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

[Andrew Melnychenko <andrew@daynix.com>]

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@daynix.com>
---
 hw/net/virtio-net.c            | 96 +++++++++++++++++++++++++++++++---
 include/hw/virtio/virtio-net.h |  1 +
 2 files changed, 91 insertions(+), 6 deletions(-)

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 53e1c326433..9b3a997d872 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 +1306,96 @@ 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,
+                                       Error **errp)
 {
-    if (!virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
-        /* backend does't support steering ebpf */
-        return false;
+    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;
+        }
+    }
+
+    if (cur != NULL) {
+        /* the string contains more arguments */
+        error_setg(errp,
+                   "Too many eBPF file descriptors for RSS provided.");
+    } else if (i < nfds) {
+        error_setg(errp,
+                   "Not enough eBPF file descriptors for RSS were provided.");
+    }
+
+    return i;
+}
+
+static bool virtio_net_load_ebpf_fds(VirtIONet *n, Error **errp)
+{
+    char *fds_strs[EBPF_RSS_MAX_FDS];
+    int fds[EBPF_RSS_MAX_FDS];
+    int nfds;
+    int ret = true;
+    int i = 0;
+
+    ERRP_GUARD();
+
+    nfds = virtio_net_get_ebpf_rss_fds(n->ebpf_rss_fds,
+                                       fds_strs, EBPF_RSS_MAX_FDS, errp);
+    if (*errp) {
+        ret = false;
+        goto exit;
     }
 
-    return ebpf_rss_load(&n->ebpf_rss);
+    for (i = 0; i < nfds; i++) {
+        fds[i] = monitor_fd_param(monitor_cur(), fds_strs[i], errp);
+        if (*errp) {
+            ret = false;
+            goto exit;
+        }
+    }
+
+    ret = ebpf_rss_load_fds(&n->ebpf_rss, fds[0], fds[1], fds[2], fds[3]);
+
+exit:
+    if (!ret || *errp) {
+        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, Error **errp)
+{
+    bool ret = false;
+
+    if (virtio_net_attach_ebpf_to_backend(n->nic, -1)) {
+        if (!(n->ebpf_rss_fds
+                && virtio_net_load_ebpf_fds(n, errp))) {
+            ret = ebpf_rss_load(&n->ebpf_rss);
+        }
+    }
+
+    return ret;
 }
 
 static void virtio_net_unload_ebpf(VirtIONet *n)
@@ -3738,7 +3821,7 @@ 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);
+        virtio_net_load_ebpf(n, errp);
     }
 }
 
@@ -3900,6 +3983,7 @@ 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 ef234ffe7ef..e10ce88f918 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