From 78b7d9af26ae802b3ca0d7b794b366ab4d515647 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= Date: Tue, 23 Aug 2022 20:30:27 +0200 Subject: [PATCH 12/23] vhost: use SVQ element ndescs instead of opaque data for desc validation 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: [11/21] 536ba65ff7241c4dc66362294ba8de4354260d6f (eperezmartin/qemu-kvm) Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2114060 Upstream status: git@github.com:jasowang/qemu.git net-next Since we're going to allow SVQ to add elements without the guest's knowledge and without its own VirtQueueElement, it's easier to check if an element is a valid head checking a different thing than the VirtQueueElement. Signed-off-by: Eugenio Pérez Acked-by: Jason Wang Signed-off-by: Jason Wang (cherry picked from commit 70e0841722deb363b53cdcd465af12a0d1461b60) --- hw/virtio/vhost-shadow-virtqueue.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index 2ae47d90a1..7792f3db1d 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -414,7 +414,7 @@ static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq, return NULL; } - if (unlikely(!svq->desc_state[used_elem.id].elem)) { + if (unlikely(!svq->desc_state[used_elem.id].ndescs)) { qemu_log_mask(LOG_GUEST_ERROR, "Device %s says index %u is used, but it was not available", svq->vdev->name, used_elem.id); @@ -422,6 +422,7 @@ static VirtQueueElement *vhost_svq_get_buf(VhostShadowVirtqueue *svq, } num = svq->desc_state[used_elem.id].ndescs; + svq->desc_state[used_elem.id].ndescs = 0; last_used_chain = vhost_svq_last_desc_of_chain(svq, num, used_elem.id); svq->desc_next[last_used_chain] = svq->free_head; svq->free_head = used_elem.id; -- 2.31.1