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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v8 09/17] libxl_dm: Pre-open QMP socket for QEMU
This patch moves 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 useful to find out if QEMU is ready, and
pre-opening it means that libxl can connect to it without waiting for
QEMU to create it.
The pre-opening is conditional, 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.perard@xxxxxxxxxx>
Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
---
Notes:
v8:
acked
v7:
move domain_build_state init/dispose to a different patch
and close dm_monitor_fd in that new dispose function
assert that dm_monitor_fd should be -1 when using old qemu
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 | 5 +++
tools/libxl/libxl_dm.c | 71 ++++++++++++++++++++++++++++++++++--
tools/libxl/libxl_internal.h | 1 +
3 files changed, 73 insertions(+), 4 deletions(-)
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 4ca25f56a6..89f4766a27 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -763,12 +763,17 @@ static int store_libxl_entry(libxl__gc *gc, uint32_t
domid,
void libxl__domain_build_state_init(libxl__domain_build_state *state)
{
+ state->dm_monitor_fd = -1;
}
void libxl__domain_build_state_dispose(libxl__domain_build_state *state)
{
libxl__file_reference_unmap(&state->pv_kernel);
libxl__file_reference_unmap(&state->pv_ramdisk);
+ if (state->dm_monitor_fd >= 0) {
+ close(state->dm_monitor_fd);
+ state->dm_monitor_fd = -1;
+ }
}
/*----- main domain creation -----*/
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 200310083f..b9921eb885 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -670,6 +670,8 @@ static int libxl__build_device_model_args_old(libxl__gc *gc,
dm_args = flexarray_make(gc, 16, 1);
dm_envs = flexarray_make(gc, 16, 1);
+ assert(state->dm_monitor_fd == -1);
+
libxl__set_qemu_env_for_xsa_180(gc, dm_envs);
flexarray_vappend(dm_args, dm,
@@ -1100,6 +1102,51 @@ 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);
+
+ 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,
@@ -1132,10 +1179,16 @@ 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");
@@ -2437,6 +2490,16 @@ void libxl__spawn_local_dm(libxl__egc *egc,
libxl__dm_spawn_state *dmss)
if (rc)
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);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 88c01ff118..83bc384d3e 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1240,6 +1240,7 @@ 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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