xen/pvcalls: frontend enable

The Xen pvcalls frontend driver needs to be explicitly enabled, and
there isn't a way to do it upstream yet. This patch adds a simple
boolean command line option (gated on CONFIG_XEN_PVCALLS_FRONTEND) to
enable pvcalls. It is a temporary solution but it is the best we can do
until a proper upstream mechanism to enable pvcalls is introduced.

The patch has no effect if CONFIG_XEN_PVCALLS_FRONTEND is not enabled,
or if pvcalls=true is not passed as a command line argument.

Signed-off-by: Stefano Stabellini <[email protected]>
State: not-upstreamable
[michals: Squashed with
xen/pvcalls: change CONFIG_XEN_PVCALLS_FRONTEND to bool
]

Author: Stefano Stabellini

drivers/xen/Kconfig

@@ -229,7 +229,7 @@ config XEN_PCIDEV_BACKEND
 	  If in doubt, say m.
 
 config XEN_PVCALLS_FRONTEND
-	tristate "XEN PV Calls frontend driver"
+	bool "XEN PV Calls frontend driver"
 	depends on INET && XEN
 	select XEN_XENBUS_FRONTEND
 	help

drivers/xen/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_XEN_SCSI_BACKEND)		+= xen-scsiback.o
 obj-$(CONFIG_XEN_AUTO_XLATE)		+= xlate_mmu.o
 obj-$(CONFIG_XEN_PVCALLS_BACKEND)	+= pvcalls-back.o
 obj-$(CONFIG_XEN_PVCALLS_FRONTEND)	+= pvcalls-front.o
+obj-$(CONFIG_XEN_PVCALLS_FRONTEND)	+= pvcalls.o
 xen-evtchn-y				:= evtchn.o
 xen-gntdev-y				:= gntdev.o
 xen-gntdev-$(CONFIG_XEN_GNTDEV_DMABUF)	+= gntdev-dmabuf.o

drivers/xen/pvcalls.c

@@ -0,0 +1,134 @@
+#include <linux/types.h>
+#include <linux/bitops.h>
+#include <linux/cred.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/kmod.h>
+#include <linux/list.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/net.h>
+#include <linux/poll.h>
+#include <linux/skbuff.h>
+#include <linux/smp.h>
+#include <linux/socket.h>
+#include <linux/stddef.h>
+#include <linux/unistd.h>
+#include <linux/wait.h>
+#include <linux/workqueue.h>
+#include <net/sock.h>
+#include <net/inet_common.h>
+
+#include "pvcalls-front.h"
+
+static int
+pvcalls_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
+{
+	int ret;
+	ret = pvcalls_front_socket(sock);
+	if (ret < 0)
+		return ret;
+	return pvcalls_front_bind(sock, addr, addr_len);
+}
+
+static int pvcalls_stream_connect(struct socket *sock, struct sockaddr *addr,
+				int addr_len, int flags)
+{
+	int ret;
+	ret = pvcalls_front_socket(sock);
+	if (ret < 0)
+		return ret;
+	return pvcalls_front_connect(sock, addr, addr_len, flags);
+}
+
+static int pvcalls_accept(struct socket *sock, struct socket *newsock, int flags, bool kern)
+{
+	return pvcalls_front_accept(sock, newsock, flags);
+}
+
+static int pvcalls_getname(struct socket *sock,
+			 struct sockaddr *uaddr, int peer)
+{
+	DECLARE_SOCKADDR(struct sockaddr_in *, sin, uaddr);
+
+	sin->sin_family = AF_INET;
+	memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+	return 0;
+}
+
+static unsigned int pvcalls_poll(struct file *file, struct socket *sock,
+			       poll_table *wait)
+{
+	return pvcalls_front_poll(file, sock, wait);
+}
+
+static int pvcalls_listen(struct socket *sock, int backlog)
+{
+	return pvcalls_front_listen(sock, backlog);
+}
+
+static int pvcalls_stream_sendmsg(struct socket *sock, struct msghdr *msg,
+				size_t len)
+{
+	return pvcalls_front_sendmsg(sock, msg, len);
+}
+
+static int
+pvcalls_stream_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
+		     int flags)
+{
+	return pvcalls_front_recvmsg(sock, msg, len, flags);
+}
+
+static int pvcalls_release(struct socket *s)
+{
+	return pvcalls_front_release(s);
+}
+
+static int pvcalls_shutdown(struct socket *s, int h)
+{
+	return -ENOTSUPP;
+}
+
+static int sock_no_setsockopt(struct socket *sock, int level, int optname,
+			   sockptr_t optval, unsigned int optlen)
+{
+	return -ENOTSUPP;
+}
+
+static int sock_no_getsockopt(struct socket *sock, int level, int optname,
+			   char __user *optval, int __user *optlen)
+{
+	return -ENOTSUPP;
+}
+
+const struct proto_ops pvcalls_stream_ops = {
+	.family = PF_INET,
+	.owner = THIS_MODULE,
+	.release = pvcalls_release,
+	.bind = pvcalls_bind,
+	.connect = pvcalls_stream_connect,
+	.socketpair = sock_no_socketpair,
+	.accept = pvcalls_accept,
+	.getname = pvcalls_getname,
+	.poll = pvcalls_poll,
+	.ioctl = sock_no_ioctl,
+	.listen = pvcalls_listen,
+	.shutdown = pvcalls_shutdown,
+	.setsockopt = sock_no_setsockopt,
+	.getsockopt = sock_no_getsockopt,
+	.sendmsg = pvcalls_stream_sendmsg,
+	.recvmsg = pvcalls_stream_recvmsg,
+	.mmap = sock_no_mmap,
+	.sendpage = sock_no_sendpage,
+};
+
+bool pvcalls = false;
+static __init int xen_parse_pvcalls(char *arg)
+{
+       pvcalls = true;
+       return 0;
+}
+early_param("pvcalls", xen_parse_pvcalls);

include/xen/pvcalls.h

@@ -0,0 +1,13 @@
+#ifndef __LINUX_NET_PVCALLS_H
+#define __LINUX_NET_PVCALLS_H
+
+#include <linux/net.h>
+
+#ifdef CONFIG_XEN_PVCALLS_FRONTEND
+extern bool pvcalls;
+#else
+#define pvcalls (0)
+#endif
+extern const struct proto_ops pvcalls_stream_ops;
+
+#endif

net/ipv4/af_inet.c

@@ -120,6 +120,7 @@
 #include <net/compat.h>
 
 #include <trace/events/sock.h>
+#include <xen/pvcalls.h>
 
 /* The inetsw table contains everything that inet_create needs to
  * build a new socket.
@@ -1982,6 +1983,11 @@ static int __init inet_init(void)
 	for (r = &inetsw[0]; r < &inetsw[SOCK_MAX]; ++r)
 		INIT_LIST_HEAD(r);
 
+	if (pvcalls) {
+		pr_info("Enabling pvcalls for AF_INET SOCK_STREAM\n");
+		inetsw_array[0].ops = &pvcalls_stream_ops;
+	}
+
 	for (q = inetsw_array; q < &inetsw_array[INETSW_ARRAY_LEN]; ++q)
 		inet_register_protosw(q);