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[Qemu-devel] [PATCH V4 1/3] virtio: guard against NULL pfn
From: |
Jason Wang |
Subject: |
[Qemu-devel] [PATCH V4 1/3] virtio: guard against NULL pfn |
Date: |
Wed, 15 Mar 2017 19:48:30 +0800 |
To avoid access stale memory region cache after reset, this patch
check the existence of virtqueue pfn for all exported virtqueue access
helpers before trying to use them.
Cc: Cornelia Huck <address@hidden>
Cc: Paolo Bonzini <address@hidden>
Reviewed-by: Cornelia Huck <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
---
Changes from V2:
- return 1 instead of 0 for virtio_queue_empty_*(), and return as
early as possible
---
hw/virtio/virtio.c | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index efce4b3..9164579 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -318,6 +318,10 @@ int virtio_queue_ready(VirtQueue *vq)
* Called within rcu_read_lock(). */
static int virtio_queue_empty_rcu(VirtQueue *vq)
{
+ if (unlikely(!vq->vring.avail)) {
+ return 1;
+ }
+
if (vq->shadow_avail_idx != vq->last_avail_idx) {
return 0;
}
@@ -329,6 +333,10 @@ int virtio_queue_empty(VirtQueue *vq)
{
bool empty;
+ if (unlikely(!vq->vring.avail)) {
+ return 1;
+ }
+
if (vq->shadow_avail_idx != vq->last_avail_idx) {
return 0;
}
@@ -431,6 +439,10 @@ void virtqueue_fill(VirtQueue *vq, const VirtQueueElement
*elem,
return;
}
+ if (unlikely(!vq->vring.used)) {
+ return;
+ }
+
idx = (idx + vq->used_idx) % vq->vring.num;
uelem.id = elem->index;
@@ -448,6 +460,10 @@ void virtqueue_flush(VirtQueue *vq, unsigned int count)
return;
}
+ if (unlikely(!vq->vring.used)) {
+ return;
+ }
+
/* Make sure buffer is written before we update index. */
smp_wmb();
trace_virtqueue_flush(vq, count);
@@ -546,6 +562,16 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int
*in_bytes,
int64_t len = 0;
int rc;
+ if (unlikely(!vq->vring.desc)) {
+ if (in_bytes) {
+ *in_bytes = 0;
+ }
+ if (out_bytes) {
+ *out_bytes = 0;
+ }
+ return;
+ }
+
rcu_read_lock();
idx = vq->last_avail_idx;
total_bufs = in_total = out_total = 0;
--
2.7.4