From 6f8be29ec17d44496b9ed67599bceaaba72d1864 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Mon, 1 May 2023 19:04:09 -0400 Subject: [PATCH] vhost-user: send SET_STATUS 0 after GET_VRING_BASE MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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, }; -- 2.30.2