From: David Riley Date: Mon, 10 Jun 2019 21:18:10 +0000 (-0700) Subject: drm/virtio: Add memory barriers for capset cache. X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=9ff3a5c88e1f1ab17a31402b96d45abe14aab9d7;p=linux.git drm/virtio: Add memory barriers for capset cache. 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 Link: http://patchwork.freedesktop.org/patch/msgid/20190610211810.253227-5-davidriley@chromium.org Signed-off-by: Gerd Hoffmann --- diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c index 9f43b160e1bb7..c0ba1ead740f4 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -540,6 +540,9 @@ copy_exit: if (!ret) return -EBUSY; + /* is_valid check must proceed before copy of the cache entry. */ + smp_rmb(); + ptr = cache_ent->caps_cache; if (copy_to_user(u64_to_user_ptr(args->addr), ptr, size)) diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 5de38b2ee9acd..6c1a90717535d 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -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)) { memcpy(cache_ent->caps_cache, resp->capset_data, cache_ent->size); + /* Copy must occur before is_valid is signalled. */ + smp_wmb(); atomic_set(&cache_ent->is_valid, 1); break; }