diff mbox series

[34/40] vdpa: fix network breakage after cancelling migration

Message ID 1701970793-6865-35-git-send-email-si-wei.liu@oracle.com (mailing list archive)
State New, archived
Headers show
Series vdpa-net: improve migration downtime through descriptor ASID and persistent IOTLB | expand

Commit Message

Si-Wei Liu Dec. 7, 2023, 5:39 p.m. UTC 
Fix an issue where cancellation of ongoing migration ends up
with no network connectivity.

When canceling migration, SVQ will be switched back to the
passthrough mode, but the right call fd is not programed to
the device and the svq's own call fd is still used. At the
point of this transitioning period, the shadow_vqs_enabled
hadn't been set back to false yet, causing the installation
of call fd inadvertently bypassed.

Fixes: a8ac88585da1 ("vhost: Add Shadow VirtQueue call forwarding capabilities")
Cc: Eugenio Pérez <eperezma@redhat.com>

Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>
---
 hw/virtio/vhost-vdpa.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Jason Wang Jan. 15, 2024, 3:48 a.m. UTC | #1 
On Fri, Dec 8, 2023 at 2:51 AM Si-Wei Liu <si-wei.liu@oracle.com> wrote:
>
> Fix an issue where cancellation of ongoing migration ends up
> with no network connectivity.
>
> When canceling migration, SVQ will be switched back to the
> passthrough mode, but the right call fd is not programed to
> the device and the svq's own call fd is still used. At the
> point of this transitioning period, the shadow_vqs_enabled
> hadn't been set back to false yet, causing the installation
> of call fd inadvertently bypassed.
>
> Fixes: a8ac88585da1 ("vhost: Add Shadow VirtQueue call forwarding capabilities")
> Cc: Eugenio Pérez <eperezma@redhat.com>

Let's cc stable and post this as an independent patch.

>
> Signed-off-by: Si-Wei Liu <si-wei.liu@oracle.com>

Acked-by: Jason Wang <jasowang@redhat.com>

Thanks
diff mbox series

Patch

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 4010fd9..8ba390d 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -1647,7 +1647,12 @@  static int vhost_vdpa_set_vring_call(struct vhost_dev *dev,
 
     /* Remember last call fd because we can switch to SVQ anytime. */
     vhost_svq_set_svq_call_fd(svq, file->fd);
-    if (v->shadow_vqs_enabled) {
+    /*
+     * In the event of SVQ switching to off, shadow_vqs_enabled has
+     * not been set to false yet, but the underlying call fd will
+     * switch back to the guest notifier for passthrough VQs.
+     */
+    if (v->shadow_vqs_enabled && v->shared->svq_switching >= 0) {
         return 0;
     }