[PATCH 2/3] virtio-pci: Add virtio_queue_valid checks ahead of virtio_queue_get_num

["Nicholas A. Bellinger" <nab@linux-iscsi.org>]

From: Nicholas Bellinger <nab@linux-iscsi.org>

This patch adds a number of virtio_queue_valid() checks to virtio-pci
ahead of virtio_queue_get_num() usage in order to skip operation upon
the detection of an uninitialized VQ.

There is one exception in virtio_ioport_read():VIRTIO_PCI_QUEUE_NUM,
where virtio_queue_get_num() may still be called without a valid
vdev->vq[n].vring.desc physical address.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Asias He <asias@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
 hw/virtio-pci.c |   27 +++++++++++++++++++++++++++
 1 files changed, 27 insertions(+), 0 deletions(-)

diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c
index 0d67b84..231ca0c 100644
--- a/hw/virtio-pci.c
+++ b/hw/virtio-pci.c
@@ -211,6 +211,9 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
     }
 
     for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+        if (!virtio_queue_valid(proxy->vdev, n)) {
+            continue;
+        }
         if (!virtio_queue_get_num(proxy->vdev, n)) {
             continue;
         }
@@ -225,6 +228,9 @@ static void virtio_pci_start_ioeventfd(VirtIOPCIProxy *proxy)
 
 assign_error:
     while (--n >= 0) {
+        if (!virtio_queue_valid(proxy->vdev, n)) {
+            continue;
+        }
         if (!virtio_queue_get_num(proxy->vdev, n)) {
             continue;
         }
@@ -246,6 +252,9 @@ static void virtio_pci_stop_ioeventfd(VirtIOPCIProxy *proxy)
     }
 
     for (n = 0; n < VIRTIO_PCI_QUEUE_MAX; n++) {
+        if (!virtio_queue_valid(proxy->vdev, n)) {
+            continue;
+        }
         if (!virtio_queue_get_num(proxy->vdev, n)) {
             continue;
         }
@@ -546,6 +555,9 @@ static int kvm_virtio_pci_vector_use(VirtIOPCIProxy *proxy, int nvqs)
     MSIMessage msg;
 
     for (queue_no = 0; queue_no < nvqs; queue_no++) {
+        if (!virtio_queue_valid(vdev, queue_no)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -593,6 +605,9 @@ static void kvm_virtio_pci_vector_release(VirtIOPCIProxy *proxy, int nvqs)
     int queue_no;
 
     for (queue_no = 0; queue_no < nvqs; queue_no++) {
+        if (!virtio_queue_valid(vdev, queue_no)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -665,6 +680,9 @@ static int kvm_virtio_pci_vector_unmask(PCIDevice *dev, unsigned vector,
     int ret, queue_no;
 
     for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
+        if (!virtio_queue_valid(vdev, queue_no)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -695,6 +713,9 @@ static void kvm_virtio_pci_vector_mask(PCIDevice *dev, unsigned vector)
     int queue_no;
 
     for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
+        if (!virtio_queue_valid(vdev, queue_no)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -717,6 +738,9 @@ static void kvm_virtio_pci_vector_poll(PCIDevice *dev,
     VirtQueue *vq;
 
     for (queue_no = 0; queue_no < proxy->nvqs_with_notifiers; queue_no++) {
+        if (!virtio_queue_valid(vdev, queue_no)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, queue_no)) {
             break;
         }
@@ -790,6 +814,9 @@ static int virtio_pci_set_guest_notifiers(DeviceState *d, int nvqs, bool assign)
     }
 
     for (n = 0; n < nvqs; n++) {
+        if (!virtio_queue_valid(vdev, n)) {
+            continue;
+        }
         if (!virtio_queue_get_num(vdev, n)) {
             break;
         }
-- 
1.7.2.5