This patch move the creation of the QMP unix socket from QEMU to libxl.
But libxl doesn't rely on this yet.
When starting QEMU with dm_restrict=1, pre-open the QMP socket before
exec QEMU. That socket will be usefull to findout if QEMU is ready, and
pre-opening it means that libxl can connect to it without waiting for
QEMU to create it.
The pre-openning is conditionnal, based on the use of dm_restrict
because it is using a new command line option of QEMU, and dm_restrict
support in QEMU is newer.
-chardev socket,fd=X is available with QEMU 2.12, since commit:
> char: allow passing pre-opened socket file descriptor at startup
> 0935700f8544033ebbd41e1f13cd528f8a58d24d
dm_restrict is available in QEMU 3.0.
Signed-off-by: Anthony PERARD <anthony.per...@citrix.com>
---
Notes:
v6:
move dm_monitor_fd into libxl_domain_build_info (or d_state)
-> move the creation of the socket into libxl__spawn_local_dm
instead of libxl__build_device_model_args
Use libxl_domid type instead of int for libxl__pre_open_qmp_socket()
Check function calls (bind and listen) return value in a separate
statement.
typo and other coding style issue fixes
v5:
use libxl__remove_file
few changes in coding style
remove stale includes (sys/socket, sys/un) which are now in
libxl_internal.h
v4:
separate the logic to open a socket into a function.
Use libxl__prepare_sockaddr_un() to check path size
tools/libxl/libxl_create.c | 3 ++
tools/libxl/libxl_dm.c | 71 ++++++++++++++++++++++++++++++++++--
tools/libxl/libxl_internal.h | 1 +
3 files changed, 71 insertions(+), 4 deletions(-)
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index fa573344bc..fcbe36feba 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -539,6 +539,9 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config
*d_config,
libxl_domain_create_info *info = &d_config->c_info;
libxl_domain_build_info *b_info = &d_config->b_info;
+ /* Attempt to initialise libxl__domain_build_state */
+ state->dm_monitor_fd = -1;
+
uuid_string = libxl__uuid2string(gc, info->uuid);
if (!uuid_string) {
rc = ERROR_NOMEM;
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 9c47060473..3bf1e37894 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -910,6 +910,53 @@ static char *qemu_disk_ide_drive_string(libxl__gc *gc,
const char *target_path,
return drive;
}
+static int libxl__pre_open_qmp_socket(libxl__gc *gc, libxl_domid domid,
+ int *fd_r)
+{
+ int rc, r;
+ int fd;
+ struct sockaddr_un un;
+ const char *path = libxl__qemu_qmp_path(gc, domid);
+
+ assert(fd_r != NULL);
+
+ fd = socket(AF_UNIX, SOCK_STREAM, 0);
+ if (fd < 0) {
+ LOGED(ERROR, domid, "socket() failed");
+ return ERROR_FAIL;
+ }
+
+ rc = libxl__prepare_sockaddr_un(gc, &un, path, "QEMU's QMP socket");
+ if (rc)
+ goto out;
+
+ rc = libxl__remove_file(gc, path);
+ if (rc)
+ goto out;
+
+ r = bind(fd, (struct sockaddr *) &un, sizeof(un));
+ if (r < 0) {
+ LOGED(ERROR, domid, "bind('%s') failed", path);
+ rc = ERROR_FAIL;
+ goto out;
+ }
+
+ r = listen(fd, 1);
+ if (r < 0) {
+ LOGED(ERROR, domid, "listen() failed");
+ rc = ERROR_FAIL;
+ goto out;
+ }
+
+ *fd_r = fd;
+ rc = 0;
+
+out:
+ if (rc && fd >= 0)
+ close(fd);
+ return rc;
+}
+
static int libxl__build_device_model_args_new(libxl__gc *gc,
const char *dm, int guest_domid,
const libxl_domain_config
*guest_config,
@@ -944,10 +991,16 @@ static int libxl__build_device_model_args_new(libxl__gc
*gc,
GCSPRINTF("%d", guest_domid), NULL);
flexarray_append(dm_args, "-chardev");
- flexarray_append(dm_args,
- GCSPRINTF("socket,id=libxl-cmd,"
- "path=%s,server,nowait",
- libxl__qemu_qmp_path(gc, guest_domid)));
+ if (state->dm_monitor_fd >= 0) {
+ flexarray_append(dm_args,
+ GCSPRINTF("socket,id=libxl-cmd,fd=%d,server,nowait",
+ state->dm_monitor_fd));
+ } else {
+ flexarray_append(dm_args,
+ GCSPRINTF("socket,id=libxl-cmd,"
+ "path=%s,server,nowait",
+ libxl__qemu_qmp_path(gc, guest_domid)));
+ }
flexarray_append(dm_args, "-no-shutdown");
flexarray_append(dm_args, "-mon");
@@ -2000,6 +2053,7 @@ void libxl__spawn_stub_dm(libxl__egc *egc,
libxl__stub_dm_spawn_state *sdss)
if (ret)
goto out;
+ d_state->dm_monitor_fd = -1;
ret = libxl__build_device_model_args(gc, "stubdom-dm", guest_domid,
guest_config, &args, NULL,
d_state, NULL);
@@ -2303,6 +2357,14 @@ void libxl__spawn_local_dm(libxl__egc *egc,
libxl__dm_spawn_state *dmss)
rc = ERROR_FAIL;
goto out;
}
+ if (b_info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN &&
+ libxl_defbool_val(b_info->dm_restrict)) {
+ /* If we have to use dm_restrict, QEMU needs to be new enough
+ * and will have the new interface where we can pre-open the
+ * QMP socket. */
+ rc = libxl__pre_open_qmp_socket(gc, domid, &state->dm_monitor_fd);
+ if (rc) goto out;
+ }
rc = libxl__build_device_model_args(gc, dm, domid, guest_config,
&args, &envs, state,
&dm_state_fd);
@@ -2408,6 +2470,7 @@ out_close:
if (logfile_w >= 0) close(logfile_w);
out:
if (dm_state_fd >= 0) close(dm_state_fd);
+ if (state->dm_monitor_fd >= 0) close(state->dm_monitor_fd);
if (rc)
device_model_spawn_outcome(egc, dmss, rc);
}
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 6c118ccb3b..b768d1b09f 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1233,6 +1233,7 @@ typedef struct {
char *console_tty;
char *saved_state;
+ int dm_monitor_fd;
libxl__file_reference pv_kernel;
libxl__file_reference pv_ramdisk;
--
Anthony PERARD
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