From c17dffff03c6ba03633b8e009599bd3863c638fa Mon Sep 17 00:00:00 2001
From: Julia Suvorova <jusual@redhat.com>
Date: Wed, 4 Mar 2020 20:07:51 -0500
Subject: [PATCH 09/12] clean up callback when del virtqueue

RH-Author: Julia Suvorova <jusual@redhat.com>
Message-id: <20200304200754.32708-2-jusual@redhat.com>
Patchwork-id: 94152
O-Subject: [RHEL-7.9 qemu-kvm-rhev PATCH 1/4] clean up callback when del virtqueue
Bugzilla: 1721403
RH-Acked-by: Stefano Garzarella <sgarzare@redhat.com>
RH-Acked-by: Maxim Levitsky <mlevitsk@redhat.com>
RH-Acked-by: Michael S. Tsirkin <mst@redhat.com>

From: liujunjie <liujunjie23@huawei.com>

Before, we did not clear callback like handle_output when delete
the virtqueue which may result be segmentfault.
The scene is as follows:
1. Start a vm with multiqueue vhost-net,
2. then we write VIRTIO_PCI_GUEST_FEATURES in PCI configuration to
triger multiqueue disable in this vm which will delete the virtqueue.
In this step, the tx_bh is deleted but the callback virtio_net_handle_tx_bh
still exist.
3. Finally, we write VIRTIO_PCI_QUEUE_NOTIFY in PCI configuration to
notify the deleted virtqueue. In this way, virtio_net_handle_tx_bh
will be called and qemu will be crashed.

Although the way described above is uncommon, we had better reinforce it.

CC: qemu-stable@nongnu.org
Signed-off-by: liujunjie <liujunjie23@huawei.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
(cherry picked from commit 7da2d99fb9fbf30104125c061caaff330e362d74)
Signed-off-by: Jon Maloy <jmaloy.redhat.com>
---
 hw/virtio/virtio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 08a4332210..d228b9297d 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1610,6 +1610,8 @@ void virtio_del_queue(VirtIODevice *vdev, int n)
 
     vdev->vq[n].vring.num = 0;
     vdev->vq[n].vring.num_default = 0;
+    vdev->vq[n].handle_output = NULL;
+    vdev->vq[n].handle_aio_output = NULL;
 }
 
 static void virtio_set_isr(VirtIODevice *vdev, int value)
-- 
2.18.2