From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50648) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cxvg4-00016U-Qg for qemu-devel@nongnu.org; Tue, 11 Apr 2017 09:17:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cxvg3-0006x0-Vz for qemu-devel@nongnu.org; Tue, 11 Apr 2017 09:17:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56954) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cxvg3-0006wi-Pw for qemu-devel@nongnu.org; Tue, 11 Apr 2017 09:17:47 -0400 From: Laurent Vivier Date: Tue, 11 Apr 2017 15:17:33 +0200 Message-Id: <20170411131733.27542-3-lvivier@redhat.com> In-Reply-To: <20170411131733.27542-1-lvivier@redhat.com> References: <20170411131733.27542-1-lvivier@redhat.com> Subject: [Qemu-devel] [PATCH 2/2] virtio-rng: stop virtqueue while the CPU is stopped List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr . David Alan Gilbert" Cc: "Michael S . Tsirkin" , Stefan Hajnoczi , Amit Shah , qemu-devel@nongnu.org If we modify the virtio-rng virqueue while the vmstate is already migrated we can have some inconsistencies between the virtqueue state and the memory content. To avoid this, stop the virtqueue while the CPU is stopped. Signed-off-by: Laurent Vivier --- hw/virtio/trace-events | 2 ++ hw/virtio/virtio-rng.c | 10 ++++++++++ 2 files changed, 12 insertions(+) diff --git a/hw/virtio/trace-events b/hw/virtio/trace-events index 6926eed..564a4b8 100644 --- a/hw/virtio/trace-events +++ b/hw/virtio/trace-events @@ -11,6 +11,8 @@ virtio_set_status(void *vdev, uint8_t val) "vdev %p val %u" # hw/virtio/virtio-rng.c virtio_rng_guest_not_ready(void *rng) "rng %p: guest not ready" +virtio_rng_cpu_is_stopped(void *rng) "rng %p: cpu is stopped" +virtio_rng_popped(void *rng) "rng %p: elem popped" virtio_rng_pushed(void *rng, size_t len) "rng %p: %zd bytes pushed" virtio_rng_request(void *rng, size_t size, unsigned quota) "rng %p: %zd bytes requested, %u bytes quota left" diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c index 9639f4e..d270d56 100644 --- a/hw/virtio/virtio-rng.c +++ b/hw/virtio/virtio-rng.c @@ -53,6 +53,15 @@ static void chr_read(void *opaque, const void *buf, size_t size) return; } + /* we can't modify the virtqueue until + * our state is fully synced + */ + + if (!runstate_check(RUN_STATE_RUNNING)) { + trace_virtio_rng_cpu_is_stopped(vrng); + return; + } + vrng->quota_remaining -= size; offset = 0; @@ -61,6 +70,7 @@ static void chr_read(void *opaque, const void *buf, size_t size) if (!elem) { break; } + trace_virtio_rng_popped(vrng); len = iov_from_buf(elem->in_sg, elem->in_num, 0, buf + offset, size - offset); offset += len; -- 2.9.3