem: shmem GEM object
  * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
 	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
 
 	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
 	mutex_unlock(&shmem->vmap_lock);
 }
 EXPORT_SYMBOL(drm_gem_shmem_vunmap);
 
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
 struct drm_gem_shmem_object *
 drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
 				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
 int drm_gem_shmem_pin(struct drm_gem_object *obj);
 void drm_gem_shmem_unpin(struct drm_gem_object *obj);
 int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
 
 int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
 
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v4 13/13] drm/vram-helper: Remove unused drm_gem_vram_{vmap,vunmap}()

From: Daniel Vetter <hidden>
Date: 2021-01-11 16:53:18 

On Fri, Jan 08, 2021 at 10:43:40AM +0100, Thomas Zimmermann wrote:
VRAM-helper BO's cannot be exported, so calls for vmap and vunmap
can only come from the BO's drivers or a kernel client. These are
supposed use vmap_local functionality.
	  ^to

The vmap and vunmap operations in VRAM helpers are therefore unused
and can be removed.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
quoted hunk
---
 drivers/gpu/drm/drm_gem_vram_helper.c | 98 ---------------------------
 include/drm/drm_gem_vram_helper.h     |  2 -
 2 files changed, 100 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_vram_helper.c b/drivers/gpu/drm/drm_gem_vram_helper.c
index c7fba3a0758e..c7d166cd16df 100644
--- a/drivers/gpu/drm/drm_gem_vram_helper.c
+++ b/drivers/gpu/drm/drm_gem_vram_helper.c
@@ -379,72 +379,6 @@ int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo)
 }
 EXPORT_SYMBOL(drm_gem_vram_unpin);
 
-/**
- * drm_gem_vram_vmap() - Pins and maps a GEM VRAM object into kernel address
- *                       space
- * @gbo: The GEM VRAM object to map
- * @map: Returns the kernel virtual address of the VRAM GEM object's backing
- *       store.
- *
- * The vmap function pins a GEM VRAM object to its current location, either
- * system or video memory, and maps its buffer into kernel address space.
- * As pinned object cannot be relocated, you should avoid pinning objects
- * permanently. Call drm_gem_vram_vunmap() with the returned address to
- * unmap and unpin the GEM VRAM object.
- *
- * Returns:
- * 0 on success, or a negative error code otherwise.
- */
-int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
-{
-	int ret;
-
-	ret = ttm_bo_reserve(&gbo->bo, true, false, NULL);
-	if (ret)
-		return ret;
-
-	ret = drm_gem_vram_pin_locked(gbo, 0);
-	if (ret)
-		goto err_ttm_bo_unreserve;
-	ret = drm_gem_vram_vmap_local(gbo, map);
-	if (ret)
-		goto err_drm_gem_vram_unpin_locked;
-
-	ttm_bo_unreserve(&gbo->bo);
-
-	return 0;
-
-err_drm_gem_vram_unpin_locked:
-	drm_gem_vram_unpin_locked(gbo);
-err_ttm_bo_unreserve:
-	ttm_bo_unreserve(&gbo->bo);
-	return ret;
-}
-EXPORT_SYMBOL(drm_gem_vram_vmap);
-
-/**
- * drm_gem_vram_vunmap() - Unmaps and unpins a GEM VRAM object
- * @gbo: The GEM VRAM object to unmap
- * @map: Kernel virtual address where the VRAM GEM object was mapped
- *
- * A call to drm_gem_vram_vunmap() unmaps and unpins a GEM VRAM buffer. See
- * the documentation for drm_gem_vram_vmap() for more information.
- */
-void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map)
-{
-	int ret;
-
-	ret = ttm_bo_reserve(&gbo->bo, false, false, NULL);
-	if (WARN_ONCE(ret, "ttm_bo_reserve_failed(): ret=%d\n", ret))
-		return;
-
-	drm_gem_vram_vunmap_local(gbo, map);
-	drm_gem_vram_unpin_locked(gbo);
-
-	ttm_bo_unreserve(&gbo->bo);
-}
-EXPORT_SYMBOL(drm_gem_vram_vunmap);
-
 /**
  * drm_gem_vram_vmap_local() - Maps a GEM VRAM object into kernel address space
  * @gbo: The GEM VRAM object to map
@@ -870,36 +804,6 @@ static void drm_gem_vram_object_unpin(struct drm_gem_object *gem)
 	drm_gem_vram_unpin(gbo);
 }
 
-/**
- * drm_gem_vram_object_vmap() -
- *	Implements &struct drm_gem_object_funcs.vmap
- * @gem: The GEM object to map
- * @map: Returns the kernel virtual address of the VRAM GEM object's backing
- *       store.
- *
- * Returns:
- * 0 on success, or a negative error code otherwise.
- */
-static int drm_gem_vram_object_vmap(struct drm_gem_object *gem, struct dma_buf_map *map)
-{
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-
-	return drm_gem_vram_vmap(gbo, map);
-}
-
-/**
- * drm_gem_vram_object_vunmap() -
- *	Implements &struct drm_gem_object_funcs.vunmap
- * @gem: The GEM object to unmap
- * @map: Kernel virtual address where the VRAM GEM object was mapped
- */
-static void drm_gem_vram_object_vunmap(struct drm_gem_object *gem, struct dma_buf_map *map)
-{
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
-
-	drm_gem_vram_vunmap(gbo, map);
-}
-
 static int drm_gem_vram_object_vmap_local(struct drm_gem_object *gem, struct dma_buf_map *map)
 {
 	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(gem);
@@ -922,8 +826,6 @@ static const struct drm_gem_object_funcs drm_gem_vram_object_funcs = {
 	.free = drm_gem_vram_object_free,
 	.pin = drm_gem_vram_object_pin,
 	.unpin = drm_gem_vram_object_unpin,
-	.vmap = drm_gem_vram_object_vmap,
-	.vunmap	= drm_gem_vram_object_vunmap,
 	.vmap_local = drm_gem_vram_object_vmap_local,
 	.vunmap_local = drm_gem_vram_object_vunmap_local,
 	.mmap = drm_gem_ttm_mmap,
diff --git a/include/drm/drm_gem_vram_helper.h b/include/drm/drm_gem_vram_helper.h
index bd6a60e7c22b..e571867f4069 100644
--- a/include/drm/drm_gem_vram_helper.h
+++ b/include/drm/drm_gem_vram_helper.h
@@ -97,8 +97,6 @@ u64 drm_gem_vram_mmap_offset(struct drm_gem_vram_object *gbo);
 s64 drm_gem_vram_offset(struct drm_gem_vram_object *gbo);
 int drm_gem_vram_pin(struct drm_gem_vram_object *gbo, unsigned long pl_flag);
 int drm_gem_vram_unpin(struct drm_gem_vram_object *gbo);
-int drm_gem_vram_vmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
-void drm_gem_vram_vunmap(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 int drm_gem_vram_vmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 void drm_gem_vram_vunmap_local(struct drm_gem_vram_object *gbo, struct dma_buf_map *map);
 
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v4 05/13] drm/mgag200: Use drm_gem_shmem_vmap_local() in damage handling

From: Daniel Vetter <hidden>
Date: 2021-01-11 16:54:39 

On Fri, Jan 08, 2021 at 10:43:32AM +0100, Thomas Zimmermann wrote:
Damage handling in mgag200 requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
quoted hunk
---
 drivers/gpu/drm/mgag200/mgag200_mode.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 1dfc42170059..a33e28d4c5e9 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -1552,22 +1552,32 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
 		      struct drm_rect *clip)
 {
 	struct drm_device *dev = &mdev->base;
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int ret;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (drm_WARN_ON(dev, ret))
-		return; /* BUG: SHMEM BO should always be vmapped */
+		return;
+	ret = drm_gem_shmem_vmap_local(obj, &map);
+	if (drm_WARN_ON(dev, ret))
+		goto err_dma_resv_unlock; /* BUG: SHMEM BO should always be vmapped */
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_shmem_vunmap_local(obj, &map);
+	dma_resv_unlock(obj->resv);
 
 	/* Always scanout image at VRAM offset 0 */
 	mgag200_set_startadd(mdev, (u32)0);
 	mgag200_set_offset(mdev, fb);
+
+	return;
+
+err_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 }
 
 static void
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v4 05/13] drm/mgag200: Use drm_gem_shmem_vmap_local() in damage handling

From: Daniel Vetter <hidden>
Date: 2021-01-11 16:58:59 

On Mon, Jan 11, 2021 at 05:53:41PM +0100, Daniel Vetter wrote:
On Fri, Jan 08, 2021 at 10:43:32AM +0100, Thomas Zimmermann wrote:
quoted
Damage handling in mgag200 requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Daniel Vetter <redacted>
On second thought, strike that r-b, I have a confused question.
quoted
---
 drivers/gpu/drm/mgag200/mgag200_mode.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 1dfc42170059..a33e28d4c5e9 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -1552,22 +1552,32 @@ mgag200_handle_damage(struct mga_device *mdev, struct drm_framebuffer *fb,
 		      struct drm_rect *clip)
 {
 	struct drm_device *dev = &mdev->base;
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int ret;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (drm_WARN_ON(dev, ret))
-		return; /* BUG: SHMEM BO should always be vmapped */
+		return;
+	ret = drm_gem_shmem_vmap_local(obj, &map);
+	if (drm_WARN_ON(dev, ret))
+		goto err_dma_resv_unlock; /* BUG: SHMEM BO should always be vmapped */
Why is this guaranteed? I tried to hunt for a vmap in mga200g code, and
dind't find any. I'd ahve expected something in prepare/finish_fb.

Also since this is not a vram-helper using driver, why convert it over to
vmap_local? I guess that should also be explained in the commit message a
bit better.
-Daniel

quoted
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	drm_fb_memcpy_dstclip(mdev->vram, vmap, fb, clip);
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_shmem_vunmap_local(obj, &map);
+	dma_resv_unlock(obj->resv);
 
 	/* Always scanout image at VRAM offset 0 */
 	mgag200_set_startadd(mdev, (u32)0);
 	mgag200_set_offset(mdev, fb);
+
+	return;
+
+err_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 }
 
 static void
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
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Re: [PATCH v4 06/13] drm/cirrus: Use drm_gem_shmem_vmap_local() in damage handling

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-11 17:01:29 
    

  

  
On Fri, Jan 08, 2021 at 10:43:33AM +0100, Thomas Zimmermann wrote:
Damage handling in cirrus requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Hm more possible errors that we don't report to userspace ... Why don't we
vmap/vunmap these in prepare/cleanup_fb? Generally we'd want a long-term
vmap here to make sure this all works nicely.

Since it's nothing new, on this patch:

Reviewed-by: Daniel Vetter <redacted>

quoted hunk
---
 drivers/gpu/drm/tiny/cirrus.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index a043e602199e..21cd7056d45f 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -315,6 +315,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 			       struct drm_rect *rect)
 {
 	struct cirrus_device *cirrus = to_cirrus(fb->dev);
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int idx, ret;
@@ -323,9 +324,12 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	if (!drm_dev_enter(&cirrus->dev, &idx))
 		goto out;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (ret)
 		goto out_dev_exit;
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
+	if (ret)
+		goto out_dma_resv_unlock;
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	if (cirrus->cpp == fb->format->cpp[0])
@@ -345,9 +349,11 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	else
 		WARN_ON_ONCE("cpp mismatch");
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
 	ret = 0;
 
+	drm_gem_shmem_vunmap_local(obj, &map);
+out_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 out_dev_exit:
 	drm_dev_exit(idx);
 out:
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: [PATCH v4 07/13] drm/gm12u320: Use drm_gem_shmem_vmap_local() in damage handling

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-11 17:01:49 
    

  

  
On Fri, Jan 08, 2021 at 10:43:34AM +0100, Thomas Zimmermann wrote:
quoted hunk
Damage handling in gm12u320 requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
 drivers/gpu/drm/tiny/gm12u320.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/tiny/gm12u320.c b/drivers/gpu/drm/tiny/gm12u320.c
index 33f65f4626e5..b0c6e350f2b3 100644
--- a/drivers/gpu/drm/tiny/gm12u320.c
+++ b/drivers/gpu/drm/tiny/gm12u320.c
@@ -265,11 +265,16 @@ static void gm12u320_copy_fb_to_blocks(struct gm12u320_device *gm12u320)
 	y1 = gm12u320->fb_update.rect.y1;
 	y2 = gm12u320->fb_update.rect.y2;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(fb->obj[0]->resv, NULL);
 	if (ret) {
-		GM12U320_ERR("failed to vmap fb: %d\n", ret);
+		GM12U320_ERR("failed to reserve fb: %d\n", ret);
 		goto put_fb;
 	}
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
+	if (ret) {
+		GM12U320_ERR("failed to vmap fb: %d\n", ret);
+		goto unlock_resv;
+	}
 	vaddr = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	if (fb->obj[0]->import_attach) {
@@ -321,8 +326,11 @@ static void gm12u320_copy_fb_to_blocks(struct gm12u320_device *gm12u320)
 		if (ret)
 			GM12U320_ERR("dma_buf_end_cpu_access err: %d\n", ret);
 	}
+
+unlock_resv:
+	dma_resv_unlock(fb->obj[0]->resv);
Unlock before vunmap.
-Daniel

 vunmap:
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
+	drm_gem_shmem_vunmap_local(fb->obj[0], &map);
 put_fb:
 	drm_framebuffer_put(fb);
 	gm12u320->fb_update.fb = NULL;
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
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Re: [PATCH v4 06/13] drm/cirrus: Use drm_gem_shmem_vmap_local() in damage handling

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-11 17:04:23 
    

  

  
On Mon, Jan 11, 2021 at 06:00:42PM +0100, Daniel Vetter wrote:
On Fri, Jan 08, 2021 at 10:43:33AM +0100, Thomas Zimmermann wrote:
quoted
Damage handling in cirrus requires a short-term mapping of the source
BO. Use drm_gem_shmem_vmap_local().

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Hm more possible errors that we don't report to userspace ... Why don't we
vmap/vunmap these in prepare/cleanup_fb? Generally we'd want a long-term
vmap here to make sure this all works nicely.

Since it's nothing new, on this patch:

Reviewed-by: Daniel Vetter <redacted>
Ok, also strike this r-b here. This is called from that atomic commit
paths, and we cannot call dma_resv_lock here. This should splat with
lockdep enabled against the dma-fence annotations I've merged, I'm kinda
surprised it doesn't?
-Daniel

quoted
---
 drivers/gpu/drm/tiny/cirrus.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/tiny/cirrus.c b/drivers/gpu/drm/tiny/cirrus.c
index a043e602199e..21cd7056d45f 100644
--- a/drivers/gpu/drm/tiny/cirrus.c
+++ b/drivers/gpu/drm/tiny/cirrus.c
@@ -315,6 +315,7 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 			       struct drm_rect *rect)
 {
 	struct cirrus_device *cirrus = to_cirrus(fb->dev);
+	struct drm_gem_object *obj = fb->obj[0];
 	struct dma_buf_map map;
 	void *vmap;
 	int idx, ret;
@@ -323,9 +324,12 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	if (!drm_dev_enter(&cirrus->dev, &idx))
 		goto out;
 
-	ret = drm_gem_shmem_vmap(fb->obj[0], &map);
+	ret = dma_resv_lock(obj->resv, NULL);
 	if (ret)
 		goto out_dev_exit;
+	ret = drm_gem_shmem_vmap_local(fb->obj[0], &map);
+	if (ret)
+		goto out_dma_resv_unlock;
 	vmap = map.vaddr; /* TODO: Use mapping abstraction properly */
 
 	if (cirrus->cpp == fb->format->cpp[0])
@@ -345,9 +349,11 @@ static int cirrus_fb_blit_rect(struct drm_framebuffer *fb,
 	else
 		WARN_ON_ONCE("cpp mismatch");
 
-	drm_gem_shmem_vunmap(fb->obj[0], &map);
 	ret = 0;
 
+	drm_gem_shmem_vunmap_local(obj, &map);
+out_dma_resv_unlock:
+	dma_resv_unlock(obj->resv);
 out_dev_exit:
 	drm_dev_exit(idx);
 out:
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
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Re: [PATCH v4 11/13] drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-11 17:07:09 
    

  

  
On Fri, Jan 08, 2021 at 10:43:38AM +0100, Thomas Zimmermann wrote:
Cursor updates in vboxvideo require a short-term mapping of the
source BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
All these drivers patches break the dma_resv_lock vs
dma_fence_begin/end_signalling nesting rules, so this doesn't work.

Generally this is what the prepare/cleanup_fb hooks are for, that's where
mappings (including vmaps) are meant to be set up, permanently.

I'm kinda not clear on why we need all these changes, I thought the
locking problem is just in the fb helper paths, because it's outside of
the atomic path and could conflict with an atomic update at the same time?
So only that one should get the vmap_local treatment, everything else
should keep the normal vmap treatment.
-Daniel
quoted hunk
---
 drivers/gpu/drm/vboxvideo/vbox_mode.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
index dbc0dd53c69e..215b37c78c10 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
@@ -381,7 +381,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 		container_of(plane->dev, struct vbox_private, ddev);
 	struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
 	struct drm_framebuffer *fb = plane->state->fb;
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *obj = fb->obj[0];
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(obj);
 	u32 width = plane->state->crtc_w;
 	u32 height = plane->state->crtc_h;
 	size_t data_size, mask_size;
@@ -401,11 +402,12 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 
 	vbox_crtc->cursor_enabled = true;
 
-	ret = drm_gem_vram_vmap(gbo, &map);
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
 	if (ret) {
-		/*
-		 * BUG: we should have pinned the BO in prepare_fb().
-		 */
+		dma_resv_unlock(obj->resv);
 		mutex_unlock(&vbox->hw_mutex);
 		DRM_WARN("Could not map cursor bo, skipping update\n");
 		return;
@@ -421,7 +423,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
 	data_size = width * height * 4 + mask_size;
 
 	copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
 
 	flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
 		VBOX_MOUSE_POINTER_ALPHA;
-- 
2.29.2
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
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Re: [PATCH v4 11/13] drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update

    

      From: Thomas Zimmermann <tzimmermann@suse.de>

      Date: 2021-01-12 07:55:02 
    

  

  
Hi

Am 11.01.21 um 18:06 schrieb Daniel Vetter:
On Fri, Jan 08, 2021 at 10:43:38AM +0100, Thomas Zimmermann wrote:
quoted
Cursor updates in vboxvideo require a short-term mapping of the
source BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
All these drivers patches break the dma_resv_lock vs
dma_fence_begin/end_signalling nesting rules, so this doesn't work.

Generally this is what the prepare/cleanup_fb hooks are for, that's where
mappings (including vmaps) are meant to be set up, permanently.

I'm kinda not clear on why we need all these changes, I thought the
locking problem is just in the fb helper paths, because it's outside of
the atomic path and could conflict with an atomic update at the same time?
So only that one should get the vmap_local treatment, everything else
should keep the normal vmap treatment.
Kind of responding to all your comment on the driver changes:

These drivers only require short-term mappings, so using vmap_local 
would be the natural choice. For SHMEM helpers, it's mostly a cosmetic 
thing. For VRAM helpers, I was hoping to remove the vmap/vunmap helpers 
entirely. One cannot really map the BOs for the long-term, so not having 
the helpers at all would make sense.

But reading all your comments on the driver patches, I'd rather not 
update the drivers here but later convert them to use 
prepare_fb/cleanup_fb in the correct way.

Best regards
Thomas

-Daniel
quoted
---
  drivers/gpu/drm/vboxvideo/vbox_mode.c | 15 +++++++++------
  1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
index dbc0dd53c69e..215b37c78c10 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
@@ -381,7 +381,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  		container_of(plane->dev, struct vbox_private, ddev);
  	struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
  	struct drm_framebuffer *fb = plane->state->fb;
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *obj = fb->obj[0];
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(obj);
  	u32 width = plane->state->crtc_w;
  	u32 height = plane->state->crtc_h;
  	size_t data_size, mask_size;
@@ -401,11 +402,12 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  
  	vbox_crtc->cursor_enabled = true;
  
-	ret = drm_gem_vram_vmap(gbo, &map);
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
  	if (ret) {
-		/*
-		 * BUG: we should have pinned the BO in prepare_fb().
-		 */
+		dma_resv_unlock(obj->resv);
  		mutex_unlock(&vbox->hw_mutex);
  		DRM_WARN("Could not map cursor bo, skipping update\n");
  		return;
@@ -421,7 +423,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  	data_size = width * height * 4 + mask_size;
  
  	copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
  
  	flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
  		VBOX_MOUSE_POINTER_ALPHA;
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer






  

    
Re: [PATCH v4 11/13] drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-12 09:18:02 
    

  

  
On Tue, Jan 12, 2021 at 08:54:02AM +0100, Thomas Zimmermann wrote:
Hi

Am 11.01.21 um 18:06 schrieb Daniel Vetter:
quoted
On Fri, Jan 08, 2021 at 10:43:38AM +0100, Thomas Zimmermann wrote:
quoted
Cursor updates in vboxvideo require a short-term mapping of the
source BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
All these drivers patches break the dma_resv_lock vs
dma_fence_begin/end_signalling nesting rules, so this doesn't work.

Generally this is what the prepare/cleanup_fb hooks are for, that's where
mappings (including vmaps) are meant to be set up, permanently.

I'm kinda not clear on why we need all these changes, I thought the
locking problem is just in the fb helper paths, because it's outside of
the atomic path and could conflict with an atomic update at the same time?
So only that one should get the vmap_local treatment, everything else
should keep the normal vmap treatment.
Kind of responding to all your comment on the driver changes:

These drivers only require short-term mappings, so using vmap_local would be
the natural choice. For SHMEM helpers, it's mostly a cosmetic thing. For
VRAM helpers, I was hoping to remove the vmap/vunmap helpers entirely. One
cannot really map the BOs for the long-term, so not having the helpers at
all would make sense.

But reading all your comments on the driver patches, I'd rather not update
the drivers here but later convert them to use prepare_fb/cleanup_fb in the
correct way.
Ack from me on this plan. I think I got all the other patches with an r-b
or ack?
-Daniel

Best regards
Thomas

quoted
-Daniel
quoted
---
  drivers/gpu/drm/vboxvideo/vbox_mode.c | 15 +++++++++------
  1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
index dbc0dd53c69e..215b37c78c10 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
@@ -381,7 +381,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  		container_of(plane->dev, struct vbox_private, ddev);
  	struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
  	struct drm_framebuffer *fb = plane->state->fb;
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *obj = fb->obj[0];
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(obj);
  	u32 width = plane->state->crtc_w;
  	u32 height = plane->state->crtc_h;
  	size_t data_size, mask_size;
@@ -401,11 +402,12 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  	vbox_crtc->cursor_enabled = true;
-	ret = drm_gem_vram_vmap(gbo, &map);
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
  	if (ret) {
-		/*
-		 * BUG: we should have pinned the BO in prepare_fb().
-		 */
+		dma_resv_unlock(obj->resv);
  		mutex_unlock(&vbox->hw_mutex);
  		DRM_WARN("Could not map cursor bo, skipping update\n");
  		return;
@@ -421,7 +423,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
  	data_size = width * height * 4 + mask_size;
  	copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
  	flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
  		VBOX_MOUSE_POINTER_ALPHA;
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization





  

    
Re: [PATCH v4 11/13] drm/vboxvideo: Use drm_gem_vram_vmap_local() in cursor update

    

      From: Thomas Zimmermann <tzimmermann@suse.de>

      Date: 2021-01-12 09:54:27 
    

  

  
Hi

Am 12.01.21 um 10:17 schrieb Daniel Vetter:
On Tue, Jan 12, 2021 at 08:54:02AM +0100, Thomas Zimmermann wrote:
quoted
Hi

Am 11.01.21 um 18:06 schrieb Daniel Vetter:
quoted
On Fri, Jan 08, 2021 at 10:43:38AM +0100, Thomas Zimmermann wrote:
quoted
Cursor updates in vboxvideo require a short-term mapping of the
source BO. Use drm_gem_vram_vmap_local() and avoid the pinning
operations.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
All these drivers patches break the dma_resv_lock vs
dma_fence_begin/end_signalling nesting rules, so this doesn't work.

Generally this is what the prepare/cleanup_fb hooks are for, that's where
mappings (including vmaps) are meant to be set up, permanently.

I'm kinda not clear on why we need all these changes, I thought the
locking problem is just in the fb helper paths, because it's outside of
the atomic path and could conflict with an atomic update at the same time?
So only that one should get the vmap_local treatment, everything else
should keep the normal vmap treatment.
Kind of responding to all your comment on the driver changes:

These drivers only require short-term mappings, so using vmap_local would be
the natural choice. For SHMEM helpers, it's mostly a cosmetic thing. For
VRAM helpers, I was hoping to remove the vmap/vunmap helpers entirely. One
cannot really map the BOs for the long-term, so not having the helpers at
all would make sense.

But reading all your comments on the driver patches, I'd rather not update
the drivers here but later convert them to use prepare_fb/cleanup_fb in the
correct way.
Ack from me on this plan. I think I got all the other patches with an r-b
or ack?
The shmem patch needs an update from my side.

Best regards
Thomas

-Daniel

quoted
Best regards
Thomas

quoted
-Daniel
quoted
---
   drivers/gpu/drm/vboxvideo/vbox_mode.c | 15 +++++++++------
   1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/vboxvideo/vbox_mode.c b/drivers/gpu/drm/vboxvideo/vbox_mode.c
index dbc0dd53c69e..215b37c78c10 100644
--- a/drivers/gpu/drm/vboxvideo/vbox_mode.c
+++ b/drivers/gpu/drm/vboxvideo/vbox_mode.c
@@ -381,7 +381,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
   		container_of(plane->dev, struct vbox_private, ddev);
   	struct vbox_crtc *vbox_crtc = to_vbox_crtc(plane->state->crtc);
   	struct drm_framebuffer *fb = plane->state->fb;
-	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(fb->obj[0]);
+	struct drm_gem_object *obj = fb->obj[0];
+	struct drm_gem_vram_object *gbo = drm_gem_vram_of_gem(obj);
   	u32 width = plane->state->crtc_w;
   	u32 height = plane->state->crtc_h;
   	size_t data_size, mask_size;
@@ -401,11 +402,12 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
   	vbox_crtc->cursor_enabled = true;
-	ret = drm_gem_vram_vmap(gbo, &map);
+	ret = dma_resv_lock(obj->resv, NULL);
+	if (ret)
+		return;
+	ret = drm_gem_vram_vmap_local(gbo, &map);
   	if (ret) {
-		/*
-		 * BUG: we should have pinned the BO in prepare_fb().
-		 */
+		dma_resv_unlock(obj->resv);
   		mutex_unlock(&vbox->hw_mutex);
   		DRM_WARN("Could not map cursor bo, skipping update\n");
   		return;
@@ -421,7 +423,8 @@ static void vbox_cursor_atomic_update(struct drm_plane *plane,
   	data_size = width * height * 4 + mask_size;
   	copy_cursor_image(src, vbox->cursor_data, width, height, mask_size);
-	drm_gem_vram_vunmap(gbo, &map);
+	drm_gem_vram_vunmap_local(gbo, &map);
+	dma_resv_unlock(obj->resv);
   	flags = VBOX_MOUSE_POINTER_VISIBLE | VBOX_MOUSE_POINTER_SHAPE |
   		VBOX_MOUSE_POINTER_ALPHA;
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer






  

    
Re: [PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

    

      From: Thomas Zimmermann <tzimmermann@suse.de>

      Date: 2021-01-12 13:12:45 
    

  

  
Hi

Am 11.01.21 um 17:50 schrieb Daniel Vetter:
On Fri, Jan 08, 2021 at 10:43:31AM +0100, Thomas Zimmermann wrote:
quoted
Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
  include/drm/drm_gem_shmem_helper.h     |  2 +
  2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
  	.get_sg_table = drm_gem_shmem_get_sg_table,
  	.vmap = drm_gem_shmem_vmap,
  	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
  	.mmap = drm_gem_shmem_mmap,
  };
  
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
  }
  EXPORT_SYMBOL(drm_gem_shmem_unpin);
  
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
This is a bit spaghetti and also has the problem that we're not changing
shmem->vmap_use_count under different locks, depending upon which path
we're taking.

I think the cleanest would be if we pull the if (import_attach) case out
of the _locked() version completely, for all cases, and also outside of
the shmem->vmap_lock. This means no caching of vmaps in the shmem layer
anymore for imported buffers, but this is no longer a problem: We cache
them in the exporters instead (I think at least, if not maybe need to fix
that where it's expensive).
If we do that, what protects shmem->vaddr from concurrent access near 
line 281? would it be kept NULL then?

Also, we have some stats in debugfs (see drm_gem_shmem_print_info) which 
would be incorrect (or misleading at least).

Given all that, would it be possible to remove vmap_lock in favor of 
taking the resv lock in vmap/vunmap?

Best regards
Thomas

Other option would be to unly pull it out for the _vmap_local case, but
that's a bit ugly because no longer symmetrical in the various paths.

quoted
  {
  	struct drm_gem_object *obj = &shmem->base;
  	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	}
  
  	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
  		if (!ret) {
  			if (WARN_ON(map->is_iomem)) {
  				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	return ret;
  }
  
-/*
+/**
   * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	ret = mutex_lock_interruptible(&shmem->vmap_lock);
  	if (ret)
  		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_gem_shmem_vmap);
  
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
So for the other callbacks I tried to make sure we have different entry
points for this, since it's not really the same thing and because of the
locking mess we have with dma_resv_lock vs various pre-existing local
locking scheme, it's easy to get a mess.

I think the super clean version here would be to also export just the
internal stuff for the ->v(un)map_local hooks, but that's maybe a bit too
much boilerplate for no real gain.
-Daniel

quoted
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
  static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
  {
  	struct drm_gem_object *obj = &shmem->base;
  
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  		return;
  
  	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
  	else
  		vunmap(shmem->vaddr);
  
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  	drm_gem_shmem_put_pages(shmem);
  }
  
-/*
+/**
   * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  
  	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  }
  EXPORT_SYMBOL(drm_gem_shmem_vunmap);
  
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
  struct drm_gem_shmem_object *
  drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
  				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
  int drm_gem_shmem_pin(struct drm_gem_object *obj);
  void drm_gem_shmem_unpin(struct drm_gem_object *obj);
  int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  
  int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
  
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer






  

    
Re: [PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

    

      From: Daniel Vetter <hidden>

      Date: 2021-01-12 14:17:07 
    

  

  
On Tue, Jan 12, 2021 at 02:11:24PM +0100, Thomas Zimmermann wrote:
Hi

Am 11.01.21 um 17:50 schrieb Daniel Vetter:
quoted
On Fri, Jan 08, 2021 at 10:43:31AM +0100, Thomas Zimmermann wrote:
quoted
Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
  include/drm/drm_gem_shmem_helper.h     |  2 +
  2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
  	.get_sg_table = drm_gem_shmem_get_sg_table,
  	.vmap = drm_gem_shmem_vmap,
  	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
  	.mmap = drm_gem_shmem_mmap,
  };
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
  }
  EXPORT_SYMBOL(drm_gem_shmem_unpin);
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
This is a bit spaghetti and also has the problem that we're not changing
shmem->vmap_use_count under different locks, depending upon which path
we're taking.

I think the cleanest would be if we pull the if (import_attach) case out
of the _locked() version completely, for all cases, and also outside of
the shmem->vmap_lock. This means no caching of vmaps in the shmem layer
anymore for imported buffers, but this is no longer a problem: We cache
them in the exporters instead (I think at least, if not maybe need to fix
that where it's expensive).
If we do that, what protects shmem->vaddr from concurrent access near line
281? would it be kept NULL then?

Also, we have some stats in debugfs (see drm_gem_shmem_print_info) which
would be incorrect (or misleading at least).
We'd need to disable all that for pass-through vmap of imported objects.

Given all that, would it be possible to remove vmap_lock in favor of taking
the resv lock in vmap/vunmap?
All possible (and imo long-term desirable), the trouble is in rolling it
out. I've looked at rolling out dma_resv as the one and only lock for
shmem helpers before, and gave up. Exynos is the worst (but not the only)
offender:
- it has it's own per-object lock
- that per-object lock is taken most often before calling into various
  vfuncs, which means for a gradual transition the dma_resv lock would
  nest within that existing per-object lock (until we've completely
  replaced it)
- but exynos also uses dma_resv already as an outermost lock in its
  command submission path

iow as soon as you add dma_resv_lock anywhere in shmem helpers, we've
angered lockdep with a deadlock.

That means the only path I think is feasible is adding dma_resv lock to
all drivers paths first, _outside_ of any existing driver specific
per-object locks. Then remove the driver-specific object locks, and only
then can we sprinkle dma_resv_assert_locked all over shmem helpers.

Ofc any driver without per-driver locks of their own could directly switch
over to dma_resv lock, but until we've converted over all the drivers with
their own locking shmem helpers would be stuck where they are right now.

I gave up :-/ But maybe if you only try to tackle vmap it might be
feasible, since a lot fewer callers.

Cheers, Daniel

Best regards
Thomas

quoted
Other option would be to unly pull it out for the _vmap_local case, but
that's a bit ugly because no longer symmetrical in the various paths.

quoted
  {
  	struct drm_gem_object *obj = &shmem->base;
  	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	}
  	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
  		if (!ret) {
  			if (WARN_ON(map->is_iomem)) {
  				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	return ret;
  }
-/*
+/**
   * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	ret = mutex_lock_interruptible(&shmem->vmap_lock);
  	if (ret)
  		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  	return ret;
  }
  EXPORT_SYMBOL(drm_gem_shmem_vmap);
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
So for the other callbacks I tried to make sure we have different entry
points for this, since it's not really the same thing and because of the
locking mess we have with dma_resv_lock vs various pre-existing local
locking scheme, it's easy to get a mess.

I think the super clean version here would be to also export just the
internal stuff for the ->v(un)map_local hooks, but that's maybe a bit too
much boilerplate for no real gain.
-Daniel

quoted
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
  static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
  {
  	struct drm_gem_object *obj = &shmem->base;
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  		return;
  	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
  	else
  		vunmap(shmem->vaddr);
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  	drm_gem_shmem_put_pages(shmem);
  }
-/*
+/**
   * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  }
  EXPORT_SYMBOL(drm_gem_shmem_vunmap);
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
  struct drm_gem_shmem_object *
  drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
  				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
  int drm_gem_shmem_pin(struct drm_gem_object *obj);
  void drm_gem_shmem_unpin(struct drm_gem_object *obj);
  int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization





  

    
Re: [PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

    

      From: Thomas Zimmermann <tzimmermann@suse.de>

      Date: 2021-01-27 12:12:21 
    

  

  
Hi

Am 11.01.21 um 17:50 schrieb Daniel Vetter:
On Fri, Jan 08, 2021 at 10:43:31AM +0100, Thomas Zimmermann wrote:
quoted
Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
  include/drm/drm_gem_shmem_helper.h     |  2 +
  2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
  	.get_sg_table = drm_gem_shmem_get_sg_table,
  	.vmap = drm_gem_shmem_vmap,
  	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
  	.mmap = drm_gem_shmem_mmap,
  };
  
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
  }
  EXPORT_SYMBOL(drm_gem_shmem_unpin);
  
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
This is a bit spaghetti and also has the problem that we're not changing
shmem->vmap_use_count under different locks, depending upon which path
we're taking.

I think the cleanest would be if we pull the if (import_attach) case out
of the _locked() version completely, for all cases, and also outside of
the shmem->vmap_lock. This means no caching of vmaps in the shmem layer
anymore for imported buffers, but this is no longer a problem: We cache
them in the exporters instead (I think at least, if not maybe need to fix
that where it's expensive).
There's no vmap refcounting in amdgpu AFAICT. So importing pages from 
there into an SHMEM object has the potential of breaking. IIRC same fro 
radeon and nouveau.

So I'm somewhat reluctant to making this change. I guess I'll look 
elsewhere first to fix some of the locking issues (e.g., my recent ast 
cursor patches).

Best regards
Thomas

Other option would be to unly pull it out for the _vmap_local case, but
that's a bit ugly because no longer symmetrical in the various paths.

quoted
  {
  	struct drm_gem_object *obj = &shmem->base;
  	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	}
  
  	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
  		if (!ret) {
  			if (WARN_ON(map->is_iomem)) {
  				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	return ret;
  }
  
-/*
+/**
   * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	ret = mutex_lock_interruptible(&shmem->vmap_lock);
  	if (ret)
  		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  
  	return ret;
  }
  EXPORT_SYMBOL(drm_gem_shmem_vmap);
  
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
So for the other callbacks I tried to make sure we have different entry
points for this, since it's not really the same thing and because of the
locking mess we have with dma_resv_lock vs various pre-existing local
locking scheme, it's easy to get a mess.

I think the super clean version here would be to also export just the
internal stuff for the ->v(un)map_local hooks, but that's maybe a bit too
much boilerplate for no real gain.
-Daniel

quoted
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
  static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
  {
  	struct drm_gem_object *obj = &shmem->base;
  
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  		return;
  
  	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
  	else
  		vunmap(shmem->vaddr);
  
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  	drm_gem_shmem_put_pages(shmem);
  }
  
-/*
+/**
   * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  
  	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  }
  EXPORT_SYMBOL(drm_gem_shmem_vunmap);
  
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
  struct drm_gem_shmem_object *
  drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
  				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
  int drm_gem_shmem_pin(struct drm_gem_object *obj);
  void drm_gem_shmem_unpin(struct drm_gem_object *obj);
  int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  
  int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
  
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer






  

    
Re: [PATCH v4 04/13] drm/shmem-helper: Provide a vmap function for short-term mappings

    

      From: Daniel Vetter <hidden>

      Date: 2021-02-02 17:43:20 
    

  

  
On Wed, Jan 27, 2021 at 01:08:05PM +0100, Thomas Zimmermann wrote:
Hi

Am 11.01.21 um 17:50 schrieb Daniel Vetter:
quoted
On Fri, Jan 08, 2021 at 10:43:31AM +0100, Thomas Zimmermann wrote:
quoted
Implementations of the vmap/vunmap GEM callbacks may perform pinning
of the BO and may acquire the associated reservation object's lock.
Callers that only require a mapping of the contained memory can thus
interfere with other tasks that require exact pinning, such as scanout.
This is less of an issue with private SHMEM buffers, but may happen
with imported ones.

Therefore provide the new interfaces drm_gem_shmem_vmap_local() and
drm_gem_shmem_vunmap_local(), which only perform the vmap/vunmap
operations. Callers have to hold the reservation lock while the mapping
persists.

This patch also connects GEM SHMEM helpers to GEM object functions with
equivalent functionality.

v4:
	* call dma_buf_{vmap,vunmap}_local() where necessary (Daniel)
	* move driver changes into separate patches (Daniel)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
---
  drivers/gpu/drm/drm_gem_shmem_helper.c | 90 +++++++++++++++++++++++---
  include/drm/drm_gem_shmem_helper.h     |  2 +
  2 files changed, 84 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c
index 9825c378dfa6..298832b2b43b 100644
--- a/drivers/gpu/drm/drm_gem_shmem_helper.c
+++ b/drivers/gpu/drm/drm_gem_shmem_helper.c
@@ -32,6 +32,8 @@ static const struct drm_gem_object_funcs drm_gem_shmem_funcs = {
  	.get_sg_table = drm_gem_shmem_get_sg_table,
  	.vmap = drm_gem_shmem_vmap,
  	.vunmap = drm_gem_shmem_vunmap,
+	.vmap_local = drm_gem_shmem_vmap_local,
+	.vunmap_local = drm_gem_shmem_vunmap_local,
  	.mmap = drm_gem_shmem_mmap,
  };
@@ -261,7 +263,8 @@ void drm_gem_shmem_unpin(struct drm_gem_object *obj)
  }
  EXPORT_SYMBOL(drm_gem_shmem_unpin);
-static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map)
+static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct dma_buf_map *map,
+				     bool local)
This is a bit spaghetti and also has the problem that we're not changing
shmem->vmap_use_count under different locks, depending upon which path
we're taking.

I think the cleanest would be if we pull the if (import_attach) case out
of the _locked() version completely, for all cases, and also outside of
the shmem->vmap_lock. This means no caching of vmaps in the shmem layer
anymore for imported buffers, but this is no longer a problem: We cache
them in the exporters instead (I think at least, if not maybe need to fix
that where it's expensive).
There's no vmap refcounting in amdgpu AFAICT. So importing pages from there
into an SHMEM object has the potential of breaking. IIRC same fro radeon and
nouveau.
As long as the pinning is refcounted I think it should be fine, it's just
that if you have multiple vmaps (e.g. 2 udl devices plugged in) we'll set
up 2 vmaps. Which is a point pointless, but not really harmful. At least
on 64bit where there's enough virtual address space.

So I'm somewhat reluctant to making this change. I guess I'll look elsewhere
first to fix some of the locking issues (e.g., my recent ast cursor
patches).
If this would break for amdgpu/radeon/nouveau then we already have a bug,
since 2 udl devices can provoke this issue already as-is. So I don't think
this should be a blocker.
-Daniel

Best regards
Thomas

quoted
Other option would be to unly pull it out for the _vmap_local case, but
that's a bit ugly because no longer symmetrical in the various paths.

quoted
  {
  	struct drm_gem_object *obj = &shmem->base;
  	int ret = 0;
@@ -272,7 +275,10 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	}
  	if (obj->import_attach) {
-		ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
+		if (local)
+			ret = dma_buf_vmap_local(obj->import_attach->dmabuf, map);
+		else
+			ret = dma_buf_vmap(obj->import_attach->dmabuf, map);
  		if (!ret) {
  			if (WARN_ON(map->is_iomem)) {
  				ret = -EIO;
@@ -313,7 +319,7 @@ static int drm_gem_shmem_vmap_locked(struct drm_gem_shmem_object *shmem, struct
  	return ret;
  }
-/*
+/**
   * drm_gem_shmem_vmap - Create a virtual mapping for a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
@@ -339,15 +345,53 @@ int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	ret = mutex_lock_interruptible(&shmem->vmap_lock);
  	if (ret)
  		return ret;
-	ret = drm_gem_shmem_vmap_locked(shmem, map);
+	ret = drm_gem_shmem_vmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  	return ret;
  }
  EXPORT_SYMBOL(drm_gem_shmem_vmap);
+/**
+ * drm_gem_shmem_vmap_local - Create a virtual mapping for a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Returns the kernel virtual address of the SHMEM GEM object's backing
+ *       store.
+ *
+ * This function makes sure that a contiguous kernel virtual address mapping
+ * exists for the buffer backing the shmem GEM object.
+ *
+ * The function is called with the BO's reservation object locked. Callers must
+ * hold the lock until after unmapping the buffer.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local. But
+ * it can also be called by drivers directly, in which case it will hide the
+ * differences between dma-buf imported and natively allocated objects.
So for the other callbacks I tried to make sure we have different entry
points for this, since it's not really the same thing and because of the
locking mess we have with dma_resv_lock vs various pre-existing local
locking scheme, it's easy to get a mess.

I think the super clean version here would be to also export just the
internal stuff for the ->v(un)map_local hooks, but that's maybe a bit too
much boilerplate for no real gain.
-Daniel

quoted
+ *
+ * Acquired mappings should be cleaned up by calling drm_gem_shmem_vunmap_local().
+ *
+ * Returns:
+ * 0 on success or a negative error code on failure.
+ */
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+	int ret;
+
+	dma_resv_assert_held(obj->resv);
+
+	ret = mutex_lock_interruptible(&shmem->vmap_lock);
+	if (ret)
+		return ret;
+	ret = drm_gem_shmem_vmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_shmem_vmap_local);
+
  static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
-					struct dma_buf_map *map)
+					struct dma_buf_map *map, bool local)
  {
  	struct drm_gem_object *obj = &shmem->base;
@@ -358,7 +402,10 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  		return;
  	if (obj->import_attach)
-		dma_buf_vunmap(obj->import_attach->dmabuf, map);
+		if (local)
+			dma_buf_vunmap_local(obj->import_attach->dmabuf, map);
+		else
+			dma_buf_vunmap(obj->import_attach->dmabuf, map);
  	else
  		vunmap(shmem->vaddr);
@@ -366,7 +413,7 @@ static void drm_gem_shmem_vunmap_locked(struct drm_gem_shmem_object *shmem,
  	drm_gem_shmem_put_pages(shmem);
  }
-/*
+/**
   * drm_gem_shmem_vunmap - Unmap a virtual mapping fo a shmem GEM object
   * @shmem: shmem GEM object
   * @map: Kernel virtual address where the SHMEM GEM object was mapped
@@ -384,11 +431,38 @@ void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map)
  	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
  	mutex_lock(&shmem->vmap_lock);
-	drm_gem_shmem_vunmap_locked(shmem, map);
+	drm_gem_shmem_vunmap_locked(shmem, map, false);
  	mutex_unlock(&shmem->vmap_lock);
  }
  EXPORT_SYMBOL(drm_gem_shmem_vunmap);
+/**
+ * drm_gem_shmem_vunmap_local - Unmap a virtual mapping fo a shmem GEM object
+ * @shmem: shmem GEM object
+ * @map: Kernel virtual address where the SHMEM GEM object was mapped
+ *
+ * This function cleans up a kernel virtual address mapping acquired by
+ * drm_gem_shmem_vmap_local(). The mapping is only removed when the use count
+ * drops to zero.
+ *
+ * The function is called with the BO's reservation object locked.
+ *
+ * This function can be used to implement &drm_gem_object_funcs.vmap_local.
+ * But it can also be called by drivers directly, in which case it will hide
+ * the differences between dma-buf imported and natively allocated objects.
+ */
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map)
+{
+	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
+
+	dma_resv_assert_held(obj->resv);
+
+	mutex_lock(&shmem->vmap_lock);
+	drm_gem_shmem_vunmap_locked(shmem, map, true);
+	mutex_unlock(&shmem->vmap_lock);
+}
+EXPORT_SYMBOL(drm_gem_shmem_vunmap_local);
+
  struct drm_gem_shmem_object *
  drm_gem_shmem_create_with_handle(struct drm_file *file_priv,
  				 struct drm_device *dev, size_t size,
diff --git a/include/drm/drm_gem_shmem_helper.h b/include/drm/drm_gem_shmem_helper.h
index 434328d8a0d9..3f59bdf749aa 100644
--- a/include/drm/drm_gem_shmem_helper.h
+++ b/include/drm/drm_gem_shmem_helper.h
@@ -114,7 +114,9 @@ void drm_gem_shmem_put_pages(struct drm_gem_shmem_object *shmem);
  int drm_gem_shmem_pin(struct drm_gem_object *obj);
  void drm_gem_shmem_unpin(struct drm_gem_object *obj);
  int drm_gem_shmem_vmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+int drm_gem_shmem_vmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  void drm_gem_shmem_vunmap(struct drm_gem_object *obj, struct dma_buf_map *map);
+void drm_gem_shmem_vunmap_local(struct drm_gem_object *obj, struct dma_buf_map *map);
  int drm_gem_shmem_madvise(struct drm_gem_object *obj, int madv);
-- 
2.29.2
-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer



-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
_______________________________________________
Virtualization mailing list
Virtualization@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/virtualization




    
  

  
    

      

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