vhost-user: add vhost-user

add virtio and vhost-user functions to connect with QEMU.

  $ ./passt --vhost-user

and

  # qemu-system-x86_64 ... -m 4G \
        -object memory-backend-memfd,id=memfd0,share=on,size=4G \
        -numa node,memdev=memfd0 \
        -chardev socket,id=chr0,path=/tmp/passt_1.socket \
        -netdev vhost-user,id=netdev0,chardev=chr0 \
        -device virtio-net,mac=9a:2b:2c:2d:2e:2f,netdev=netdev0 \
        ...

Signed-off-by: Laurent Vivier <lvivier@redhat.com>

conf.c

@@ -44,6 +44,7 @@
 #include "lineread.h"
 #include "isolation.h"
 #include "log.h"
+#include "vhost_user.h"
 
 /**
  * next_chunk - Return the next piece of a string delimited by a character
@@ -721,9 +722,12 @@ static void print_usage(const char *name, int status)
 		info(   "  -I, --ns-ifname NAME	namespace interface name");
 		info(   "    default: same interface name as external one");
 	} else {
-		info(   "  -s, --socket PATH	UNIX domain socket path");
+		info(   "  -s, --socket, --socket-path PATH	UNIX domain socket path");
 		info(   "    default: probe free path starting from "
 		     UNIX_SOCK_PATH, 1);
+		info(   "  --vhost-user		Enable vhost-user mode");
+		info(   "    UNIX domain socket is provided by -s option");
+		info(   "  --print-capabilities	print back-end capabilities in JSON format");
 	}
 
 	info(   "  -F, --fd FD		Use FD as pre-opened connected socket");
@@ -1109,6 +1113,7 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"help",	no_argument,		NULL,		'h' },
 		{"socket",	required_argument,	NULL,		's' },
 		{"fd",		required_argument,	NULL,		'F' },
+		{"socket-path",	required_argument,	NULL,		's' }, /* vhost-user mandatory */
 		{"ns-ifname",	required_argument,	NULL,		'I' },
 		{"pcap",	required_argument,	NULL,		'p' },
 		{"pid",		required_argument,	NULL,		'P' },
@@ -1155,6 +1160,8 @@ void conf(struct ctx *c, int argc, char **argv)
 		{"config-net",	no_argument,		NULL,		17 },
 		{"no-copy-routes", no_argument,		NULL,		18 },
 		{"no-copy-addrs", no_argument,		NULL,		19 },
+		{"vhost-user",	no_argument,		NULL,		20 },
+		{"print-capabilities", no_argument,	NULL,		21 }, /* vhost-user mandatory */
 		{ 0 },
 	};
 	char userns[PATH_MAX] = { 0 }, netns[PATH_MAX] = { 0 };
@@ -1314,7 +1321,6 @@ void conf(struct ctx *c, int argc, char **argv)
 				       sizeof(c->ip6.ifname_out), "%s", optarg);
 			if (ret <= 0 || ret >= (int)sizeof(c->ip6.ifname_out))
 				die("Invalid interface name: %s", optarg);
-
 			break;
 		case 17:
 			if (c->mode != MODE_PASTA)
@@ -1336,6 +1342,16 @@ void conf(struct ctx *c, int argc, char **argv)
 			warn("--no-copy-addrs will be dropped soon");
 			c->no_copy_addrs = copy_addrs_opt = true;
 			break;
+		case 20:
+			if (c->mode == MODE_PASTA) {
+				err("--vhost-user is for passt mode only");
+				usage(argv[0]);
+			}
+			c->mode = MODE_VU;
+			break;
+		case 21:
+			vu_print_capabilities();
+			break;
 		case 'd':
 			if (c->debug)
 				die("Multiple --debug options given");

passt.c

@@ -280,6 +280,7 @@ int main(int argc, char **argv)
 	pasta_netns_quit_init(&c);
 
 	tap_sock_init(&c);
+	vu_init(&c);
 
 	secret_init(&c);
 
@@ -390,6 +391,12 @@ loop:
 		case EPOLL_TYPE_ICMPV6:
 			icmp_sock_handler(&c, AF_INET6, ref);
 			break;
+		case EPOLL_TYPE_VHOST_CMD:
+			tap_handler_vu(&c, eventmask);
+			break;
+		case EPOLL_TYPE_VHOST_KICK:
+			vu_kick_cb(&c, ref);
+			break;
 		default:
 			/* Can't happen */
 			ASSERT(0);

passt.h

@@ -145,6 +145,7 @@ struct fqdn {
 enum passt_modes {
 	MODE_PASST,
 	MODE_PASTA,
+	MODE_VU,
 };
 
 /**

tap.c

@@ -58,6 +58,7 @@
 #include "packet.h"
 #include "tap.h"
 #include "log.h"
+#include "vhost_user.h"
 
 /* IPv4 (plus ARP) and IPv6 message batches from tap/guest to IP handlers */
 static PACKET_POOL_NOINIT(pool_tap4, TAP_MSGS, pkt_buf);
@@ -76,19 +77,22 @@ static PACKET_POOL_NOINIT(pool_tap6, TAP_MSGS, pkt_buf);
  */
 int tap_send(const struct ctx *c, const void *data, size_t len)
 {
+	int flags = MSG_NOSIGNAL | MSG_DONTWAIT;
+	uint32_t vnet_len = htonl(len);
+
 	pcap(data, len);
 
-	if (c->mode == MODE_PASST) {
+	switch (c->mode) {
-		int flags = MSG_NOSIGNAL | MSG_DONTWAIT;
+	case MODE_PASST:
-		uint32_t vnet_len = htonl(len);
-
 		if (send(c->fd_tap, &vnet_len, 4, flags) < 0)
 			return -1;
-
 		return send(c->fd_tap, data, len, flags);
+	case MODE_PASTA:
+		return write(c->fd_tap, (char *)data, len);
+	case MODE_VU:
+		return vu_send(c, data, len);
 	}
-
+	return 0;
-	return write(c->fd_tap, (char *)data, len);
 }
 
 /**
@@ -465,10 +469,20 @@ size_t tap_send_frames(const struct ctx *c, const struct iovec *iov, size_t n)
 	if (!n)
 		return 0;
 
-	if (c->mode == MODE_PASTA)
+	switch (c->mode) {
+	case MODE_PASTA:
 		m = tap_send_frames_pasta(c, iov, n);
-	else
+		break;
+	case MODE_PASST:
 		m = tap_send_frames_passt(c, iov, n);
+		break;
+	case MODE_VU:
+		m = tap_send_frames_vu(c, iov, n);
+		break;
+	default:
+		m = 0;
+		break;
+	}
 
 	if (m < n)
 		debug("tap: failed to send %zu frames of %zu", n - m, n);
@@ -1249,11 +1263,17 @@ static void tap_sock_unix_init(struct ctx *c)
 	ev.data.u64 = ref.u64;
 	epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap_listen, &ev);
 
-	info("You can now start qemu (>= 7.2, with commit 13c6be96618c):");
+	if (c->mode == MODE_VU) {
-	info("    kvm ... -device virtio-net-pci,netdev=s -netdev stream,id=s,server=off,addr.type=unix,addr.path=%s",
+		info("You can start qemu with:");
-	     addr.sun_path);
+		info("    kvm ... -chardev socket,id=chr0,path=%s -netdev vhost-user,id=netdev0,chardev=chr0 -device virtio-net,netdev=netdev0 -object memory-backend-memfd,id=memfd0,share=on,size=$RAMSIZE -numa node,memdev=memfd0\n",
-	info("or qrap, for earlier qemu versions:");
+		     addr.sun_path);
-	info("    ./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio");
+	} else {
+		info("You can now start qemu (>= 7.2, with commit 13c6be96618c):");
+		info("    kvm ... -device virtio-net-pci,netdev=s -netdev stream,id=s,server=off,addr.type=unix,addr.path=%s",
+		     addr.sun_path);
+		info("or qrap, for earlier qemu versions:");
+		info("    ./qrap 5 kvm ... -net socket,fd=5 -net nic,model=virtio");
+	}
 }
 
 /**
@@ -1263,7 +1283,7 @@ static void tap_sock_unix_init(struct ctx *c)
  */
 void tap_listen_handler(struct ctx *c, uint32_t events)
 {
-	union epoll_ref ref = { .type = EPOLL_TYPE_TAP_PASST };
+	union epoll_ref ref;
 	struct epoll_event ev = { 0 };
 	int v = INT_MAX / 2;
 	struct ucred ucred;
@@ -1304,7 +1324,13 @@ void tap_listen_handler(struct ctx *c, uint32_t events)
 		trace("tap: failed to set SO_SNDBUF to %i", v);
 
 	ref.fd = c->fd_tap;
-	ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+	if (c->mode == MODE_VU) {
+		ref.type = EPOLL_TYPE_VHOST_CMD;
+		ev.events = EPOLLIN | EPOLLRDHUP;
+	} else {
+		ref.type = EPOLL_TYPE_TAP_PASST;
+		ev.events = EPOLLIN | EPOLLRDHUP | EPOLLET;
+	}
 	ev.data.u64 = ref.u64;
 	epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev);
 }
@@ -1388,12 +1414,21 @@ void tap_sock_init(struct ctx *c)
 
 		ASSERT(c->one_off);
 		ref.fd = c->fd_tap;
-		if (c->mode == MODE_PASST)
+		switch (c->mode) {
+		case MODE_PASST:
 			ref.type = EPOLL_TYPE_TAP_PASST;
-		else
+			ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+			break;
+		case MODE_PASTA:
 			ref.type = EPOLL_TYPE_TAP_PASTA;
+			ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
+			break;
+		case MODE_VU:
+			ref.type = EPOLL_TYPE_VHOST_CMD;
+			ev.events = EPOLLIN | EPOLLRDHUP;
+			break;
+		}
 
-		ev.events = EPOLLIN | EPOLLET | EPOLLRDHUP;
 		ev.data.u64 = ref.u64;
 		epoll_ctl(c->epollfd, EPOLL_CTL_ADD, c->fd_tap, &ev);
 		return;

tcp.c

@@ -1049,7 +1049,8 @@ size_t tcp_fill_headers4(const struct ctx *c,
 
 	tcp_fill_header(th, conn, seq);
 
-	tcp_update_check_tcp4(iph, th);
+	if (c->mode != MODE_VU || *c->pcap)
+		tcp_update_check_tcp4(iph, th);
 
 	return ip_len;
 }
@@ -1090,7 +1091,8 @@ size_t tcp_fill_headers6(const struct ctx *c,
 
 	tcp_fill_header(th, conn, seq);
 
-	tcp_update_check_tcp6(ip6h, th);
+	if (c->mode != MODE_VU || *c->pcap)
+		tcp_update_check_tcp6(ip6h, th);
 
 	return ip_len;
 }

udp.c

@@ -681,9 +681,12 @@ static size_t udp_update_hdr6(const struct ctx *c, struct ipv6hdr *ip6h,
 	uh->dest = htons(dstport);
 	uh->len = ip6h->payload_len;
 	uh->check = 0;
-	uh->check = csum(uh, payload_len,
+	if (c->mode != MODE_VU || *c->pcap)
-			 proto_ipv6_header_psum(payload_len, IPPROTO_UDP,
+		uh->check = csum(uh, payload_len,
-						src, dst));
+				 proto_ipv6_header_psum(payload_len, IPPROTO_UDP,
+							src, dst));
+	else
+		uh->check = 0xffff; /* zero checksum is invalid with IPv6 */
 
 	return ip_len;
 }