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| author | Greg Kurz <groug@kaod.org> | 2018-03-20 11:44:56 +0100 |
|---|---|---|
| committer | Jason Wang <jasowang@redhat.com> | 2018-03-26 14:49:17 +0800 |
| commit | 94b52958b77a2a040564cf7ed716d3a9545d94e5 (patch) | |
| tree | 0d19db87e871e8c65407f5bf35b34d3d8303e3d6 /hw/net/virtio-net.c | |
| parent | 7b1db0908d88f0c9cfac24e214ff72a860692e23 (diff) | |
| download | focaccia-qemu-94b52958b77a2a040564cf7ed716d3a9545d94e5.tar.gz focaccia-qemu-94b52958b77a2a040564cf7ed716d3a9545d94e5.zip | |
virtio_net: flush uncompleted TX on reset
If the backend could not transmit a packet right away for some reason, the packet is queued for asynchronous sending. The corresponding vq element is tracked in the async_tx.elem field of the VirtIONetQueue, for later freeing when the transmission is complete. If a reset happens before completion, virtio_net_tx_complete() will push async_tx.elem back to the guest anyway, and we end up with the inuse flag of the vq being equal to -1. The next call to virtqueue_pop() is then likely to fail with "Virtqueue size exceeded". This can be reproduced easily by starting a guest with an hubport backend that is not connected to a functional network, eg, -device virtio-net-pci,netdev=hub0 -netdev hubport,id=hub0,hubid=0 and no other -netdev hubport,hubid=0 on the command line. The appropriate fix is to ensure that such an asynchronous transmission cannot survive a device reset. So for all queues, we first try to send the packet again, and eventually we purge it if the backend still could not deliver it. CC: qemu-stable@nongnu.org Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com> Buglink: https://github.com/open-power-host-os/qemu/issues/37 Signed-off-by: Greg Kurz <groug@kaod.org> Tested-by: R. Nageswara Sastry <nasastry@in.ibm.com> Signed-off-by: Jason Wang <jasowang@redhat.com>
Diffstat (limited to 'hw/net/virtio-net.c')
| -rw-r--r-- | hw/net/virtio-net.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c index 67ad38cfe4..90502fca7c 100644 --- a/hw/net/virtio-net.c +++ b/hw/net/virtio-net.c @@ -427,6 +427,7 @@ static RxFilterInfo *virtio_net_query_rxfilter(NetClientState *nc) static void virtio_net_reset(VirtIODevice *vdev) { VirtIONet *n = VIRTIO_NET(vdev); + int i; /* Reset back to compatibility mode */ n->promisc = 1; @@ -450,6 +451,16 @@ static void virtio_net_reset(VirtIODevice *vdev) memcpy(&n->mac[0], &n->nic->conf->macaddr, sizeof(n->mac)); qemu_format_nic_info_str(qemu_get_queue(n->nic), n->mac); memset(n->vlans, 0, MAX_VLAN >> 3); + + /* Flush any async TX */ + for (i = 0; i < n->max_queues; i++) { + NetClientState *nc = qemu_get_subqueue(n->nic, i); + + if (nc->peer) { + qemu_flush_or_purge_queued_packets(nc->peer, true); + assert(!virtio_net_get_subqueue(nc)->async_tx.elem); + } + } } static void peer_test_vnet_hdr(VirtIONet *n) |