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virtio_mmio: fix off by one error allocating queue 

vm_setup_vq fails to allow VirtQueues needing only 2 pages of
storage, as it should. Found with a kernel using 64kB pages, but
can be provoked if a virtio device reports QueueNumMax where the
descriptor table and available ring fit in one page, and the used
ring on the second (<= 227 descriptors with 4kB pages and <= 3640
with 64kB pages.)

Signed-off-by: Brian Foley <brian.foley@arm.com>
Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Brian Foley 2012-09-24 14:33:41 +01:00 committed by Rusty Russell
parent 74a74b376c
commit 3850d29fc4
1 changed files with 2 additions and 2 deletions
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4
drivers/virtio/virtio_mmio.c
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@ -334,8 +334,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
while (1) {
size = PAGE_ALIGN(vring_size(info->num,
VIRTIO_MMIO_VRING_ALIGN));
/* Already smallest possible allocation? */
if (size <= VIRTIO_MMIO_VRING_ALIGN * 2) {
/* Did the last iter shrink the queue below minimum size? */
if (size < VIRTIO_MMIO_VRING_ALIGN * 2) {
err = -ENOMEM;
goto error_alloc_pages;
}