[PATCH for 8.1 v2 6/6] vdpa: Cache cvq group in VhostVDPAState

["Eugenio Pérez" <eperezma@redhat.com>]

Continue the move of code that interacts with the device from control
virtqueue start to control virtqueue init.

As with previous patches, it reduces the number of ioctls in the
migration, reducing failure possibilities.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
 net/vhost-vdpa.c | 40 +++++++++++++++++++++++++++-------------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index db2c9afcb3..6a60e8cc2b 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -41,6 +41,12 @@ typedef struct VhostVDPAState {
     void *cvq_cmd_out_buffer;
     virtio_net_ctrl_ack *status;
 
+    /* CVQ group if cvq_isolated_mq */
+    uint32_t cvq_group_mq;
+
+    /* CVQ group if cvq_isolated */
+    uint32_t cvq_group;
+
     /* The device always have SVQ enabled */
     bool always_svq;
 
@@ -480,7 +486,6 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
     struct vhost_vdpa *v;
     int64_t cvq_group;
     int r;
-    Error *err = NULL;
 
     assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
 
@@ -509,18 +514,14 @@ static int vhost_vdpa_net_cvq_start(NetClientState *nc)
         if (!s->cvq_isolated_mq) {
             return 0;
         }
+
+        cvq_group = s->cvq_group_mq;
     } else {
         if (!s->cvq_isolated) {
             return 0;
         }
-    }
 
-    cvq_group = vhost_vdpa_get_vring_group(v->device_fd,
-                                           v->dev->vq_index_end - 1,
-                                           &err);
-    if (unlikely(cvq_group < 0)) {
-        error_report_err(err);
-        return cvq_group;
+        cvq_group = s->cvq_group;
     }
 
     r = vhost_vdpa_set_address_space_id(v, cvq_group, VHOST_VDPA_NET_CVQ_ASID);
@@ -790,11 +791,13 @@ static const VhostShadowVirtqueueOps vhost_vdpa_net_svq_ops = {
  * @device_fd vhost-vdpa file descriptor
  * @features features to negotiate
  * @cvq_index Control vq index
+ * @pcvq_group: Returns CVQ group if cvq is isolated.
  *
  * Returns -1 in case of error, 0 if false and 1 if true
  */
 static int vhost_vdpa_cvq_is_isolated(int device_fd, uint64_t features,
-                                      unsigned cvq_index, Error **errp)
+                                      unsigned cvq_index, uint32_t *pcvq_group,
+                                      Error **errp)
 {
     int64_t cvq_group;
     int r;
@@ -810,6 +813,7 @@ static int vhost_vdpa_cvq_is_isolated(int device_fd, uint64_t features,
         return cvq_group;
     }
 
+    *pcvq_group = (uint32_t)cvq_group;
     for (int i = 0; i < cvq_index; ++i) {
         int64_t group = vhost_vdpa_get_vring_group(device_fd, i, errp);
 
@@ -836,12 +840,15 @@ static int vhost_vdpa_cvq_is_isolated(int device_fd, uint64_t features,
  *                    negotiated.
  * @cvq_isolated_mq   It'll be set to true if cvq is isolated if mq is
  *                    negotiated.
+ * @cvq_group         CVQ group if MQ is not negotiated.
+ * @cvq_group_mq      CVQ group if MQ is negotiated.
  *
  * Returns -1 in case of failure
  */
 static int vhost_vdpa_probe_cvq_isolation(int device_fd, uint64_t features,
                                           int cvq_index, bool *cvq_isolated,
-                                          bool *cvq_isolated_mq, Error **errp)
+                                          bool *cvq_isolated_mq, uint32_t *cvq_group,
+                                          uint32_t *cvq_group_mq, Error **errp)
 {
     uint64_t backend_features;
     int r;
@@ -850,6 +857,8 @@ static int vhost_vdpa_probe_cvq_isolation(int device_fd, uint64_t features,
 
     *cvq_isolated = false;
     *cvq_isolated_mq = false;
+    *cvq_group = 0;
+    *cvq_group_mq = 0;
     r = ioctl(device_fd, VHOST_GET_BACKEND_FEATURES, &backend_features);
     if (unlikely(r < 0)) {
         error_setg_errno(errp, errno, "Cannot get vdpa backend_features");
@@ -862,7 +871,7 @@ static int vhost_vdpa_probe_cvq_isolation(int device_fd, uint64_t features,
 
     r = vhost_vdpa_cvq_is_isolated(device_fd,
                                    features & ~BIT_ULL(VIRTIO_NET_F_MQ), 2,
-                                   errp);
+                                   cvq_group, errp);
     if (unlikely(r < 0)) {
         if (r == -ENOTSUP) {
             /*
@@ -884,7 +893,8 @@ static int vhost_vdpa_probe_cvq_isolation(int device_fd, uint64_t features,
         return 0;
     }
 
-    r = vhost_vdpa_cvq_is_isolated(device_fd, features, cvq_index * 2, errp);
+    r = vhost_vdpa_cvq_is_isolated(device_fd, features, cvq_index * 2,
+                                   cvq_group_mq, errp);
     if (unlikely(r < 0)) {
         return r;
     }
@@ -911,6 +921,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
     int ret = 0;
     assert(name);
     bool cvq_isolated, cvq_isolated_mq;
+    uint32_t cvq_group, cvq_group_mq;
 
     if (is_datapath) {
         nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device,
@@ -918,7 +929,8 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
     } else {
         ret = vhost_vdpa_probe_cvq_isolation(vdpa_device_fd, features,
                                              queue_pair_index, &cvq_isolated,
-                                             &cvq_isolated_mq, errp);
+                                             &cvq_isolated_mq, &cvq_group,
+                                             &cvq_group_mq, errp);
         if (unlikely(ret)) {
             return NULL;
         }
@@ -951,6 +963,8 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
         s->vhost_vdpa.shadow_vq_ops_opaque = s;
         s->cvq_isolated = cvq_isolated;
         s->cvq_isolated_mq = cvq_isolated_mq;
+        s->cvq_group = cvq_group;
+        s->cvq_group_mq = cvq_group_mq;
 
         /*
          * TODO: We cannot migrate devices with CVQ as there is no way to set
-- 
2.31.1