From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45140) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YhJNX-0001PI-F8 for qemu-devel@nongnu.org; Sun, 12 Apr 2015 11:00:56 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YhJNU-00089M-8p for qemu-devel@nongnu.org; Sun, 12 Apr 2015 11:00:55 -0400 Received: from mx1.redhat.com ([209.132.183.28]:50490) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YhJNU-00088z-3b for qemu-devel@nongnu.org; Sun, 12 Apr 2015 11:00:52 -0400 Date: Sun, 12 Apr 2015 17:00:48 +0200 From: "Michael S. Tsirkin" Message-ID: <1428849904-28953-2-git-send-email-mst@redhat.com> References: <1428849904-28953-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1428849904-28953-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH 2/2] virtio-balloon: virtio 1 support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Cornelia Huck , Rusty Russell , Anthony Liguori , virtualization@lists.linux-foundation.org Virtio 1.0 doesn't include a modern balloon device. At some point we'll likely define an incompatible interface with a different ID and different semantics. But for now, it's not a big effort to support a transitional balloon device: this has the advantage of supporting existing drivers, transparently, as well as transports that don't allow mixing virtio 0 and virtio 1 devices. And balloon is an easy device to test, so it's also useful for people to test virtio core handling of transitional devices. The only interface issue is with the stats buffer, which has misaligned fields. We could leave it as is, but this sets a bad precedent that others might copy by mistake. Signed-off-by: Michael S. Tsirkin --- hw/virtio/virtio-balloon.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c index d2d7c3e..568a008 100644 --- a/hw/virtio/virtio-balloon.c +++ b/hw/virtio/virtio-balloon.c @@ -239,7 +239,8 @@ static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) { VirtIOBalloon *s = VIRTIO_BALLOON(vdev); VirtQueueElement *elem = &s->stats_vq_elem; - VirtIOBalloonStat stat; + VirtIOBalloonStat legacy_stat; + VirtIOBalloonStatModern modern_stat; size_t offset = 0; qemu_timeval tv; @@ -253,14 +254,28 @@ static void virtio_balloon_receive_stats(VirtIODevice *vdev, VirtQueue *vq) */ reset_stats(s); - while (iov_to_buf(elem->out_sg, elem->out_num, offset, &stat, sizeof(stat)) - == sizeof(stat)) { - uint16_t tag = virtio_tswap16(vdev, stat.tag); - uint64_t val = virtio_tswap64(vdev, stat.val); + if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) { + while (iov_to_buf(elem->out_sg, elem->out_num, offset, + &modern_stat, sizeof(modern_stat)) + == sizeof(modern_stat)) { + uint16_t tag = le16_to_cpu(modern_stat.tag); + uint64_t val = le64_to_cpu(modern_stat.val); - offset += sizeof(stat); - if (tag < VIRTIO_BALLOON_S_NR) - s->stats[tag] = val; + offset += sizeof(modern_stat); + if (tag < VIRTIO_BALLOON_S_NR) + s->stats[tag] = val; + } + } else { + while (iov_to_buf(elem->out_sg, elem->out_num, offset, + &legacy_stat, sizeof(legacy_stat)) + == sizeof(legacy_stat)) { + uint16_t tag = virtio_tswap16(vdev, legacy_stat.tag); + uint64_t val = virtio_tswap64(vdev, legacy_stat.val); + + offset += sizeof(legacy_stat); + if (tag < VIRTIO_BALLOON_S_NR) + s->stats[tag] = val; + } } s->stats_vq_offset = offset; -- MST