[PATCH 10/10] TCP based live migration

Anthony Liguori
2008-09-09T19:51:01Z

This patch introduces a tcp protocol for live migration. It can be used as
follows:

qemu-system-x86_64 -hda ~/images/linux-test.img -monitor stdio
<vm runs for a while>
(qemu) migrate tcp:localhost:1025

On the same system:

qemu-system-x86_64 -hda ~/images/linux-test.img -incoming tcp:localhost:1025

The monitor can be interacted with while waiting for an incoming live migration.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/Makefile.target b/Makefile.target
index 6bf5229..0fa585c 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -473,7 +473,7 @@ endif #CONFIG_DARWIN_USER
ifndef CONFIG_USER_ONLY

OBJS=vl.o osdep.o monitor.o pci.o loader.o isa_mmio.o machine.o net-checksum.o
-OBJS+=migration.o
+OBJS+=migration.o migration-tcp.o
ifdef CONFIG_WIN32
OBJS+=block-raw-win32.o
else
diff --git a/migration-tcp.c b/migration-tcp.c
new file mode 100644
index 0000000..6b46bd4
--- /dev/null
+++ b/migration-tcp.c
@@ -0,0 +1,243 @@
+#include "qemu-common.h"
+#include "qemu_socket.h"
+#include "migration.h"
+#include "qemu-char.h"
+#include "sysemu.h"
+#include "console.h"
+
+/* FIXME resume monitor on error */
+
+
+typedef struct FdMigrationState
+{
+ QEMUFile *file;
+ int64_t bandwidth_limit;
+ int fd;
+} FdMigrationState;
+
+static void fd_put_notify(void *opaque)
+{
+ FdMigrationState *s = opaque;
+
+ qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
+ qemu_file_put_notify(s->file);
+}
+
+static ssize_t fd_put_buffer(void *opaque, const void *data, size_t size)
+{
+ FdMigrationState *s = opaque;
+ ssize_t ret;
+
+ do {
+ ret = write(s->fd, data, size);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret == -1)
+ ret = -errno;
+
+ if (ret == -EAGAIN)
+ qemu_set_fd_handler2(s->fd, NULL, NULL, fd_put_notify, s);
+
+ return ret;
+}
+
+static int fd_close(void *opaque)
+{
+ FdMigrationState *s = opaque;
+ return close(s->fd);
+}
+
+static void fd_wait_for_unfreeze(void *opaque)
+{
+ FdMigrationState *s = opaque;
+ int ret;
+
+ do {
+ fd_set wfds;
+
+ FD_ZERO(&wfds);
+ FD_SET(s->fd, &wfds);
+
+ ret = select(s->fd + 1, NULL, &wfds, NULL, NULL);
+ } while (ret == -1 && errno == EINTR);
+}
+
+static void fd_put_ready(void *opaque)
+{
+ FdMigrationState *s = opaque;
+
+ if (qemu_savevm_state_iterate(s->file) == 1) {
+ vm_stop(0);
+ qemu_savevm_state_complete(s->file);
+ qemu_fclose(s->file);
+ qemu_free(s);
+ monitor_resume();
+ }
+}
+
+static void tcp_connect_migrate(FdMigrationState *s)
+{
+ int ret;
+
+ s->file = qemu_fopen_ops_buffered(s,
+ s->bandwidth_limit,
+ fd_put_buffer,
+ fd_put_ready,
+ fd_wait_for_unfreeze,
+ fd_close);
+
+ ret = qemu_savevm_state_begin(s->file);
+ if (ret < 0) {
+ fprintf(stderr, "savevm failed %d\n", ret);
+ return;
+ }
+
+ monitor_suspend();
+
+ fd_put_ready(s);
+}
+
+static void tcp_wait_for_connect(void *opaque)
+{
+ FdMigrationState *s = opaque;
+ int val, ret;
+ int valsize = sizeof(val);
+
+ do {
+ ret = getsockopt(s->fd, SOL_SOCKET, SO_ERROR, &val, &valsize);
+ } while (ret == -1 && errno == EINTR);
+
+ if (ret < 0) {
+ fprintf(stderr, "Could not query connect success\n");
+ return;
+ }
+
+ qemu_set_fd_handler2(s->fd, NULL, NULL, NULL, NULL);
+
+ if (val == 0)
+ tcp_connect_migrate(s);
+ else {
+ fprintf(stderr, "failed to connect to host\n");
+ close(s->fd);
+ qemu_free(s);
+ }
+}
+
+int tcp_start_outgoing_migration(const char *host_port, int64_t bandwidth_limit)
+{
+ struct sockaddr_in addr;
+ FdMigrationState *s;
+ int ret;
+
+ if (parse_host_port(&addr, host_port) < 0) {
+ fprintf(stderr, "invalid host/port combination: %s\n", host_port);
+ return -EINVAL;
+ }
+
+ s = qemu_mallocz(sizeof(*s));
+ if (s == NULL)
+ return -ENOMEM;
+
+ s->bandwidth_limit = bandwidth_limit;
+ s->fd = socket(PF_INET, SOCK_STREAM, 0);
+ if (s->fd == -1) {
+ qemu_free(s);
+ return -errno;
+ }
+
+ fcntl(s->fd, F_SETFL, O_NONBLOCK);
+
+ do {
+ ret = connect(s->fd, (struct sockaddr *)&addr, sizeof(addr));
+ if (ret == -1)
+ ret = -errno;
+
+ if (ret == -EINPROGRESS)
+ qemu_set_fd_handler2(s->fd, NULL, NULL, tcp_wait_for_connect, s);
+ } while (ret == -EINTR);
+
+ if (ret < 0 && ret != -EINPROGRESS) {
+ fprintf(stderr, "failed to connect to host\n");
+ close(s->fd);
+ qemu_free(s);
+ } else if (ret >= 0)
+ tcp_connect_migrate(s);
+
+ return 0;
+}
+
+static void tcp_accept_incoming_migration(void *opaque)
+{
+ struct sockaddr_in addr;
+ socklen_t addrlen = sizeof(addr);
+ int s = (unsigned long)opaque;
+ QEMUFile *f;
+ int c, ret;
+
+ do {
+ c = accept(s, (struct sockaddr *)&addr, &addrlen);
+ } while (c == -1 && errno == EINTR);
+
+ if (c == -1) {
+ fprintf(stderr, "could not accept migration connection\n");
+ return;
+ }
+
+ f = qemu_fopen_fd(c);
+ if (f == NULL) {
+ fprintf(stderr, "could not qemu_fopen socket\n");
+ goto out;
+ }
+
+ vm_stop(0); /* just in case */
+ ret = qemu_loadvm_state(f);
+ if (ret < 0) {
+ fprintf(stderr, "load of migration failed\n");
+ goto out_fopen;
+ }
+
+ /* we've successfully migrated, close the server socket */
+ qemu_set_fd_handler2(s, NULL, NULL, NULL, NULL);
+ close(s);
+
+ vm_start();
+
+out_fopen:
+ qemu_fclose(f);
+out:
+ close(c);
+}
+
+int tcp_start_incoming_migration(const char *host_port)
+{
+ struct sockaddr_in addr;
+ int val;
+ int s;
+
+ if (parse_host_port(&addr, host_port) < 0) {
+ fprintf(stderr, "invalid host/port combination: %s\n", host_port);
+ return -EINVAL;
+ }
+
+ s = socket(PF_INET, SOCK_STREAM, 0);
+ if (s == -1)
+ return -errno;
+
+ val = 1;
+ setsockopt(s, SOL_SOCKET, SO_REUSEADDR, (const char *)&val, sizeof(val));
+
+ if (bind(s, (struct sockaddr *)&addr, sizeof(addr)) == -1)
+ goto err;
+
+ if (listen(s, 1) == -1)
+ goto err;
+
+ qemu_set_fd_handler2(s, NULL, tcp_accept_incoming_migration, NULL,
+ (void *)(unsigned long)s);
+
+ return 0;
+
+err:
+ close(s);
+ return -errno;
+}
diff --git a/migration.c b/migration.c
index 8a8b4a5..6023e02 100644
--- a/migration.c
+++ b/migration.c
@@ -200,10 +200,20 @@ QEMUFile *qemu_fopen_ops_buffered(void *opaque,

void qemu_start_incoming_migration(const char *uri)
{
- fprintf(stderr, "unknown migration protocol: %s\n", uri);
+ const char *p;
+
+ if (strstart(uri, "tcp:", &p))
+ tcp_start_incoming_migration(p);
+ else
+ fprintf(stderr, "unknown migration protocol: %s\n", uri);
}

void do_migrate(const char *uri)
{
- fprintf(stderr, "unknown migration protocol: %s\n", uri);
+ const char *p;
+
+ if (strstart(uri, "tcp:", &p))
+ tcp_start_outgoing_migration(p, 20 << 20);
+ else
+ fprintf(stderr, "unknown migration protocol: %s\n", uri);
}
diff --git a/migration.h b/migration.h
index 2119a59..314cc87 100644
--- a/migration.h
+++ b/migration.h
@@ -18,4 +18,8 @@ void qemu_start_incoming_migration(const char *uri);

void do_migrate(const char *uri);

+int tcp_start_incoming_migration(const char *host_port);
+
+int tcp_start_outgoing_migration(const char *host_port, int64_t bandwidth_limit);
+
#endif