From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH AUTOSEL 4.19 027/101] drm/virtio: Add memory barriers for capset cache. Date: Fri, 19 Jul 2019 00:06:18 -0400 Message-ID: <20190719040732.17285-27-sashal@kernel.org> References: <20190719040732.17285-1-sashal@kernel.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <20190719040732.17285-1-sashal@kernel.org> Sender: stable-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: David Riley , Gerd Hoffmann , Sasha Levin , dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org List-Id: dri-devel@lists.freedesktop.org From: David Riley [ Upstream commit 9ff3a5c88e1f1ab17a31402b96d45abe14aab9d7 ] 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 Signed-off-by: Sasha Levin --- drivers/gpu/drm/virtio/virtgpu_ioctl.c | 3 +++ drivers/gpu/drm/virtio/virtgpu_vq.c | 2 ++ 2 files changed, 5 insertions(+) diff --git a/drivers/gpu/drm/virtio/virtgpu_ioctl.c b/drivers/gpu/drm/virtio/virtgpu_ioctl.c index 7bdf6f0e58a5..8d2f5ded86d6 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -528,6 +528,9 @@ static int virtio_gpu_get_caps_ioctl(struct drm_device *dev, if (!ret) return -EBUSY; + /* is_valid check must proceed before copy of the cache entry. */ + smp_rmb(); + ptr = cache_ent->caps_cache; copy_exit: diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index 020070d483d3..c8a581b1f4c4 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -588,6 +588,8 @@ 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; } -- 2.20.1