From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52570) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cncKk-0000uO-DK for qemu-devel@nongnu.org; Mon, 13 Mar 2017 22:37:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cncKh-0006Vi-DD for qemu-devel@nongnu.org; Mon, 13 Mar 2017 22:37:10 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53434) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cncKh-0006VB-6i for qemu-devel@nongnu.org; Mon, 13 Mar 2017 22:37:07 -0400 References: <1489386583-11564-1-git-send-email-jasowang@redhat.com> <20170313105515.75981fb9.cornelia.huck@de.ibm.com> <0178911d-a930-5031-5e9f-4fdedd51fe3e@redhat.com> From: Jason Wang Message-ID: Date: Tue, 14 Mar 2017 10:37:00 +0800 MIME-Version: 1.0 In-Reply-To: <0178911d-a930-5031-5e9f-4fdedd51fe3e@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH V2 1/3] virtio: guard against NULL pfn List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini , Cornelia Huck Cc: mst@redhat.com, qemu-devel@nongnu.org On 2017=E5=B9=B403=E6=9C=8813=E6=97=A5 18:18, Paolo Bonzini wrote: > > On 13/03/2017 10:55, Cornelia Huck wrote: >> On Mon, 13 Mar 2017 14:29:41 +0800 >> Jason Wang wrote: >> >>> To avoid access stale memory region cache after reset, this patch >>> check the existence of virtqueue pfn for all exported virtqueue acces= s >>> 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; >> Shouldn't that rather return !0 (denoting a non-existing queue as >> empty)? > Yes, and the check should also go first (before the function can return= 0). > > Paolo Yes, will fix in V3. Thanks