The companion commit preserves ring state across VHOST_RESET_OWNER, but QEMU still issues VHOST_VSOCK_SET_RUNNING(0) before RESET_OWNER, nulling vq->private_data via vhost_vsock_drop_backends(). The fast-fail in vhost_transport_send_pkt() from 4ff28534c799 then rejects every host send with -EHOSTUNREACH until the destination calls SET_RUNNING(1) -- the entire CPR window becomes a hard outage for host AF_VSOCK clients (VSTOR-131956).
Add a cpr_paused flag set by vhost_vsock_stop() when the backend was previously live, cleared by vhost_vsock_start(). When set, vhost_transport_send_pkt() queues the skb instead of fast-failing; the existing kick of send_pkt_work in vhost_vsock_start() drains it on resume. A device that has never run keeps cpr_paused == false and the boot-time fast-fail behaviour is preserved. Set the flag before dropping backends so a concurrent sender never observes (NULL, !paused). Feature: kvm https://virtuozzo.atlassian.net/browse/VSTOR-131956 Signed-off-by: Denis V. Lunev <[email protected]> --- drivers/vhost/vsock.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index 0a518c3d1596..1d2ceec7f2e0 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -57,6 +57,7 @@ struct vhost_vsock { u32 guest_cid; bool seqpacket_allow; + bool cpr_paused; /* between stop and next start; queues sends */ }; static u32 vhost_transport_get_local_cid(void) @@ -295,7 +296,9 @@ vhost_transport_send_pkt(struct sk_buff *skb) * all the outcomes covered: if the backend becomes NULL right after the check, * vhost_transport_do_send_pkt() will check it under the mutex anyway. */ - if (unlikely(!data_race(vhost_vq_get_backend(&vsock->vqs[VSOCK_VQ_RX])))) { + /* cpr_paused: queue across CPR; else NULL backend means not ready. */ + if (unlikely(!data_race(vhost_vq_get_backend(&vsock->vqs[VSOCK_VQ_RX])) && + !READ_ONCE(vsock->cpr_paused))) { rcu_read_unlock(); kfree_skb(skb); return -EHOSTUNREACH; @@ -610,6 +613,8 @@ static int vhost_vsock_start(struct vhost_vsock *vsock) mutex_unlock(&vq->mutex); } + WRITE_ONCE(vsock->cpr_paused, false); + /* Some packets may have been queued before the device was started, * let's kick the send worker to send them. */ @@ -653,6 +658,7 @@ static void vhost_vsock_drop_backends(struct vhost_vsock *vsock) static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner) { int ret = 0; + bool was_running; mutex_lock(&vsock->dev.mutex); @@ -662,6 +668,9 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner) goto err; } + was_running = !!vhost_vq_get_backend(&vsock->vqs[VSOCK_VQ_RX]); + if (was_running) + WRITE_ONCE(vsock->cpr_paused, true); vhost_vsock_drop_backends(vsock); err: mutex_unlock(&vsock->dev.mutex); -- 2.51.0 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
