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vhost_user: Clear ring address on GET_VRING_BASE

GET_VRING_BASE stops the queue, clearing the call and kick fds.  However,
we don't clear vring.avail.  That means that if vu_queue_notify() is called
it won't realise the queue isn't ready and will die with an EBADFD.

We get this during migration, because for some reason, qemu reconfigures
the vhost-user device when a migration is triggered.  There's a window
between the GET_VRING_BASE and re-establishing the call fd where the
notify function can be called, causing a crash.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
This commit is contained in:
David Gibson 2025-02-15 00:08:41 +11:00 committed by Stefano Brivio
parent 71249ef3f9
commit 7c33b12086

View File

@ -732,6 +732,7 @@ static bool vu_get_vring_base_exec(struct vu_dev *vdev,
msg->hdr.size = sizeof(msg->payload.state);
vdev->vq[idx].started = false;
vdev->vq[idx].vring.avail = 0;
if (vdev->vq[idx].call_fd != -1) {
close(vdev->vq[idx].call_fd);