From mboxrd@z Thu Jan 1 00:00:00 1970 From: davidriley@chromium.org Subject: [PATCH 4/4] drm/virtio: Add memory barriers for capset cache. Date: Wed, 5 Jun 2019 16:44:23 -0700 Message-ID: <20190605234423.11348-4-davidriley__22539.4261231244$1559778329$gmane$org@chromium.org> References: <20190605234423.11348-1-davidriley@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190605234423.11348-1-davidriley@chromium.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org Cc: David Airlie , Daniel Vetter , linux-kernel@vger.kernel.org List-Id: virtualization@lists.linuxfoundation.org From: David Riley 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 same memory barries. Signed-off-by: David Riley --- 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 88c1ed57a3c5..502f5f7c2298 100644 --- a/drivers/gpu/drm/virtio/virtgpu_ioctl.c +++ b/drivers/gpu/drm/virtio/virtgpu_ioctl.c @@ -542,6 +542,9 @@ 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. */ + virt_rmb(); + ptr = cache_ent->caps_cache; if (copy_to_user((void __user *)(unsigned long)args->addr, ptr, size)) diff --git a/drivers/gpu/drm/virtio/virtgpu_vq.c b/drivers/gpu/drm/virtio/virtgpu_vq.c index dd5ead2541c2..b974eba4fe7d 100644 --- a/drivers/gpu/drm/virtio/virtgpu_vq.c +++ b/drivers/gpu/drm/virtio/virtgpu_vq.c @@ -583,6 +583,8 @@ 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. */ + virt_wmb(); atomic_set(&cache_ent->is_valid, 1); break; } -- 2.22.0.rc1.311.g5d7573a151-goog