From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40894) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eHiKz-00078n-4f for qemu-devel@nongnu.org; Wed, 22 Nov 2017 22:38:05 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eHiKu-000218-Je for qemu-devel@nongnu.org; Wed, 22 Nov 2017 22:38:05 -0500 From: Jason Wang Date: Thu, 23 Nov 2017 11:37:46 +0800 Message-Id: <1511408266-4139-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PATCH for 2.11] virtio-net: don't touch virtqueue if vm is stopped List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mst@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org Cc: Yuri Benditovich , Paolo Bonzini , Stefan Hajnoczi , qemu-stable@nongnu.org Guest state should not be touched if VM is stopped, unfortunately we didn't check running state and tried to drain tx queue unconditionally in virtio_net_set_status(). A crash was then noticed as a migration destination when user type quit after virtqueue state is loaded but before region cache is initialized. In this case, virtio_net_drop_tx_queue_data() tries to access the uninitialized region cache. Fix this by only dropping tx queue data when vm is running. Fixes: 283e2c2adcb80 ("net: virtio-net discards TX data after link down") Cc: Yuri Benditovich Cc: Paolo Bonzini Cc: Stefan Hajnoczi Cc: Michael S. Tsirkin Cc: qemu-stable@nongnu.org Signed-off-by: Jason Wang --- hw/net/virtio-net.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 150fd07..38674b0 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -288,7 +288,8 @@ static void virtio_net_set_status(struct VirtIODevice *vdev, uint8_t status) qemu_bh_cancel(q->tx_bh); } if ((n->status & VIRTIO_NET_S_LINK_UP) == 0 && - (queue_status & VIRTIO_CONFIG_S_DRIVER_OK)) { + (queue_status & VIRTIO_CONFIG_S_DRIVER_OK) && + vdev->vm_running) { /* if tx is waiting we are likely have some packets in tx queue * and disabled notification */ q->tx_waiting = 0; -- 2.7.4