From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54734) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cnJUS-0008Nw-Tj for qemu-devel@nongnu.org; Mon, 13 Mar 2017 02:29:57 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cnJUP-00023D-Nw for qemu-devel@nongnu.org; Mon, 13 Mar 2017 02:29:56 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36246) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cnJUP-00022W-Hx for qemu-devel@nongnu.org; Mon, 13 Mar 2017 02:29:53 -0400 From: Jason Wang Date: Mon, 13 Mar 2017 14:29:41 +0800 Message-Id: <1489386583-11564-1-git-send-email-jasowang@redhat.com> Subject: [Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mst@redhat.com, qemu-devel@nongnu.org Cc: Jason Wang , Cornelia Huck , Paolo Bonzini 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 Cc: Paolo Bonzini Signed-off-by: Jason Wang --- hw/virtio/virtio.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index efce4b3..76cc81b 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -322,6 +322,10 @@ static int virtio_queue_empty_rcu(VirtQueue *vq) return 0; } + if (unlikely(!vq->vring.avail)) { + return 0; + } + return vring_avail_idx(vq) == vq->last_avail_idx; } @@ -333,6 +337,10 @@ int virtio_queue_empty(VirtQueue *vq) return 0; } + if (unlikely(!vq->vring.avail)) { + return 0; + } + rcu_read_lock(); empty = vring_avail_idx(vq) == vq->last_avail_idx; rcu_read_unlock(); @@ -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 +562,11 @@ void virtqueue_get_avail_bytes(VirtQueue *vq, unsigned int *in_bytes, int64_t len = 0; int rc; + if (unlikely(!vq->vring.desc)) { + *in_bytes = *out_bytes = 0; + return; + } + rcu_read_lock(); idx = vq->last_avail_idx; total_bufs = in_total = out_total = 0; -- 2.7.4