On Wed, Dec 23, 2020 at 4:37 PM Jason Wang [off-list ref] wrote:

On 2020/12/22 下午10:52, Xie Yongji wrote:

quoted

This patch introduces a new method in the vdpa_config_ops to
support processing the raw vhost memory mapping message in the
vDPA device driver.

Signed-off-by: Xie Yongji <redacted>
---
  drivers/vhost/vdpa.c | 5 ++++-
  include/linux/vdpa.h | 7 +++++++
  2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c
index 448be7875b6d..ccbb391e38be 100644
--- a/drivers/vhost/vdpa.c
+++ b/drivers/vhost/vdpa.c

@@ -728,6 +728,9 @@ static int vhost_vdpa_process_iotlb_msg(struct vhost_dev *dev,
      if (r)
              return r;

+     if (ops->process_iotlb_msg)
+             return ops->process_iotlb_msg(vdpa, msg);
+
      switch (msg->type) {
      case VHOST_IOTLB_UPDATE:
              r = vhost_vdpa_process_iotlb_update(v, msg);

@@ -770,7 +773,7 @@ static int vhost_vdpa_alloc_domain(struct vhost_vdpa *v)
      int ret;

      /* Device want to do DMA by itself */
-     if (ops->set_map || ops->dma_map)
+     if (ops->set_map || ops->dma_map || ops->process_iotlb_msg)
              return 0;

      bus = dma_dev->bus;

diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 656fe264234e..7bccedf22f4b 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h

@@ -5,6 +5,7 @@
  #include <linux/kernel.h>
  #include <linux/device.h>
  #include <linux/interrupt.h>
+#include <linux/vhost_types.h>
  #include <linux/vhost_iotlb.h>
  #include <net/genetlink.h>

@@ -172,6 +173,10 @@ struct vdpa_iova_range {
   *                          @vdev: vdpa device
   *                          Returns the iova range supported by
   *                          the device.
+ * @process_iotlb_msg:               Process vhost memory mapping message (optional)
+ *                           Only used for VDUSE device now
+ *                           @vdev: vdpa device
+ *                           @msg: vhost memory mapping message
   * @set_map:                        Set device memory mapping (optional)
   *                          Needed for device that using device
   *                          specific DMA translation (on-chip IOMMU)

@@ -240,6 +245,8 @@ struct vdpa_config_ops {
      struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev);

      /* DMA ops */
+     int (*process_iotlb_msg)(struct vdpa_device *vdev,
+                              struct vhost_iotlb_msg *msg);
      int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb);
      int (*dma_map)(struct vdpa_device *vdev, u64 iova, u64 size,
                     u64 pa, u32 perm);

Is there any reason that it can't be done via dma_map/dma_unmap or set_map?

To get the shmfd, we need the vma rather than physical address. And
it's not necessary to pin the user pages in VDUSE case.

Thanks,
Yongji