From patchwork Tue Mar 14 03:01:40 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jason Wang X-Patchwork-Id: 738539 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3vj01d5G8pz9s0g for ; Tue, 14 Mar 2017 14:03:49 +1100 (AEDT) Received: from localhost ([::1]:56120 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cnckV-0008PP-82 for incoming@patchwork.ozlabs.org; Mon, 13 Mar 2017 23:03:47 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59012) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cncie-0007QA-FP for qemu-devel@nongnu.org; Mon, 13 Mar 2017 23:01:53 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cncid-0002UT-N0 for qemu-devel@nongnu.org; Mon, 13 Mar 2017 23:01:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54874) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cncid-0002UJ-Hm for qemu-devel@nongnu.org; Mon, 13 Mar 2017 23:01:51 -0400 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9D7AB61D1A; Tue, 14 Mar 2017 03:01:51 +0000 (UTC) Received: from jason-ThinkPad-T450s.redhat.com (vpn1-6-24.pek2.redhat.com [10.72.6.24]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id v2E31kkN030343; Mon, 13 Mar 2017 23:01:49 -0400 From: Jason Wang To: mst@redhat.com, qemu-devel@nongnu.org Date: Tue, 14 Mar 2017 11:01:40 +0800 Message-Id: <1489460502-6686-2-git-send-email-jasowang@redhat.com> In-Reply-To: <1489460502-6686-1-git-send-email-jasowang@redhat.com> References: <1489460502-6686-1-git-send-email-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.68 on 10.5.11.26 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.39]); Tue, 14 Mar 2017 03:01:51 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH V3 1/3] virtio: guard against NULL pfn X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Cornelia Huck , Paolo Bonzini , Jason Wang Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" 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 Reviewed-by: Cornelia Huck --- 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;