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vhost: fix overflow of avail entries count

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Virtio 1.0 says that the effective capacity of vrings
is equal to the virtqueue size. When avail ring was full,
we detected it as empty.

Change-Id: I72f5d45cdc14db6b934ce7780e603a3de3131594
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/396804
Tested-by: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Pawel Wodkowski <pawelx.wodkowski@intel.com>
Reviewed-by: Daniel Verkamp <daniel.verkamp@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
This commit is contained in:
Dariusz Stojaczyk 2018-01-28 10:53:03 +01:00 committed by Jim Harris
parent a78c896369
commit 808a2b05c2
1 changed files with 10 additions and 2 deletions
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12
lib/vhost/vhost.c
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@ -102,13 +102,21 @@ spdk_vhost_vq_avail_ring_get(struct spdk_vhost_virtqueue *virtqueue, uint16_t *r
struct vring_avail *avail = vring->avail;
uint16_t size_mask = vring->size - 1;
uint16_t last_idx = vring->last_avail_idx, avail_idx = avail->idx;
uint16_t count = RTE_MIN((avail_idx - last_idx) & size_mask, reqs_len);
uint16_t i;
uint16_t count, i;
count = avail_idx - last_idx;
if (spdk_likely(count == 0)) {
return 0;
}
if (spdk_unlikely(count > vring->size)) {
/* TODO: the queue is unrecoverably broken and should be marked so.
* For now we will fail silently and report there are no new avail entries.
*/
return 0;
}
count = spdk_min(count, reqs_len);
vring->last_avail_idx += count;
for (i = 0; i < count; i++) {
reqs[i] = vring->avail->ring[(last_idx + i) & size_mask];