Re: [PATCH 2/5] virtio-net: Added property to load eBPF RSS with fds.

[Jason Wang <jasowang@redhat.com>]

在 2021/7/13 下午11:37, Andrew Melnychenko 写道:
> eBPF RSS program and maps now may be passed during initialization.
> Initially was implemented for libvirt to launch qemu without permissions.
>
> Signed-off-by: Andrew Melnychenko <andrew@daynix.com>
> ---
>   hw/net/virtio-net.c            | 77 ++++++++++++++++++++++++++++++++--
>   include/hw/virtio/virtio-net.h |  1 +
>   2 files changed, 74 insertions(+), 4 deletions(-)
>
> diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
> index bd7958b9f0..0602b1772e 100644
> --- a/hw/net/virtio-net.c
> +++ b/hw/net/virtio-net.c
> @@ -41,6 +41,7 @@
>   #include "sysemu/sysemu.h"
>   #include "trace.h"
>   #include "monitor/qdev.h"
> +#include "monitor/monitor.h"
>   #include "hw/pci/pci.h"
>   #include "net_rx_pkt.h"
>   #include "hw/virtio/vhost.h"
> @@ -1223,14 +1224,81 @@ static void virtio_net_detach_epbf_rss(VirtIONet *n)
>       virtio_net_attach_ebpf_to_backend(n->nic, -1);
>   }
>   
> -static bool virtio_net_load_ebpf(VirtIONet *n)
> +static int virtio_net_get_ebpf_rss_fds(char *str, char *fds[], int nfds)
>   {
> -    if (!virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
> -        /* backend does't support steering ebpf */
> +    char *ptr = str;
> +    char *cur = NULL;
> +    size_t len = strlen(str);
> +    int i = 0;
> +
> +    for (; i < nfds && ptr < str + len;) {
> +        cur = strchr(ptr, ':');
> +
> +        if (cur == NULL) {
> +            fds[i] = g_strdup(ptr);
> +        } else {
> +            fds[i] = g_strndup(ptr, cur - ptr);
> +        }
> +
> +        i++;
> +        if (cur == NULL) {
> +            break;
> +        } else {
> +            ptr = cur + 1;
> +        }
> +    }
> +
> +    return i;
> +}
> +
> +static bool virtio_net_load_ebpf_fds(VirtIONet *n)
> +{
> +    char *fds_strs[EBPF_RSS_MAX_FDS];
> +    int fds[EBPF_RSS_MAX_FDS];
> +    int nfds;
> +    int ret = false;
> +    Error *errp;
> +    int i = 0;
> +
> +    if (n == NULL || !n->ebpf_rss_fds) {
>           return false;
>       }
>   
> -    return ebpf_rss_load(&n->ebpf_rss);
> +    nfds = virtio_net_get_ebpf_rss_fds(n->ebpf_rss_fds,
> +                                       fds_strs, EBPF_RSS_MAX_FDS);
> +    for (i = 0; i < nfds; i++) {
> +        fds[i] = monitor_fd_param(monitor_cur(), fds_strs[i], &errp);
> +    }
> +
> +    if (nfds == EBPF_RSS_MAX_FDS) {
> +        ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]);
> +    }
> +
> +    if (!ret) {
> +        for (i = 0; i < nfds; i++) {
> +            close(fds[i]);
> +        }
> +    }
> +
> +    for (i = 0; i < nfds; i++) {
> +        g_free(fds_strs[i]);
> +    }
> +
> +    return ret;
> +}
> +
> +static bool virtio_net_load_ebpf(VirtIONet *n)
> +{
> +    bool ret = true;
> +
> +    if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
> +        if (!(n->ebpf_rss_fds
> +                && virtio_net_load_ebpf_fds(n))) {
> +            ret = ebpf_rss_load(&n->ebpf_rss);
> +        }
> +    }
> +
> +    return ret;
>   }
>   
>   static void virtio_net_unload_ebpf(VirtIONet *n)
> @@ -3605,6 +3673,7 @@ static Property virtio_net_properties[] = {
>                       VIRTIO_NET_F_RSS, false),
>       DEFINE_PROP_BIT64("hash", VirtIONet, host_features,
>                       VIRTIO_NET_F_HASH_REPORT, false),
> +    DEFINE_PROP_STRING("ebpf_rss_fds", VirtIONet, ebpf_rss_fds),
>       DEFINE_PROP_BIT64("guest_rsc_ext", VirtIONet, host_features,
>                       VIRTIO_NET_F_RSC_EXT, false),
>       DEFINE_PROP_UINT32("rsc_interval", VirtIONet, rsc_timeout,
> diff --git a/include/hw/virtio/virtio-net.h b/include/hw/virtio/virtio-net.h
> index 824a69c23f..993f2f3036 100644
> --- a/include/hw/virtio/virtio-net.h
> +++ b/include/hw/virtio/virtio-net.h
> @@ -213,6 +213,7 @@ struct VirtIONet {
>       VirtioNetRssData rss_data;
>       struct NetRxPkt *rx_pkt;
>       struct EBPFRSSContext ebpf_rss;
> +    char *ebpf_rss_fds;


I wonder if it's better to use separated properties instead of implying 
an order here?

E.g "program_fd", "key_map_fd", "indirection_table_map_fd" etc.

Thanks


>   };
>   
>   void virtio_net_set_netclient_name(VirtIONet *n, const char *name,