From 3f2ba7cce6b272a8b5c8953e8923e799e4aa7b88 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= Date: Mon, 18 Jul 2022 14:05:45 +0200 Subject: [PATCH 02/23] vhost: Get vring base from vq, not svq MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Eugenio Pérez RH-MergeRequest: 116: vdpa: Restore device state on destination RH-Bugzilla: 2114060 RH-Acked-by: Cindy Lu RH-Acked-by: Miroslav Rezanina RH-Commit: [1/21] e7e0294bbc98f69ccdbc4af4715857e77b017f80 (eperezmartin/qemu-kvm) Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2114060 Upstream status: Merged The SVQ vring used idx usually match with the guest visible one, as long as all the guest buffers (GPA) maps to exactly one buffer within qemu's VA. However, as we can see in virtqueue_map_desc, a single guest buffer could map to many buffers in SVQ vring. Also, its also a mistake to rewind them at the source of migration. Since VirtQueue is able to migrate the inflight descriptors, its responsability of the destination to perform the rewind just in case it cannot report the inflight descriptors to the device. This makes easier to migrate between backends or to recover them in vhost devices that support set in flight descriptors. Fixes: 6d0b22266633 ("vdpa: Adapt vhost_vdpa_get_vring_base to SVQ") Signed-off-by: Eugenio Pérez Signed-off-by: Jason Wang (cherry picked from commit 2fdac348fd3d243bb964937236af3cc27ae7af2b) --- hw/virtio/vhost-vdpa.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c index 03dc6014b0..96334ab5b6 100644 --- a/hw/virtio/vhost-vdpa.c +++ b/hw/virtio/vhost-vdpa.c @@ -1177,7 +1177,18 @@ static int vhost_vdpa_set_vring_base(struct vhost_dev *dev, struct vhost_vring_state *ring) { struct vhost_vdpa *v = dev->opaque; + VirtQueue *vq = virtio_get_queue(dev->vdev, ring->index); + /* + * vhost-vdpa devices does not support in-flight requests. Set all of them + * as available. + * + * TODO: This is ok for networking, but other kinds of devices might + * have problems with these retransmissions. + */ + while (virtqueue_rewind(vq, 1)) { + continue; + } if (v->shadow_vqs_enabled) { /* * Device vring base was set at device start. SVQ base is handled by @@ -1193,21 +1204,10 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev *dev, struct vhost_vring_state *ring) { struct vhost_vdpa *v = dev->opaque; - int vdpa_idx = ring->index - dev->vq_index; int ret; if (v->shadow_vqs_enabled) { - VhostShadowVirtqueue *svq = g_ptr_array_index(v->shadow_vqs, vdpa_idx); - - /* - * Setting base as last used idx, so destination will see as available - * all the entries that the device did not use, including the in-flight - * processing ones. - * - * TODO: This is ok for networking, but other kinds of devices might - * have problems with these retransmissions. - */ - ring->num = svq->last_used_idx; + ring->num = virtio_queue_get_last_avail_idx(dev->vdev, ring->index); return 0; } -- 2.31.1