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

[Jason Wang <jasowang@redhat.com>]

在 2022/4/8 20:28, Maxime Coquelin 写道:
> 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);


I wonder if we need a command parameter for the capability instead of 
silently get those from the vhost-user backhand (since there's no 
guarantee that the capability in src and dst are matched).

Thanks



> +        } 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