From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753418AbbC3RhX (ORCPT ); Mon, 30 Mar 2015 13:37:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45907 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753374AbbC3RhU (ORCPT ); Mon, 30 Mar 2015 13:37:20 -0400 Date: Mon, 30 Mar 2015 19:37:12 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: virtio-dev@lists.oasis-open.org, virtualization@lists.linux-foundation.org, Rusty Russell , linux-api@vger.kernel.org Subject: [PATCH 1/6] virtio_balloon: transitional interface Message-ID: <1427737006-23191-2-git-send-email-mst@redhat.com> References: <1427737006-23191-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1427737006-23191-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Virtio 1.0 doesn't include a modern balloon device. But it's not a big change to support a transitional balloon device: this has the advantage of supporting existing drivers, transparently. Signed-off-by: Michael S. Tsirkin --- include/uapi/linux/virtio_balloon.h | 6 ++++++ drivers/virtio/virtio_balloon.c | 8 ++++++-- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h index 4b0488f..5d83902 100644 --- a/include/uapi/linux/virtio_balloon.h +++ b/include/uapi/linux/virtio_balloon.h @@ -56,4 +56,10 @@ struct virtio_balloon_stat { __u64 val; } __attribute__((packed)); +struct virtio_balloon_stat_modern { + __u8 reserved[6]; + __u16 tag; + __u64 val; +}; + #endif /* _LINUX_VIRTIO_BALLOON_H */ diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index 6a356e3..68e937f 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -77,7 +77,7 @@ struct virtio_balloon { /* Memory statistics */ int need_stats_update; - struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; + struct virtio_balloon_stat_modern stats[VIRTIO_BALLOON_S_NR]; /* To register callback in oom notifier call chain */ struct notifier_block nb; @@ -269,7 +269,11 @@ static void stats_handle_request(struct virtio_balloon *vb) vq = vb->stats_vq; if (!virtqueue_get_buf(vq, &len)) return; - sg_init_one(&sg, vb->stats, sizeof(vb->stats)); + if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) + sg_init_one(&sg, vb->stats, sizeof(vb->stats)); + else + sg_init_one(&sg, &vb->stats->tag, sizeof(vb->stats) - + offsetof(typeof(*vb->stats, tag); virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); virtqueue_kick(vq); } -- MST