[PATCH 18/18] vhost-vdpa: multiqueue support

[Jason Wang <jasowang@redhat.com>]

This patch implements the multiqueue support for vhost-vdpa. This is
done simply by reading the number of queue pairs from the config space
and initialize the datapath and control path net client.

Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 hw/net/virtio-net.c |  3 +-
 net/vhost-vdpa.c    | 98 ++++++++++++++++++++++++++++++++++++++++-----
 2 files changed, 91 insertions(+), 10 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 5074b521cf..2c2ed98c0b 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -3370,7 +3370,8 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     n->max_ncs = MAX(n->nic_conf.peers.queues, 1);
 
-    /* Figure out the datapath queue pairs since the bakcend could
+    /*
+     * Figure out the datapath queue pairs since the bakcend could
      * provide control queue via peers as well.
      */
     if (n->nic_conf.peers.queues) {
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index cc11b2ec40..048344b4bc 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -18,6 +18,7 @@
 #include "qemu/error-report.h"
 #include "qemu/option.h"
 #include "qapi/error.h"
+#include <linux/vhost.h>
 #include <sys/ioctl.h>
 #include <err.h>
 #include "standard-headers/linux/virtio_net.h"
@@ -52,6 +53,8 @@ const int vdpa_feature_bits[] = {
     VIRTIO_NET_F_HOST_UFO,
     VIRTIO_NET_F_MRG_RXBUF,
     VIRTIO_NET_F_MTU,
+    VIRTIO_NET_F_MQ,
+    VIRTIO_NET_F_CTRL_VQ,
     VIRTIO_F_IOMMU_PLATFORM,
     VIRTIO_F_RING_PACKED,
     VIRTIO_NET_F_RSS,
@@ -82,7 +85,8 @@ static int vhost_vdpa_net_check_device_id(struct vhost_net *net)
     return ret;
 }
 
-static int vhost_vdpa_add(NetClientState *ncs, void *be)
+static int vhost_vdpa_add(NetClientState *ncs, void *be, int qp_index,
+                          int nvqs)
 {
     VhostNetOptions options;
     struct vhost_net *net = NULL;
@@ -95,7 +99,7 @@ static int vhost_vdpa_add(NetClientState *ncs, void *be)
     options.net_backend = ncs;
     options.opaque      = be;
     options.busyloop_timeout = 0;
-    options.nvqs = 2;
+    options.nvqs = nvqs;
 
     net = vhost_net_init(&options);
     if (!net) {
@@ -159,18 +163,28 @@ static NetClientInfo net_vhost_vdpa_info = {
 static NetClientState *net_vhost_vdpa_init(NetClientState *peer,
                                            const char *device,
                                            const char *name,
-                                           int vdpa_device_fd)
+                                           int vdpa_device_fd,
+                                           int qp_index,
+                                           int nvqs,
+                                           bool is_datapath)
 {
     NetClientState *nc = NULL;
     VhostVDPAState *s;
     int ret = 0;
     assert(name);
-    nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device, name);
+    if (is_datapath) {
+        nc = qemu_new_net_client(&net_vhost_vdpa_info, peer, device,
+                                 name);
+    } else {
+        nc = qemu_new_net_control_client(&net_vhost_vdpa_info, peer,
+                                         device, name);
+    }
     snprintf(nc->info_str, sizeof(nc->info_str), TYPE_VHOST_VDPA);
     s = DO_UPCAST(VhostVDPAState, nc, nc);
 
     s->vhost_vdpa.device_fd = vdpa_device_fd;
-    ret = vhost_vdpa_add(nc, (void *)&s->vhost_vdpa);
+    s->vhost_vdpa.index = qp_index;
+    ret = vhost_vdpa_add(nc, (void *)&s->vhost_vdpa, qp_index, nvqs);
     if (ret) {
         qemu_del_net_client(nc);
         return NULL;
@@ -196,12 +210,52 @@ static int net_vhost_check_net(void *opaque, QemuOpts *opts, Error **errp)
     return 0;
 }
 
+static int vhost_vdpa_get_max_qps(int fd, int *has_cvq, Error **errp)
+{
+    unsigned long config_size = offsetof(struct vhost_vdpa_config, buf);
+    struct vhost_vdpa_config *config;
+    __virtio16 *max_qps;
+    uint64_t features;
+    int ret;
+
+    ret = ioctl(fd, VHOST_GET_FEATURES, &features);
+    if (ret) {
+        error_setg(errp, "Fail to query features from vhost-vDPA device");
+        return ret;
+    }
+
+    if (features & (1 << VIRTIO_NET_F_CTRL_VQ)) {
+        *has_cvq = 1;
+    } else {
+        *has_cvq = 0;
+    }
+
+    if (features & (1 << VIRTIO_NET_F_MQ)) {
+        config = g_malloc0(config_size + sizeof(*max_qps));
+        config->off = offsetof(struct virtio_net_config, max_virtqueue_pairs);
+        config->len = sizeof(*max_qps);
+
+        ret = ioctl(fd, VHOST_VDPA_GET_CONFIG, config);
+        if (ret) {
+            error_setg(errp, "Fail to get config from vhost-vDPA device");
+            return -ret;
+        }
+
+        max_qps = (__virtio16 *)&config->buf;
+
+        return lduw_le_p(max_qps);
+    }
+
+    return 1;
+}
+
 int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
                         NetClientState *peer, Error **errp)
 {
     const NetdevVhostVDPAOptions *opts;
     int vdpa_device_fd;
-    NetClientState *nc;
+    NetClientState **ncs, *nc;
+    int qps, i, has_cvq = 0;
 
     assert(netdev->type == NET_CLIENT_DRIVER_VHOST_VDPA);
     opts = &netdev->u.vhost_vdpa;
@@ -216,11 +270,37 @@ int net_init_vhost_vdpa(const Netdev *netdev, const char *name,
         return -errno;
     }
 
-    nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name, vdpa_device_fd);
-    if (!nc) {
+    qps = vhost_vdpa_get_max_qps(vdpa_device_fd, &has_cvq, errp);
+    if (qps < 0) {
         qemu_close(vdpa_device_fd);
-        return -1;
+        return qps;
+    }
+
+    ncs = g_malloc0(sizeof(*ncs) * qps);
+
+    for (i = 0; i < qps; i++) {
+        ncs[i] = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
+                                     vdpa_device_fd, i, 2, true);
+        if (!ncs[i])
+            goto err;
     }
 
+    if (has_cvq) {
+        nc = net_vhost_vdpa_init(peer, TYPE_VHOST_VDPA, name,
+                                 vdpa_device_fd, i, 1, false);
+        if (!nc)
+            goto err;
+    }
+
+    g_free(ncs);
     return 0;
+
+err:
+    if (i) {
+        qemu_del_net_client(ncs[0]);
+    }
+    qemu_close(vdpa_device_fd);
+    g_free(ncs);
+
+    return -1;
 }
-- 
2.25.1