* David Hildenbrand (david@redhat.com) wrote:

On 10.12.18 18:12, Vivek Goyal wrote:

quoted

Instead of assuming we had the fixed bar for the cache, use the
value from the capabilities.

Signed-off-by: Dr. David Alan Gilbert <redacted>
---
 fs/fuse/virtio_fs.c | 32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/fs/fuse/virtio_fs.c b/fs/fuse/virtio_fs.c
index 60d496c16841..55bac1465536 100644
--- a/fs/fuse/virtio_fs.c
+++ b/fs/fuse/virtio_fs.c

@@ -14,11 +14,6 @@
 #include <uapi/linux/virtio_pci.h>
 #include "fuse_i.h"
 
-enum {
-	/* PCI BAR number of the virtio-fs DAX window */
-	VIRTIO_FS_WINDOW_BAR = 2,
-};
-
 /* List of virtio-fs device instances and a lock for the list */
 static DEFINE_MUTEX(virtio_fs_mutex);
 static LIST_HEAD(virtio_fs_instances);

@@ -518,7 +513,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	struct dev_pagemap *pgmap;
 	struct pci_dev *pci_dev;
 	phys_addr_t phys_addr;
-	size_t len;
+	size_t bar_len;
 	int ret;
 	u8 have_cache, cache_bar;
 	u64 cache_offset, cache_len;

@@ -551,17 +546,13 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
         }
 
 	/* TODO handle case where device doesn't expose BAR? */

For virtio-pmem we decided to not go via BARs as this would effectively
make it only usable for virtio-pci implementers. Instead, we are going
to export the applicable physical device region directly (e.g.
phys_start, phys_size in virtio config), so it is decoupled from PCI
details. Doing the same for virtio-fs would allow e.g. also virtio-ccw
to make eventually use of this.

That makes it a very odd looking PCI device;  I can see that with
virtio-pmem it makes some sense, given that it's job is to expose
arbitrary chunks of memory.

Dave

quoted

-	ret = pci_request_region(pci_dev, VIRTIO_FS_WINDOW_BAR,
-				 "virtio-fs-window");
+	ret = pci_request_region(pci_dev, cache_bar, "virtio-fs-window");
 	if (ret < 0) {
 		dev_err(&vdev->dev, "%s: failed to request window BAR\n",
 			__func__);
 		return ret;
 	}
 
-	phys_addr = pci_resource_start(pci_dev, VIRTIO_FS_WINDOW_BAR);
-	len = pci_resource_len(pci_dev, VIRTIO_FS_WINDOW_BAR);
-
 	mi = devm_kzalloc(&pci_dev->dev, sizeof(*mi), GFP_KERNEL);
 	if (!mi)
 		return -ENOMEM;

@@ -586,6 +577,17 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	pgmap->ref = &mi->ref;
 	pgmap->type = MEMORY_DEVICE_FS_DAX;
 
+	phys_addr = pci_resource_start(pci_dev, cache_bar);
+	bar_len = pci_resource_len(pci_dev, cache_bar);
+
+	if (cache_offset + cache_len > bar_len) {
+		dev_err(&vdev->dev,
+			"%s: cache bar shorter than cap offset+len\n",
+			__func__);
+		return -EINVAL;
+	}
+	phys_addr += cache_offset;
+
 	/* Ideally we would directly use the PCI BAR resource but
 	 * devm_memremap_pages() wants its own copy in pgmap.  So
 	 * initialize a struct resource from scratch (only the start

@@ -594,7 +596,7 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 	pgmap->res = (struct resource){
 		.name = "virtio-fs dax window",
 		.start = phys_addr,
-		.end = phys_addr + len,
+		.end = phys_addr + cache_len,
 	};
 
 	fs->window_kaddr = devm_memremap_pages(&pci_dev->dev, pgmap);

@@ -607,10 +609,10 @@ static int virtio_fs_setup_dax(struct virtio_device *vdev, struct virtio_fs *fs)
 		return ret;
 
 	fs->window_phys_addr = phys_addr;
-	fs->window_len = len;
+	fs->window_len = cache_len;
 
-	dev_dbg(&vdev->dev, "%s: window kaddr 0x%px phys_addr 0x%llx len %zu\n",
-		__func__, fs->window_kaddr, phys_addr, len);
+	dev_dbg(&vdev->dev, "%s: cache kaddr 0x%px phys_addr 0x%llx len %llx\n",
+		__func__, fs->window_kaddr, phys_addr, cache_len);
 
 	fs->dax_dev = alloc_dax(fs, NULL, &virtio_fs_dax_ops);
 	if (!fs->dax_dev)

-- 

Thanks,

David / dhildenb

--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK