From: Eugenio Pérez <eperezma@redhat.com>

This allows vhost_vdpa to track if it is safe to get the vring base from
the device or not.  If it is not, vhost can fall back to fetch idx from
the guest buffer again.

No functional change intended in this patch, later patches will use this
field.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
Message-Id: <20230303172445.1089785-6-eperezma@redhat.com>
Tested-by: Lei Yang <leiyang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/virtio/vhost-vdpa.h | 2 ++
 hw/virtio/vhost-vdpa.c         | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index 7997f09a8d..4a7d396674 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -42,6 +42,8 @@ typedef struct vhost_vdpa {
     bool shadow_vqs_enabled;
     /* Vdpa must send shadow addresses as IOTLB key for data queues, not GPA */
     bool shadow_data;
+    /* Device suspended successfully */
+    bool suspended;
     /* IOVA mapping used by the Shadow Virtqueue */
     VhostIOVATree *iova_tree;
     GPtrArray *shadow_vqs;
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 1550b1e26a..517e3cdc8d 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -1193,6 +1193,14 @@ static int vhost_vdpa_get_vring_base(struct vhost_dev *dev,
         return 0;
     }
 
+    if (!v->suspended) {
+        /*
+         * Cannot trust in value returned by device, let vhost recover used
+         * idx from guest.
+         */
+        return -1;
+    }
+
     ret = vhost_vdpa_call(dev, VHOST_GET_VRING_BASE, ring);
     trace_vhost_vdpa_get_vring_base(dev, ring->index, ring->num);
     return ret;
-- 
MST