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drm/virtio: Add memory barriers for capset cache.

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After data is copied to the cache entry, atomic_set is used indicate
that the data is the entry is valid without appropriate memory barriers.
Similarly the read side was missing the corresponding memory barriers.

Signed-off-by: David Riley <davidriley@chromium.org>
Link: http://patchwork.freedesktop.org/patch/msgid/20190610211810.253227-5-davidriley@chromium.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
David Riley 2019-06-10 14:18:10 -07:00 • committed by Gerd Hoffmann
parent 47b757fba2
commit 9ff3a5c88e
2 changed files with 5 additions and 0 deletions
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3
drivers/gpu/drm/virtio/virtgpu_ioctl.c
View file

@ -540,6 +540,9 @@ copy_exit:
if (!ret) if (!ret)
return -EBUSY; return -EBUSY;
/* is_valid check must proceed before copy of the cache entry. */
smp_rmb();
ptr = cache_ent->caps_cache; ptr = cache_ent->caps_cache;
if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size)) if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size))

2
drivers/gpu/drm/virtio/virtgpu_vq.c
View file

@ -593,6 +593,8 @@ static void virtio_gpu_cmd_capset_cb(struct virtio_gpu_device *vgdev,
cache_ent->id == le32_to_cpu(cmd->capset_id)) { cache_ent->id == le32_to_cpu(cmd->capset_id)) {
memcpy(cache_ent->caps_cache, resp->capset_data, memcpy(cache_ent->caps_cache, resp->capset_data,
cache_ent->size); cache_ent->size);
/* Copy must occur before is_valid is signalled. */
smp_wmb();
atomic_set(&cache_ent->is_valid, 1); atomic_set(&cache_ent->is_valid, 1);
break; break;
} }