[PULL 04/97] virtio-net: Retrieve peer hashing capability

["Michael S. Tsirkin" <mst@redhat.com>]

From: Akihiko Odaki <akihiko.odaki@daynix.com>

Retrieve peer hashing capability instead of hardcoding.

Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20250530-vdpa-v1-4-5af4109b1c19@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
---
 include/hw/virtio/virtio-net.h |  5 ++-
 hw/net/virtio-net.c            | 71 +++++++++++++++++++++++++++-------
 net/vhost-vdpa.c               |  4 +-
 3 files changed, 64 insertions(+), 16 deletions(-)

diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
index b9ea9e824e..c4957c44c0 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -144,7 +144,10 @@ typedef struct VirtioNetRssData {
     bool    enabled_software_rss;
     bool    redirect;
     bool    populate_hash;
-    uint32_t hash_types;
+    bool    peer_hash_available;
+    uint32_t runtime_hash_types;
+    uint32_t supported_hash_types;
+    uint32_t peer_hash_types;
     uint8_t key[VIRTIO_NET_RSS_MAX_KEY_SIZE];
     uint16_t indirections_len;
     uint16_t *indirections_table;
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 34fe5909c5..9888ff22bd 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -158,7 +158,7 @@ static void virtio_net_get_config(VirtIODevice *vdev, uint8_t *config)
                  virtio_host_has_feature(vdev, VIRTIO_NET_F_RSS) ?
                  VIRTIO_NET_RSS_MAX_TABLE_LEN : 1);
     virtio_stl_p(vdev, &netcfg.supported_hash_types,
-                 VIRTIO_NET_RSS_SUPPORTED_HASHES);
+                 n->rss_data.supported_hash_types);
     memcpy(config, &netcfg, n->config_size);
 
     /*
@@ -1178,7 +1178,7 @@ static void rss_data_to_rss_config(struct VirtioNetRssData *data,
 {
     config->redirect = data->redirect;
     config->populate_hash = data->populate_hash;
-    config->hash_types = data->hash_types;
+    config->hash_types = data->runtime_hash_types;
     config->indirections_len = data->indirections_len;
     config->default_queue = data->default_queue;
 }
@@ -1213,6 +1213,10 @@ static void virtio_net_detach_ebpf_rss(VirtIONet *n)
 
 static void virtio_net_commit_rss_config(VirtIONet *n)
 {
+    if (n->rss_data.peer_hash_available) {
+        return;
+    }
+
     if (n->rss_data.enabled) {
         n->rss_data.enabled_software_rss = n->rss_data.populate_hash;
         if (n->rss_data.populate_hash) {
@@ -1227,7 +1231,7 @@ static void virtio_net_commit_rss_config(VirtIONet *n)
         }
 
         trace_virtio_net_rss_enable(n,
-                                    n->rss_data.hash_types,
+                                    n->rss_data.runtime_hash_types,
                                     n->rss_data.indirections_len,
                                     sizeof(n->rss_data.key));
     } else {
@@ -1338,7 +1342,7 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
         err_value = (uint32_t)s;
         goto error;
     }
-    n->rss_data.hash_types = virtio_ldl_p(vdev, &cfg.hash_types);
+    n->rss_data.runtime_hash_types = virtio_ldl_p(vdev, &cfg.hash_types);
     n->rss_data.indirections_len =
         virtio_lduw_p(vdev, &cfg.indirection_table_mask);
     if (!do_rss) {
@@ -1401,12 +1405,12 @@ static uint16_t virtio_net_handle_rss(VirtIONet *n,
         err_value = temp.b;
         goto error;
     }
-    if (!temp.b && n->rss_data.hash_types) {
+    if (!temp.b && n->rss_data.runtime_hash_types) {
         err_msg = "No key provided";
         err_value = 0;
         goto error;
     }
-    if (!temp.b && !n->rss_data.hash_types) {
+    if (!temp.b && !n->rss_data.runtime_hash_types) {
         virtio_net_disable_rss(n);
         return queue_pairs;
     }
@@ -1808,7 +1812,7 @@ static int virtio_net_process_rss(NetClientState *nc, const uint8_t *buf,
     net_rx_pkt_set_protocols(pkt, &iov, 1, n->host_hdr_len);
     net_rx_pkt_get_protocols(pkt, &hasip4, &hasip6, &l4hdr_proto);
     net_hash_type = virtio_net_get_hash_type(hasip4, hasip6, l4hdr_proto,
-                                             n->rss_data.hash_types);
+                                             n->rss_data.runtime_hash_types);
     if (net_hash_type > NetPktRssIpV6UdpEx) {
         if (n->rss_data.populate_hash) {
             hdr->hash_value = VIRTIO_NET_HASH_REPORT_NONE;
@@ -3008,6 +3012,14 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features,
 {
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc = qemu_get_queue(n->nic);
+    uint32_t supported_hash_types = n->rss_data.supported_hash_types;
+    uint32_t peer_hash_types = n->rss_data.peer_hash_types;
+    bool use_own_hash =
+        (supported_hash_types & VIRTIO_NET_RSS_SUPPORTED_HASHES) ==
+        supported_hash_types;
+    bool use_peer_hash =
+        n->rss_data.peer_hash_available &&
+        (supported_hash_types & peer_hash_types) == supported_hash_types;
 
     /* Firstly sync all virtio-net possible supported features */
     features |= n->host_features;
@@ -3044,12 +3056,28 @@ static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features,
     }
 
     if (!get_vhost_net(nc->peer)) {
+        if (!use_own_hash) {
+            virtio_clear_feature(&features, VIRTIO_NET_F_HASH_REPORT);
+            virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
+        } else if (virtio_has_feature(features, VIRTIO_NET_F_RSS)) {
+            virtio_net_load_ebpf(n, errp);
+        }
+
         return features;
     }
 
-    if (!ebpf_rss_is_loaded(&n->ebpf_rss)) {
-        virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
+    if (!use_peer_hash) {
+        virtio_clear_feature(&features, VIRTIO_NET_F_HASH_REPORT);
+
+        if (!use_own_hash || !virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
+            if (!virtio_net_load_ebpf(n, errp)) {
+                return features;
+            }
+
+            virtio_clear_feature(&features, VIRTIO_NET_F_RSS);
+        }
     }
+
     features = vhost_net_get_features(get_vhost_net(nc->peer), features);
     vdev->backend_features = features;
 
@@ -3314,6 +3342,17 @@ static const VMStateDescription vmstate_virtio_net_has_vnet = {
     },
 };
 
+static int virtio_net_rss_post_load(void *opaque, int version_id)
+{
+    VirtIONet *n = VIRTIO_NET(opaque);
+
+    if (version_id == 1) {
+        n->rss_data.supported_hash_types = VIRTIO_NET_RSS_SUPPORTED_HASHES;
+    }
+
+    return 0;
+}
+
 static bool virtio_net_rss_needed(void *opaque)
 {
     return VIRTIO_NET(opaque)->rss_data.enabled;
@@ -3321,14 +3360,16 @@ static bool virtio_net_rss_needed(void *opaque)
 
 static const VMStateDescription vmstate_virtio_net_rss = {
     .name      = "virtio-net-device/rss",
-    .version_id = 1,
+    .version_id = 2,
     .minimum_version_id = 1,
+    .post_load = virtio_net_rss_post_load,
     .needed = virtio_net_rss_needed,
     .fields = (const VMStateField[]) {
         VMSTATE_BOOL(rss_data.enabled, VirtIONet),
         VMSTATE_BOOL(rss_data.redirect, VirtIONet),
         VMSTATE_BOOL(rss_data.populate_hash, VirtIONet),
-        VMSTATE_UINT32(rss_data.hash_types, VirtIONet),
+        VMSTATE_UINT32(rss_data.runtime_hash_types, VirtIONet),
+        VMSTATE_UINT32_V(rss_data.supported_hash_types, VirtIONet, 2),
         VMSTATE_UINT16(rss_data.indirections_len, VirtIONet),
         VMSTATE_UINT16(rss_data.default_queue, VirtIONet),
         VMSTATE_UINT8_ARRAY(rss_data.key, VirtIONet,
@@ -3915,8 +3956,12 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
 
     net_rx_pkt_init(&n->rx_pkt);
 
-    if (virtio_has_feature(n->host_features, VIRTIO_NET_F_RSS)) {
-        virtio_net_load_ebpf(n, errp);
+    if (qemu_get_vnet_hash_supported_types(qemu_get_queue(n->nic)->peer,
+                                           &n->rss_data.peer_hash_types)) {
+        n->rss_data.peer_hash_available = true;
+        n->rss_data.supported_hash_types = n->rss_data.peer_hash_types;
+    } else {
+        n->rss_data.supported_hash_types = VIRTIO_NET_RSS_SUPPORTED_HASHES;
     }
 }
 
diff --git a/net/vhost-vdpa.c b/net/vhost-vdpa.c
index cb63e09453..3452835ca9 100644
--- a/net/vhost-vdpa.c
+++ b/net/vhost-vdpa.c
@@ -865,13 +865,13 @@ static int vhost_vdpa_net_load_rss(VhostVDPAState *s, const VirtIONet *n,
      * configuration only at live migration.
      */
     if (!n->rss_data.enabled ||
-        n->rss_data.hash_types == VIRTIO_NET_HASH_REPORT_NONE) {
+        n->rss_data.runtime_hash_types == VIRTIO_NET_HASH_REPORT_NONE) {
         return 0;
     }
 
     table = g_malloc_n(n->rss_data.indirections_len,
                        sizeof(n->rss_data.indirections_table[0]));
-    cfg.hash_types = cpu_to_le32(n->rss_data.hash_types);
+    cfg.hash_types = cpu_to_le32(n->rss_data.runtime_hash_types);
 
     if (do_rss) {
         /*
-- 
MST