virtio-gpu uses cached mappings. shmem helpers use writecombine though.
So roll our own mmap function, wrapping drm_gem_shmem_mmap(), to tweak
vm_page_prot accordingly.
Reported-by: Gurchetan Singh <gurchetansingh@xxxxxxxxxxxx>
Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
drivers/gpu/drm/virtio/virtgpu_object.c | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/virtio/virtgpu_object.c b/drivers/gpu/drm/virtio/virtgpu_object.c
index 017a9e0fc3bb..158610902054 100644
--- a/drivers/gpu/drm/virtio/virtgpu_object.c
+++ b/drivers/gpu/drm/virtio/virtgpu_object.c
@@ -75,6 +75,22 @@ static void virtio_gpu_free_object(struct drm_gem_object *obj)
drm_gem_shmem_free_object(obj);
}
+static int virtio_gpu_gem_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+ pgprot_t prot;
+ int ret;
+
+ ret = drm_gem_shmem_mmap(obj, vma);
+ if (ret < 0)
+ return ret;
+
+ /* virtio-gpu needs normal caching, so clear writecombine */
+ prot = vm_get_page_prot(vma->vm_flags);
+ prot = pgprot_decrypted(prot);
+ vma->vm_page_prot = prot;
+ return 0;
+}
+
static const struct drm_gem_object_funcs virtio_gpu_gem_funcs = {
.free = virtio_gpu_free_object,
.open = virtio_gpu_gem_object_open,
@@ -86,7 +102,7 @@ static const struct drm_gem_object_funcs virtio_gpu_gem_funcs = {
.get_sg_table = drm_gem_shmem_get_sg_table,
.vmap = drm_gem_shmem_vmap,
.vunmap = drm_gem_shmem_vunmap,
- .mmap = &drm_gem_shmem_mmap,
+ .mmap = &virtio_gpu_gem_mmap,
};
struct drm_gem_object *virtio_gpu_create_object(struct drm_device *dev,
--
2.18.1
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