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

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Date:   Wed, 29 Mar 2023 13:45:43 +0300
From:   Andrew Melnychenko <andrew@...nix.com>
To:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, mst@...hat.com, jasowang@...hat.com,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        virtualization@...ts.linux-foundation.org
Cc:     yan@...nix.com, yuri.benditovich@...nix.com
Subject: [RFC PATCH 2/5] virtio-net: Added property to load eBPF RSS with fds.

eBPF RSS program and maps may now be passed during initialization.
Initially was implemented for libvirt to launch qemu without permissions,
and initialized eBPF program through the helper.

Signed-off-by: Andrew Melnychenko <andrew@...nix.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 53e1c32643..45d448a83d 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -42,6 +42,7 @@
 #include "sysemu/sysemu.h"
 #include "trace.h"
 #include "monitor/qdev.h"
+#include "monitor/monitor.h"
 #include "hw/pci/pci_device.h"
 #include "net_rx_pkt.h"
 #include "hw/virtio/vhost.h"
@@ -1305,14 +1306,81 @@ 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)
+{
+    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)
 {
-    if (!virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
-        /* backend does't support steering ebpf */
+    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)
@@ -3900,6 +3968,7 @@ 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 ef234ffe7e..e10ce88f91 100644
--- a/include/hw/virtio/virtio-net.h
+++ b/include/hw/virtio/virtio-net.h
@@ -219,6 +219,7 @@ struct VirtIONet {
     VirtioNetRssData rss_data;
     struct NetRxPkt *rx_pkt;
     struct EBPFRSSContext ebpf_rss;
+    char *ebpf_rss_fds;
 };
 
 size_t virtio_net_handle_ctrl_iov(VirtIODevice *vdev,
-- 
2.39.1