[PATCH v4 6/6] vdpa: Always start CVQ in SVQ mode

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

Isolate control virtqueue in its own group, allowing to intercept control
commands but letting dataplane run totally passthrough to the guest.

Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
---
v4:
* Squash vhost_vdpa_cvq_group_is_independent.
* Rebased on last CVQ start series, that allocated CVQ cmd bufs at load
* Do not check for cvq index on vhost_vdpa_net_prepare, we only have one
  that callback registered in that NetClientInfo.

v3:
* Make asid related queries print a warning instead of returning an
  error and stop the start of qemu.
---
 hw/virtio/vhost-vdpa.c |   3 +-
 net/vhost-vdpa.c       | 124 +++++++++++++++++++++++++++++++++++++++--
 2 files changed, 122 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index 3eb67b27b7..69f34f4cc5 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -678,7 +678,8 @@ static int vhost_vdpa_set_backend_cap(struct vhost_dev *dev)
 {
     uint64_t features;
     uint64_t f = 0x1ULL << VHOST_BACKEND_F_IOTLB_MSG_V2 |
-        0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH;
+        0x1ULL << VHOST_BACKEND_F_IOTLB_BATCH |
+        0x1ULL << VHOST_BACKEND_F_IOTLB_ASID;
     int r;
 
     if (vhost_vdpa_call(dev, VHOST_GET_BACKEND_FEATURES, &features)) {
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index bf78b1332f..c820a5fd9f 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -37,6 +37,9 @@ typedef struct VhostVDPAState {
     /* Control commands shadow buffers */
     void *cvq_cmd_out_buffer, *cvq_cmd_in_buffer;
 
+    /* Number of address spaces supported by the device */
+    unsigned address_space_num;
+
     /* The device always have SVQ enabled */
     bool always_svq;
     bool started;
@@ -100,6 +103,9 @@ static const uint64_t vdpa_svq_device_features =
     BIT_ULL(VIRTIO_NET_F_RSC_EXT) |
     BIT_ULL(VIRTIO_NET_F_STANDBY);
 
+#define VHOST_VDPA_NET_CVQ_PASSTHROUGH 0
+#define VHOST_VDPA_NET_CVQ_ASID 1
+
 VHostNetState *vhost_vdpa_get_vhost_net(NetClientState *nc)
 {
     VhostVDPAState *s = DO_UPCAST(VhostVDPAState, nc, nc);
@@ -224,6 +230,37 @@ static NetClientInfo net_vhost_vdpa_info = {
         .check_peer_type = vhost_vdpa_check_peer_type,
 };
 
+static void vhost_vdpa_get_vring_group(int device_fd,
+                                       struct vhost_vring_state *state)
+{
+    int r = ioctl(device_fd, VHOST_VDPA_GET_VRING_GROUP, state);
+    if (unlikely(r < 0)) {
+        /*
+         * Assume all groups are 0, the consequences are the same and we will
+         * not abort device creation
+         */
+        state->num = 0;
+    }
+}
+
+static int vhost_vdpa_set_address_space_id(struct vhost_vdpa *v,
+                                           unsigned vq_group,
+                                           unsigned asid_num)
+{
+    struct vhost_vring_state asid = {
+        .index = vq_group,
+        .num = asid_num,
+    };
+    int ret;
+
+    ret = ioctl(v->device_fd, VHOST_VDPA_SET_GROUP_ASID, &asid);
+    if (unlikely(ret < 0)) {
+        warn_report("Can't set vq group %u asid %u, errno=%d (%s)",
+            asid.index, asid.num, errno, g_strerror(errno));
+    }
+    return ret;
+}
+
 static void vhost_vdpa_cvq_unmap_buf(struct vhost_vdpa *v, void *addr)
 {
     VhostIOVATree *tree = v->iova_tree;
@@ -298,11 +335,55 @@ dma_map_err:
 static int vhost_vdpa_net_cvq_prepare(NetClientState *nc)
 {
     VhostVDPAState *s;
+    struct vhost_vdpa *v;
+    struct vhost_vring_state cvq_group = {};
     int r;
 
     assert(nc->info->type == NET_CLIENT_DRIVER_VHOST_VDPA);
 
     s = DO_UPCAST(VhostVDPAState, nc, nc);
+    v = &s->vhost_vdpa;
+    cvq_group.index = v->dev->vq_index_end - 1;
+
+    /* Default values */
+    v->shadow_vqs_enabled = false;
+    s->vhost_vdpa.address_space_id = VHOST_VDPA_NET_CVQ_PASSTHROUGH;
+
+    if (s->always_svq) {
+        v->shadow_vqs_enabled = true;
+        goto out;
+    }
+
+    if (s->address_space_num < 2) {
+        return 0;
+    }
+
+    /**
+     * Check if all the virtqueues of the virtio device are in a different vq
+     * than the last vq. VQ group of last group passed in cvq_group.
+     */
+    vhost_vdpa_get_vring_group(v->device_fd, &cvq_group);
+    for (int i = 0; i < (v->dev->vq_index_end - 1); ++i) {
+        struct vhost_vring_state vq_group = {
+            .index = i,
+        };
+
+        vhost_vdpa_get_vring_group(v->device_fd, &vq_group);
+        if (unlikely(vq_group.num == cvq_group.num)) {
+            warn_report("CVQ %u group is the same as VQ %u one (%u)",
+                         cvq_group.index, vq_group.index, cvq_group.num);
+            return 0;
+        }
+    }
+
+    r = vhost_vdpa_set_address_space_id(v, cvq_group.num,
+                                        VHOST_VDPA_NET_CVQ_ASID);
+    if (r == 0) {
+        v->shadow_vqs_enabled = true;
+        s->vhost_vdpa.address_space_id = VHOST_VDPA_NET_CVQ_ASID;
+    }
+
+out:
     if (!s->vhost_vdpa.shadow_vqs_enabled) {
         return 0;
     }
@@ -523,12 +604,38 @@ static const VhostShadowVirtqueueOps vhost_vdpa_net_svq_ops = {
     .avail_handler = vhost_vdpa_net_handle_ctrl_avail,
 };
 
+static uint32_t vhost_vdpa_get_as_num(int vdpa_device_fd)
+{
+    uint64_t features;
+    unsigned num_as;
+    int r;
+
+    r = ioctl(vdpa_device_fd, VHOST_GET_BACKEND_FEATURES, &features);
+    if (unlikely(r < 0)) {
+        warn_report("Cannot get backend features");
+        return 1;
+    }
+
+    if (!(features & BIT_ULL(VHOST_BACKEND_F_IOTLB_ASID))) {
+        return 1;
+    }
+
+    r = ioctl(vdpa_device_fd, VHOST_VDPA_GET_AS_NUM, &num_as);
+    if (unlikely(r < 0)) {
+        warn_report("Cannot retrieve number of supported ASs");
+        return 1;
+    }
+
+    return num_as;
+}
+
 static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
                                            const char *device,
                                            const char *name,
                                            int vdpa_device_fd,
                                            int queue_pair_index,
                                            int nvqs,
+                                           unsigned nas,
                                            bool is_datapath,
                                            bool svq,
                                            VhostIOVATree *iova_tree)
@@ -547,6 +654,7 @@ static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
     snprintf(nc->info_str, sizeof(nc->info_str), TYPE_VHOST_VDPA);
     s = DO_UPCAST(VhostVDPAState, nc, nc);
 
+    s->address_space_num = nas;
     s->vhost_vdpa.device_fd = vdpa_device_fd;
     s->vhost_vdpa.index = queue_pair_index;
     s->always_svq = svq;
@@ -632,6 +740,8 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
     g_autoptr(VhostIOVATree) iova_tree = NULL;
     NetClientState *nc;
     int queue_pairs, r, i = 0, has_cvq = 0;
+    unsigned num_as = 1;
+    bool svq_cvq;
 
     assert(netdev->type == NET_CLIENT_DRIVER_VHOST_VDPA);
     opts = &netdev->u.vhost_vdpa;
@@ -656,7 +766,13 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
         goto err;
     }
 
-    if (opts->x_svq) {
+    svq_cvq = opts->x_svq;
+    if (has_cvq && !opts->x_svq) {
+        num_as = vhost_vdpa_get_as_num(vdpa_device_fd);
+        svq_cvq = num_as > 1;
+    }
+
+    if (opts->x_svq || svq_cvq) {
         struct vhost_vdpa_iova_range iova_range;
 
         uint64_t invalid_dev_features =
@@ -679,15 +795,15 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
 
     for (i = 0; i < queue_pairs; i++) {
         ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
-                                     vdpa_device_fd, i, 2, true, opts->x_svq,
-                                     iova_tree);
+                                     vdpa_device_fd, i, 2, num_as, true,
+                                     opts->x_svq, iova_tree);
         if (!ncs[i])
             goto err;
     }
 
     if (has_cvq) {
         nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
-                                 vdpa_device_fd, i, 1, false,
+                                 vdpa_device_fd, i, 1, num_as, false,
                                  opts->x_svq, iova_tree);
         if (!nc)
             goto err;
-- 
2.31.1