From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39173) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1eFPE4-00084B-9n for qemu-devel@nongnu.org; Thu, 16 Nov 2017 13:49:25 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1eFPE1-0000ig-7k for qemu-devel@nongnu.org; Thu, 16 Nov 2017 13:49:24 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60612) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1eFPE1-0000hR-1e for qemu-devel@nongnu.org; Thu, 16 Nov 2017 13:49:21 -0500 From: Maxime Coquelin Date: Thu, 16 Nov 2017 19:48:34 +0100 Message-Id: <20171116184835.28556-2-maxime.coquelin@redhat.com> In-Reply-To: <20171116184835.28556-1-maxime.coquelin@redhat.com> References: <20171116184835.28556-1-maxime.coquelin@redhat.com> Subject: [Qemu-devel] [PATCH 1/2] virtio: Add queue interface to restore avail index from vring used index List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: mst@redhat.com, yuri.benditovich@daynix.com, yvugenfi@redhat.com, jasowang@redhat.com, qemu-devel@nongnu.org Cc: Maxime Coquelin In case of backend crash, it is not possible to restore internal avail index from the backend value as vhost_get_vring_base callback fails. This patch provides a new interface to restore internal avail index from the vring used index, as done by some vhost-user backend on reconnection. Signed-off-by: Maxime Coquelin --- hw/virtio/virtio.c | 10 ++++++++++ include/hw/virtio/virtio.h | 1 + 2 files changed, 11 insertions(+) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 5884ce3480..583516c428 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -2310,6 +2310,16 @@ void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx) vdev->vq[n].shadow_avail_idx = idx; } +void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n) +{ + rcu_read_lock(); + if (vdev->vq[n].vring.desc) { + vdev->vq[n].last_avail_idx = vring_used_idx(&vdev->vq[n]); + vdev->vq[n].shadow_avail_idx = vdev->vq[n].last_avail_idx; + } + rcu_read_unlock(); +} + void virtio_queue_update_used_idx(VirtIODevice *vdev, int n) { rcu_read_lock(); diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h index 5abada6966..098bdaaea3 100644 --- a/include/hw/virtio/virtio.h +++ b/include/hw/virtio/virtio.h @@ -272,6 +272,7 @@ hwaddr virtio_queue_get_avail_size(VirtIODevice *vdev, int n); hwaddr virtio_queue_get_used_size(VirtIODevice *vdev, int n); uint16_t virtio_queue_get_last_avail_idx(VirtIODevice *vdev, int n); void virtio_queue_set_last_avail_idx(VirtIODevice *vdev, int n, uint16_t idx); +void virtio_queue_restore_last_avail_idx(VirtIODevice *vdev, int n); void virtio_queue_invalidate_signalled_used(VirtIODevice *vdev, int n); void virtio_queue_update_used_idx(VirtIODevice *vdev, int n); VirtQueue *virtio_get_queue(VirtIODevice *vdev, int n); -- 2.14.3