File 0167-virtio-fix-vq-inuse-recalc-after-mi.patch of Package qemu-linux-user.4226

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File 0167-virtio-fix-vq-inuse-recalc-after-mi.patch of Package qemu-linux-user.4226

From 6bfa194e16a6b688a2e64d48e1be952df8cabfa8 Mon Sep 17 00:00:00 2001
From: Halil Pasic <pasic@linux.vnet.ibm.com>
Date: Mon, 19 Dec 2016 16:44:44 +0100
Subject: [PATCH] virtio: fix vq->inuse recalc after migr

Correct recalculation of vq->inuse after migration for the corner case
where the avail_idx has already wrapped but used_idx not yet.

Also change the type of the VirtQueue.inuse to unsigned int. This is
done to be consistent with other members representing sizes (VRing.num),
and because C99 guarantees max ring size < UINT_MAX but does not
guarantee max ring size < INT_MAX.

Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Fixes: bccdef6b ("virtio: recalculate vq->inuse after migration")
CC: qemu-stable@nongnu.org
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit e66bcc408146730958d1a840bda85d7ad51e0cd7)
[BR: BSC#1020928]
Signed-off-by: Bruce Rogers <brogers@suse.com>
---
 hw/virtio/virtio.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 411d7a4359..4738e33e1a 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -85,7 +85,7 @@ struct VirtQueue
 
     uint16_t queue_index;
 
-    int inuse;
+    unsigned int inuse;
 
     uint16_t vector;
     void (*handle_output)(VirtIODevice *vdev, VirtQueue *vq);
@@ -1112,9 +1112,11 @@ int virtio_load(VirtIODevice *vdev, QEMUFile *f, int version_id)
             /*
              * Some devices migrate VirtQueueElements that have been popped
              * from the avail ring but not yet returned to the used ring.
+             * Since max ring size < UINT16_MAX it's safe to use modulo
+             * UINT16_MAX + 1 subtraction.
              */
-            vdev->vq[i].inuse = vdev->vq[i].last_avail_idx -
-                                vdev->vq[i].used_idx;
+            vdev->vq[i].inuse = (uint16_t)(vdev->vq[i].last_avail_idx -
+                                vdev->vq[i].used_idx);
             if (vdev->vq[i].inuse > vdev->vq[i].vring.num) {
                 error_report("VQ %d size 0x%x < last_avail_idx 0x%x - "
                              "used_idx 0x%x",

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File 0167-virtio-fix-vq-inuse-recalc-after-mi.patch of Package qemu-linux-user.4226

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