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Tsirkin" To: qemu-devel@nongnu.org Cc: Peter Maydell , Stefan Hajnoczi , Cindy Lu , Yajun Wu , Maxime Coquelin , Eugenio =?utf-8?B?UMOpcmV6?= Subject: [PULL 18/40] vhost-user: send SET_STATUS 0 after GET_VRING_BASE Message-ID: <6f8be29ec17d44496b9ed67599bceaaba72d1864.1684507742.git.mst@redhat.com> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Mailer: git-send-email 2.27.0.106.g8ac3dc51b1 X-Mutt-Fcc: =sent Received-SPF: pass client-ip=170.10.133.124; envelope-from=mst@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Stefan Hajnoczi Setting the VIRTIO Device Status Field to 0 resets the device. The device's state is lost, including the vring configuration. vhost-user.c currently sends SET_STATUS 0 before GET_VRING_BASE. This risks confusion about the lifetime of the vhost-user state (e.g. vring last_avail_idx) across VIRTIO device reset. Eugenio Pérez adjusted the order for vhost-vdpa.c in commit c3716f260bff ("vdpa: move vhost reset after get vring base") and in that commit description suggested doing the same for vhost-user in the future. Go ahead and adjust vhost-user.c now. I ran various online code searches to identify vhost-user backends implementing SET_STATUS. It seems only DPDK implements SET_STATUS and Yajun Wu has confirmed that it is safe to make this change. Fixes: commit 923b8921d210763359e96246a58658ac0db6c645 ("vhost-user: Support vhost_dev_start") Cc: Michael S. Tsirkin Cc: Cindy Lu Cc: Yajun Wu Signed-off-by: Stefan Hajnoczi Message-Id: <20230501230409.274178-1-stefanha@redhat.com> Reviewed-by: Maxime Coquelin Reviewed-by: Yajun Wu  Acked-by: Eugenio Pérez Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/virtio/vhost-user.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-) diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c index e5285df4ba..40974afd06 100644 --- a/hw/virtio/vhost-user.c +++ b/hw/virtio/vhost-user.c @@ -2677,7 +2677,20 @@ static int vhost_user_dev_start(struct vhost_dev *dev, bool started) VIRTIO_CONFIG_S_DRIVER | VIRTIO_CONFIG_S_DRIVER_OK); } else { - return vhost_user_set_status(dev, 0); + return 0; + } +} + +static void vhost_user_reset_status(struct vhost_dev *dev) +{ + /* Set device status only for last queue pair */ + if (dev->vq_index + dev->nvqs != dev->vq_index_end) { + return; + } + + if (virtio_has_feature(dev->protocol_features, + VHOST_USER_PROTOCOL_F_STATUS)) { + vhost_user_set_status(dev, 0); } } @@ -2716,4 +2729,5 @@ const VhostOps user_ops = { .vhost_get_inflight_fd = vhost_user_get_inflight_fd, .vhost_set_inflight_fd = vhost_user_set_inflight_fd, .vhost_dev_start = vhost_user_dev_start, + .vhost_reset_status = vhost_user_reset_status, }; -- MST