Re: [PATCH v2 3/4] virtio-net: implement RX RSS processing

[Yuri Benditovich <yuri.benditovich@daynix.com>]

On Tue, Mar 10, 2020 at 5:10 AM Jason Wang <jasowang@redhat.com> wrote:
>
>
> On 2020/3/9 下午4:34, Yuri Benditovich wrote:
> > If VIRTIO_NET_F_RSS negotiated and RSS is enabled, process
> > incoming packets, calculate packet's hash and place the
> > packet into respective RX virtqueue.
> >
> > Signed-off-by: Yuri Benditovich <yuri.benditovich@daynix.com>
> > ---
> >   hw/net/virtio-net.c            | 86 +++++++++++++++++++++++++++++++++-
> >   include/hw/virtio/virtio-net.h |  1 +
> >   2 files changed, 85 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> > index 27071eccd2..abc41fdb16 100644
> > --- a/hw/net/virtio-net.c
> > +++ b/hw/net/virtio-net.c
> > @@ -42,6 +42,7 @@
> >   #include "trace.h"
> >   #include "monitor/qdev.h"
> >   #include "hw/pci/pci.h"
> > +#include "net_rx_pkt.h"
> >
> >   #define VIRTIO_NET_VM_VERSION    11
> >
> > @@ -1610,8 +1611,78 @@ static int receive_filter(VirtIONet *n, const uint8_t *buf, int size)
> >       return 0;
> >   }
> >
> > +static uint8_t virtio_net_get_hash_type(bool isip4,
> > +                                        bool isip6,
> > +                                        bool isudp,
> > +                                        bool istcp,
> > +                                        uint32_t types)
> > +{
> > +    uint32_t mask;
> > +    if (isip4) {
> > +        if (istcp && (types & VIRTIO_NET_RSS_HASH_TYPE_TCPv4)) {
> > +            return NetPktRssIpV4Tcp;
> > +        }
> > +        if (isudp && (types & VIRTIO_NET_RSS_HASH_TYPE_UDPv4)) {
> > +            return NetPktRssIpV4Udp;
> > +        }
> > +        if (types & VIRTIO_NET_RSS_HASH_TYPE_IPv4) {
> > +            return NetPktRssIpV4;
> > +        }
> > +    } else if (isip6) {
> > +        mask = VIRTIO_NET_RSS_HASH_TYPE_TCP_EX | VIRTIO_NET_RSS_HASH_TYPE_TCPv6;
> > +        if (istcp && (types & mask)) {
> > +            return (types & VIRTIO_NET_RSS_HASH_TYPE_TCP_EX) ?
> > +                NetPktRssIpV6TcpEx : NetPktRssIpV6Tcp;
> > +        }
> > +        mask = VIRTIO_NET_RSS_HASH_TYPE_UDP_EX | VIRTIO_NET_RSS_HASH_TYPE_UDPv6;
> > +        if (isudp && (types & mask)) {
> > +            return (types & VIRTIO_NET_RSS_HASH_TYPE_UDP_EX) ?
> > +                NetPktRssIpV6UdpEx : NetPktRssIpV6Udp;
> > +        }
> > +        mask = VIRTIO_NET_RSS_HASH_TYPE_IP_EX | VIRTIO_NET_RSS_HASH_TYPE_IPv6;
> > +        if (types & mask) {
> > +            return (types & VIRTIO_NET_RSS_HASH_TYPE_IP_EX) ?
> > +                NetPktRssIpV6Ex : NetPktRssIpV6;
> > +        }
> > +    }
> > +    return 0xff;
> > +}
> > +
> > +static int virtio_net_process_rss(NetClientState *nc, const uint8_t *buf,
> > +                                  size_t size)
> > +{
> > +    VirtIONet *n = qemu_get_nic_opaque(nc);
> > +    unsigned int index = nc->queue_index, new_index;
> > +    struct NetRxPkt *pkt = n->rss_data.pkt;
> > +    uint8_t net_hash_type;
> > +    uint32_t hash;
> > +    bool isip4, isip6, isudp, istcp;
> > +    net_rx_pkt_set_protocols(pkt, buf + n->host_hdr_len,
> > +                             size - n->host_hdr_len);
> > +    net_rx_pkt_get_protocols(pkt, &isip4, &isip6, &isudp, &istcp);
> > +    if (isip4 && (net_rx_pkt_get_ip4_info(pkt)->fragment)) {
> > +        istcp = isudp = false;
> > +    }
> > +    if (isip6 && (net_rx_pkt_get_ip6_info(pkt)->fragment)) {
> > +        istcp = isudp = false;
> > +    }
> > +    net_hash_type = virtio_net_get_hash_type(isip4, isip6, isudp, istcp,
> > +                                             n->rss_data.hash_types);
> > +    if (net_hash_type > NetPktRssIpV6UdpEx) {
> > +        return n->rss_data.default_queue;
> > +    }
> > +
> > +    hash = net_rx_pkt_calc_rss_hash(pkt, net_hash_type, n->rss_data.key);
> > +    new_index = hash & (n->rss_data.indirections_len - 1);
> > +    new_index = n->rss_data.indirections[new_index];
> > +    if (index == new_index) {
> > +        return -1;
> > +    }
> > +    return new_index;
> > +}
> > +
> >   static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
> > -                                      size_t size)
> > +                                      size_t size, bool no_rss)
> >   {
> >       VirtIONet *n = qemu_get_nic_opaque(nc);
> >       VirtIONetQueue *q = virtio_net_get_subqueue(nc);
> > @@ -1625,6 +1696,14 @@ static ssize_t virtio_net_receive_rcu(NetClientState *nc, const uint8_t *buf,
> >           return -1;
> >       }
> >
> > +    if (!no_rss && n->rss_data.enabled) {
> > +        int index = virtio_net_process_rss(nc, buf, size);
> > +        if (index >= 0) {
> > +            NetClientState *nc2 = qemu_get_subqueue(n->nic, index);
> > +            return virtio_net_receive_rcu(nc2, buf, size, true);
> > +        }
> > +    }
>
>
> In the long run, we need to implement steering ops and allow device
> model to implement their own policy instead of doing hack like this.
>

Are you talking about support for RSS in tap driver or about something
different?

> Thanks
>
>
> > +
> >       /* hdr_len refers to the header we supply to the guest */
> >       if (!virtio_net_has_buffers(q, size + n->guest_hdr_len - n->host_hdr_len)) {
> >           return 0;
> > @@ -1719,7 +1798,7 @@ static ssize_t virtio_net_do_receive(NetClientState *nc, const uint8_t *buf,
> >   {
> >       RCU_READ_LOCK_GUARD();
> >
> > -    return virtio_net_receive_rcu(nc, buf, size);
> > +    return virtio_net_receive_rcu(nc, buf, size, false);
> >   }
> >
> >   static void virtio_net_rsc_extract_unit4(VirtioNetRscChain *chain,
> > @@ -3295,6 +3374,8 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
> >
> >       QTAILQ_INIT(&n->rsc_chains);
> >       n->qdev = dev;
> > +
> > +    net_rx_pkt_init(&n->rss_data.pkt, false);
> >   }
> >
> >   static void virtio_net_device_unrealize(DeviceState *dev, Error **errp)
> > @@ -3331,6 +3412,7 @@ static void virtio_net_device_unrealize(DeviceState *dev, Error **errp)
> >       g_free(n->vqs);
> >       qemu_del_nic(n->nic);
> >       virtio_net_rsc_cleanup(n);
> > +    net_rx_pkt_uninit(n->rss_data.pkt);
> >       virtio_cleanup(vdev);
> >   }
> >
> > diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
> > index cf16f5192e..45670dd054 100644
> > --- a/include/hw/virtio/virtio-net.h
> > +++ b/include/hw/virtio/virtio-net.h
> > @@ -209,6 +209,7 @@ struct VirtIONet {
> >           uint16_t indirections[VIRTIO_NET_RSS_MAX_TABLE_LEN];
> >           uint16_t indirections_len;
> >           uint16_t default_queue;
> > +        struct NetRxPkt *pkt;
> >       } rss_data;
> >   };
> >
>