From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: [PATCH] virtio_balloon: Notify guest only after deflating the balloon Date: Sat, 2 Jul 2011 06:06:56 +0300 Message-ID: <1309576016-22800-1-git-send-email-levinsasha928@gmail.com> Cc: Sasha Levin , Rusty Russell , "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org To: linux-kernel@vger.kernel.org Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:62047 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751833Ab1GBDIa (ORCPT ); Fri, 1 Jul 2011 23:08:30 -0400 Sender: kvm-owner@vger.kernel.org List-ID: Unless the host requires that requested pages won't be used until he us notified (VIRTIO_BALLOON_F_MUST_TELL_HOST), only notify after deflating the balloon. This will avoid having to take an exit before actually using the pages. Cc: Rusty Russell Cc: "Michael S. Tsirkin" Cc: virtualization@lists.linux-foundation.org Cc: kvm@vger.kernel.org Signed-off-by: Sasha Levin --- drivers/virtio/virtio_balloon.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c index e058ace..055f95d 100644 --- a/drivers/virtio/virtio_balloon.c +++ b/drivers/virtio/virtio_balloon.c @@ -148,14 +148,18 @@ static void leak_balloon(struct virtio_balloon *vb, size_t num) vb->num_pages--; } - /* - * Note that if - * virtio_has_feature(vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST); - * is true, we *have* to do it in this order + * If the host doesn't require us to notify him before using + * pages which belong to the balloon, update him only after + * freeing those pages for guest use. */ - tell_host(vb, vb->deflate_vq); - release_pages_by_pfn(vb->pfns, vb->num_pfns); + if (virtio_has_feature(vb->vdev, VIRTIO_BALLOON_F_MUST_TELL_HOST)) { + tell_host(vb, vb->deflate_vq); + release_pages_by_pfn(vb->pfns, vb->num_pfns); + } else { + release_pages_by_pfn(vb->pfns, vb->num_pfns); + tell_host(vb, vb->deflate_vq); + } } static inline void update_stat(struct virtio_balloon *vb, int idx, -- 1.7.6