[PATCH 3/5] virtio-net: add RSS support for Vhost backends

[Maxime Coquelin]

This patch introduces new Vhost backend callbacks to
support RSS, and makes them called in Virtio-net
device.

It will be used by Vhost-user backend implementation to
support RSS feature.

Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
---
 hw/net/vhost_net-stub.c           | 10 ++++++
 hw/net/vhost_net.c                | 22 +++++++++++++
 hw/net/virtio-net.c               | 53 +++++++++++++++++++++----------
 include/hw/virtio/vhost-backend.h |  7 ++++
 include/net/vhost_net.h           |  4 +++
 5 files changed, 79 insertions(+), 17 deletions(-)

diff --git a/hw/net/vhost_net-stub.c b/hw/net/vhost_net-stub.c
index 89d71cfb8e..cc05e07c1f 100644
--- a/hw/net/vhost_net-stub.c
+++ b/hw/net/vhost_net-stub.c
@@ -101,3 +101,13 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 {
     return 0;
 }
+
+int vhost_net_get_rss(struct vhost_net *net, VirtioNetRssCapa *rss_capa)
+{
+    return 0;
+}
+
+int vhost_net_set_rss(struct vhost_net *net, VirtioNetRssData *rss_data)
+{
+    return 0;
+}
diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 30379d2ca4..aa2a1e8e5f 100644
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -512,3 +512,25 @@ int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu)
 
     return vhost_ops->vhost_net_set_mtu(&net->dev, mtu);
 }
+
+int vhost_net_get_rss(struct vhost_net *net, VirtioNetRssCapa *rss_capa)
+{
+    const VhostOps *vhost_ops = net->dev.vhost_ops;
+
+    if (!vhost_ops->vhost_net_get_rss) {
+        return 0;
+    }
+
+    return vhost_ops->vhost_net_get_rss(&net->dev, rss_capa);
+}
+
+int vhost_net_set_rss(struct vhost_net *net, VirtioNetRssData *rss_data)
+{
+    const VhostOps *vhost_ops = net->dev.vhost_ops;
+
+    if (!vhost_ops->vhost_net_set_rss) {
+        return 0;
+    }
+
+    return vhost_ops->vhost_net_set_rss(&net->dev, rss_data);
+}
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 38436e472b..237bbdb1b3 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -741,8 +741,10 @@ static uint64_t virtio_net_get_features(VirtIODevice 
*vdev, uint64_t features,
         return features;
     }
 
-    if (!ebpf_rss_is_loaded(&n->ebpf_rss)) {
-        virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
+    if (nc->peer->info->type == NET_CLIENT_DRIVER_TAP) {
+        if (!ebpf_rss_is_loaded(&n->ebpf_rss)) {
+            virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
+        }
     }
     features = vhost_net_get_features(get_vhost_net(nc->peer), features);
     vdev->backend_features = features;
@@ -1161,11 +1163,17 @@ static void virtio_net_detach_epbf_rss(VirtIONet *n);
 
 static void virtio_net_disable_rss(VirtIONet *n)
 {
+    NetClientState *nc = qemu_get_queue(n->nic);
+
     if (n->rss_data.enabled) {
         trace_virtio_net_rss_disable();
     }
     n->rss_data.enabled = false;
 
+    if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
+        vhost_net_set_rss(get_vhost_net(nc->peer), &n->rss_data);
+    }
+
     virtio_net_detach_epbf_rss(n);
 }
 
@@ -1239,6 +1247,7 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
                                       bool do_rss)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(n);
+    NetClientState *nc = qemu_get_queue(n->nic);
     struct virtio_net_rss_config cfg;
     size_t s, offset = 0, size_get;
     uint16_t queue_pairs, i;
@@ -1354,22 +1363,29 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
     }
     n->rss_data.enabled = true;
 
-    if (!n->rss_data.populate_hash) {
-        if (!virtio_net_attach_epbf_rss(n)) {
-            /* EBPF must be loaded for vhost */
-            if (get_vhost_net(qemu_get_queue(n->nic)->peer)) {
-                warn_report("Can't load eBPF RSS for vhost");
-                goto error;
+    if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
+        if (vhost_net_set_rss(get_vhost_net(nc->peer), &n->rss_data)) {
+            warn_report("Failed to configure RSS for vhost-user");
+            goto error;
+        }
+    } else {
+        if (!n->rss_data.populate_hash) {
+            if (!virtio_net_attach_epbf_rss(n)) {
+                /* EBPF must be loaded for vhost */
+                if (get_vhost_net(nc->peer)) {
+                    warn_report("Can't load eBPF RSS for vhost");
+                    goto error;
+                }
+                /* fallback to software RSS */
+                warn_report("Can't load eBPF RSS - fallback to software RSS");
+                n->rss_data.enabled_software_rss = true;
             }
-            /* fallback to software RSS */
-            warn_report("Can't load eBPF RSS - fallback to software RSS");
+        } else {
+            /* use software RSS for hash populating */
+            /* and detach eBPF if was loaded before */
+            virtio_net_detach_epbf_rss(n);
             n->rss_data.enabled_software_rss = true;
         }
-    } else {
-        /* use software RSS for hash populating */
-        /* and detach eBPF if was loaded before */
-        virtio_net_detach_epbf_rss(n);
-        n->rss_data.enabled_software_rss = true;
     }
 
     trace_virtio_net_rss_enable(n->rss_data.hash_types,
@@ -3534,8 +3550,11 @@ static void virtio_net_device_realize(DeviceState *dev, 
Error **errp)
         n->rss_capa.max_key_size = VIRTIO_NET_RSS_DEFAULT_KEY_SIZE;
         n->rss_capa.max_indirection_len = VIRTIO_NET_RSS_DEFAULT_TABLE_LEN;
         n->rss_capa.supported_hashes = VIRTIO_NET_RSS_SUPPORTED_HASHES;
-
-        virtio_net_load_ebpf(n);
+        if (nc->peer && nc->peer->info->type == NET_CLIENT_DRIVER_VHOST_USER) {
+            vhost_net_get_rss(get_vhost_net(nc->peer), &n->rss_capa);
+        } else {
+            virtio_net_load_ebpf(n);
+        }
     } else {
         n->rss_capa.max_indirection_len = 1;
     }
diff --git a/include/hw/virtio/vhost-backend.h 
b/include/hw/virtio/vhost-backend.h
index 81bf3109f8..0b9e2ea26e 100644
--- a/include/hw/virtio/vhost-backend.h
+++ b/include/hw/virtio/vhost-backend.h
@@ -12,6 +12,7 @@
 #define VHOST_BACKEND_H
 
 #include "exec/memory.h"
+#include "hw/virtio/virtio-net.h"
 
 typedef enum VhostBackendType {
     VHOST_BACKEND_TYPE_NONE = 0,
@@ -45,6 +46,10 @@ typedef int (*vhost_backend_memslots_limit)(struct vhost_dev 
*dev);
 typedef int (*vhost_net_set_backend_op)(struct vhost_dev *dev,
                                 struct vhost_vring_file *file);
 typedef int (*vhost_net_set_mtu_op)(struct vhost_dev *dev, uint16_t mtu);
+typedef int (*vhost_net_get_rss_op)(struct vhost_dev *dev,
+                                VirtioNetRssCapa *rss_capa);
+typedef int (*vhost_net_set_rss_op)(struct vhost_dev *dev,
+                                VirtioNetRssData *rss_data);
 typedef int (*vhost_scsi_set_endpoint_op)(struct vhost_dev *dev,
                                   struct vhost_scsi_target *target);
 typedef int (*vhost_scsi_clear_endpoint_op)(struct vhost_dev *dev,
@@ -133,6 +138,8 @@ typedef struct VhostOps {
     vhost_backend_memslots_limit vhost_backend_memslots_limit;
     vhost_net_set_backend_op vhost_net_set_backend;
     vhost_net_set_mtu_op vhost_net_set_mtu;
+    vhost_net_get_rss_op vhost_net_get_rss;
+    vhost_net_set_rss_op vhost_net_set_rss;
     vhost_scsi_set_endpoint_op vhost_scsi_set_endpoint;
     vhost_scsi_clear_endpoint_op vhost_scsi_clear_endpoint;
     vhost_scsi_get_abi_version_op vhost_scsi_get_abi_version;
diff --git a/include/net/vhost_net.h b/include/net/vhost_net.h
index 387e913e4e..9cf702e7e3 100644
--- a/include/net/vhost_net.h
+++ b/include/net/vhost_net.h
@@ -48,4 +48,8 @@ uint64_t vhost_net_get_acked_features(VHostNetState *net);
 
 int vhost_net_set_mtu(struct vhost_net *net, uint16_t mtu);
 
+int vhost_net_get_rss(struct vhost_net *net, VirtioNetRssCapa *rss_capa);
+
+int vhost_net_set_rss(struct vhost_net *net, VirtioNetRssData *rss_data);
+
 #endif
-- 
2.35.1