virtio-pci: fix virtio_pci_queue_enabled()

In legacy mode, virtio_pci_queue_enabled() falls back to virtio_queue_enabled() to know if the queue is enabled. But virtio_queue_enabled() calls again virtio_pci_queue_enabled() if k->queue_enabled is set. This ends in a crash after a stack overflow. The problem can be reproduced with "-device virtio-net-pci,disable-legacy=off,disable-modern=true -net tap,vhost=on" And a look to the backtrace is very explicit: ... #4 0x000000010029a438 in virtio_queue_enabled () #5 0x0000000100497a9c in virtio_pci_queue_enabled () ... #130902 0x000000010029a460 in virtio_queue_enabled () #130903 0x0000000100497a9c in virtio_pci_queue_enabled () #130904 0x000000010029a460 in virtio_queue_enabled () #130905 0x0000000100454a20 in vhost_net_start () ... This patch fixes the problem by introducing a new function for the legacy case and calls it from virtio_pci_queue_enabled(). It also calls it from virtio_queue_enabled() to avoid code duplication. Fixes: f19bcdf ("virtio-pci: implement queue_enabled method") Cc: Jason Wang <[email protected]> Cc: Cindy Lu <[email protected]> CC: Michael S. Tsirkin <[email protected]> Signed-off-by: Laurent Vivier <[email protected]> Message-Id: <[email protected]> Reviewed-by: Michael S. Tsirkin <[email protected]> Signed-off-by: Michael S. Tsirkin <[email protected]>
OSLL · Jul 27, 2020 · 0c9753e · 0c9753e
1 parent d0d8952
commit 0c9753e
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Showing 3 changed files with 8 additions and 2 deletions.
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
@@ -1116,7 +1116,7 @@ static bool virtio_pci_queue_enabled(DeviceState *d, int n)
         return proxy->vqs[vdev->queue_sel].enabled;
     }
 
-    return virtio_queue_enabled(vdev, n);
+    return virtio_queue_enabled_legacy(vdev, n);
 }
 
 static int virtio_pci_add_mem_cap(VirtIOPCIProxy *proxy,

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
@@ -3309,6 +3309,11 @@ hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n)
     return vdev->vq[n].vring.desc;
 }
 
+bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n)
+{
+    return virtio_queue_get_desc_addr(vdev, n) != 0;
+}
+
 bool virtio_queue_enabled(VirtIODevice *vdev, int n)
 {
     BusState *qbus = qdev_get_parent_bus(DEVICE(vdev));
@@ -3317,7 +3322,7 @@ bool virtio_queue_enabled(VirtIODevice *vdev, int n)
     if (k->queue_enabled) {
         return k->queue_enabled(qbus->parent, n);
     }
-    return virtio_queue_get_desc_addr(vdev, n) != 0;
+    return virtio_queue_enabled_legacy(vdev, n);
 }
 
 hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n)

diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
@@ -295,6 +295,7 @@ typedef struct VirtIORNGConf VirtIORNGConf;
                       VIRTIO_F_RING_PACKED, false)
 
 hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
+bool virtio_queue_enabled_legacy(VirtIODevice *vdev, int n);
 bool virtio_queue_enabled(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_used_addr(VirtIODevice *vdev, int n);