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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v3] libxl: fix migration of PV and PVH domUs with and without qemu
If a domU has a qemu-xen instance attached, it is required to call qemus
"xen-save-devices-state" method. Without it, the receiving side of a PV or
PVH migration may be unable to lock the image:
xen be: qdisk-51712: xen be: qdisk-51712: error: Failed to get "write" lock
error: Failed to get "write" lock
xen be: qdisk-51712: xen be: qdisk-51712: initialise() failed
initialise() failed
To fix this bug, libxl__domain_suspend_device_model() and
libxl__domain_resume_device_model() have to be called not only for HVM,
but also if the active device_model is QEMU_XEN.
Unfortunately, libxl__domain_build_info_setdefault() hardcodes
b_info->device_model_version to QEMU_XEN if it does not know it any
better. As a result libxl__device_model_version_running() will return
incorrect values. This breaks domUs without a device_model.
libxl__qmp_stop() would wait 10 seconds in qmp_open() for a qemu that
will never appear. During this long timeframe the domU remains in state
paused on the sending side. As a result network connections may be
dropped. Once this bug is fixed as well, by just removing the assumption
that every domU has a QEMU_XEN, there is no code to actually initialise
b_info->device_model_version.
There is a helper function libxl__need_xenpv_qemu(), which is used in
various places to decide if a device_model has to be spawned. This
function can not be used as is, just to fill device_model_version,
because store_libxl_entry() was already called earlier.
Create a new function to set device_model_version. Move existing code
from libxl__domain_build_info_setdefault() to cover the HVM case. Add
new code to cover non-HVM case, use libxl__need_xenpv_qemu() to set
device_model_version.
Update libxl__spawn_stub_dm() and initiate_domain_create() to call the
new function prior libxl__domain_build_info_setdefault() because
device_mode_version is expected to be initialzed.
libxl_domain_need_memory() needs no update because it does not have a
d_config available anyway, and the callers provide a populated b_info.
Introduce LIBXL_DEVICE_MODEL_VERSION_NONE_REQUIRED for PV and PVH that
have no need for a device_model to make the state explicit.
v03:
- rearrange code to make sure device_model_version is initialized before
store_libxl_entry() is called
v02:
- update wording in a comment
- remove stale goto in domcreate_launch_dm
- initialize ret in libxl__need_xenpv_qemu
Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>
Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
---
v3 not runtime tested
tools/libxl/libxl_create.c | 95 +++++++++++++++++++++++++++--------------
tools/libxl/libxl_dm.c | 2 +
tools/libxl/libxl_dom_suspend.c | 8 +++-
tools/libxl/libxl_internal.h | 2 +
tools/libxl/libxl_types.idl | 1 +
5 files changed, 73 insertions(+), 35 deletions(-)
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index 89fe80fc9c..73ee66a67e 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -27,6 +27,62 @@
#include <xen-xsm/flask/flask.h>
+int libxl__domain_set_device_model(libxl__gc *gc, libxl_domain_config
*d_config)
+{
+ libxl_domain_build_info *b_info = &d_config->b_info;
+ int ret;
+
+ if (b_info->device_model_version)
+ return 0;
+
+ switch (b_info->type) {
+ case LIBXL_DOMAIN_TYPE_HVM:
+ if (libxl_defbool_val(b_info->device_model_stubdomain)) {
+ b_info->device_model_version =
+ LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+ } else {
+ b_info->device_model_version = libxl__default_device_model(gc);
+ }
+ break;
+ default:
+ ret = libxl__need_xenpv_qemu(gc, d_config);
+ switch (ret) {
+ case 1:
+ d_config->b_info.device_model_version =
+ LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
+ break;
+ case 0:
+ d_config->b_info.device_model_version =
+ LIBXL_DEVICE_MODEL_VERSION_NONE_REQUIRED;
+ break;
+ default:
+ LOGE(ERROR, "Unable to determine QEMU requisite");
+ return ERROR_FAIL;
+ }
+ }
+
+ if (b_info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
+ const char *dm;
+
+ dm = libxl__domain_device_model(gc, b_info);
+ ret = access(dm, X_OK);
+ if (ret < 0) {
+ /* qemu-xen unavailable, use qemu-xen-traditional */
+ if (errno == ENOENT) {
+ LOGE(INFO, "qemu-xen is unavailable"
+ ", using qemu-xen-traditional instead");
+ b_info->device_model_version =
+ LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
+ } else {
+ LOGE(ERROR, "qemu-xen access error");
+ return ERROR_FAIL;
+ }
+ }
+ }
+
+ return 0;
+}
+
int libxl__domain_create_info_setdefault(libxl__gc *gc,
libxl_domain_create_info *c_info)
{
@@ -86,39 +142,6 @@ int libxl__domain_build_info_setdefault(libxl__gc *gc,
!b_info->device_model_ssidref)
b_info->device_model_ssidref = SECINITSID_DOMDM;
- if (!b_info->device_model_version) {
- if (b_info->type == LIBXL_DOMAIN_TYPE_HVM) {
- if (libxl_defbool_val(b_info->device_model_stubdomain)) {
- b_info->device_model_version =
- LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
- } else {
- b_info->device_model_version = libxl__default_device_model(gc);
- }
- } else {
- b_info->device_model_version =
- LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN;
- }
- if (b_info->device_model_version
- == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
- const char *dm;
-
- dm = libxl__domain_device_model(gc, b_info);
- rc = access(dm, X_OK);
- if (rc < 0) {
- /* qemu-xen unavailable, use qemu-xen-traditional */
- if (errno == ENOENT) {
- LOGE(INFO, "qemu-xen is unavailable"
- ", using qemu-xen-traditional instead");
- b_info->device_model_version =
- LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL;
- } else {
- LOGE(ERROR, "qemu-xen access error");
- return ERROR_FAIL;
- }
- }
- }
- }
-
if (b_info->blkdev_start == NULL)
b_info->blkdev_start = libxl__strdup(NOGC, "xvda");
@@ -938,6 +961,12 @@ static void initiate_domain_create(libxl__egc *egc,
goto error_out;
}
+ ret = libxl__domain_set_device_model(gc, d_config);
+ if (ret) {
+ LOGD(ERROR, domid, "Unable to set domain device model");
+ goto error_out;
+ }
+
ret = libxl__domain_create_info_setdefault(gc, &d_config->c_info);
if (ret) {
LOGD(ERROR, domid, "Unable to set domain create info defaults");
diff --git a/tools/libxl/libxl_dm.c b/tools/libxl/libxl_dm.c
index 2f19786bdd..086e566311 100644
--- a/tools/libxl/libxl_dm.c
+++ b/tools/libxl/libxl_dm.c
@@ -2168,6 +2168,8 @@ void libxl__spawn_stub_dm(libxl__egc *egc,
libxl__stub_dm_spawn_state *sdss)
dm_config->c_info.run_hotplug_scripts =
guest_config->c_info.run_hotplug_scripts;
+ ret = libxl__domain_set_device_model(gc, dm_config);
+ if (ret) goto out;
ret = libxl__domain_create_info_setdefault(gc, &dm_config->c_info);
if (ret) goto out;
ret = libxl__domain_build_info_setdefault(gc, &dm_config->b_info);
diff --git a/tools/libxl/libxl_dom_suspend.c b/tools/libxl/libxl_dom_suspend.c
index d1af3a6573..c492fe5dd1 100644
--- a/tools/libxl/libxl_dom_suspend.c
+++ b/tools/libxl/libxl_dom_suspend.c
@@ -379,7 +379,9 @@ static void
domain_suspend_common_guest_suspended(libxl__egc *egc,
libxl__ev_xswatch_deregister(gc, &dsps->guest_watch);
libxl__ev_time_deregister(gc, &dsps->guest_timeout);
- if (dsps->type == LIBXL_DOMAIN_TYPE_HVM) {
+ if (dsps->type == LIBXL_DOMAIN_TYPE_HVM ||
+ libxl__device_model_version_running(gc, dsps->domid) ==
+ LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
dsps->callback_device_model_done = domain_suspend_common_done;
libxl__domain_suspend_device_model(egc, dsps); /* must be last */
return;
@@ -459,7 +461,9 @@ int libxl__domain_resume(libxl__gc *gc, uint32_t domid, int
suspend_cancel)
goto out;
}
- if (type == LIBXL_DOMAIN_TYPE_HVM) {
+ if (type == LIBXL_DOMAIN_TYPE_HVM ||
+ libxl__device_model_version_running(gc, domid) ==
+ LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) {
rc = libxl__domain_resume_device_model(gc, domid);
if (rc) {
LOGD(ERROR, domid, "failed to resume device model:%d", rc);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 44e0221284..25f113404b 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -1374,6 +1374,8 @@ _hidden int libxl__device_nextid(libxl__gc *gc, uint32_t
domid,
_hidden int libxl__resolve_domid(libxl__gc *gc, const char *name,
uint32_t *domid);
+_hidden int libxl__domain_set_device_model(libxl__gc *gc,
+ libxl_domain_config *d_config);
/*
* For each aggregate type which can be used as an input we provide:
*
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index cb4702fd7a..7d75bd3850 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -106,6 +106,7 @@ libxl_device_model_version =
Enumeration("device_model_version", [
(0, "UNKNOWN"),
(1, "QEMU_XEN_TRADITIONAL"), # Historical qemu-xen device model (qemu-dm)
(2, "QEMU_XEN"), # Upstream based qemu-xen device model
+ (3, "NONE_REQUIRED"),
])
libxl_console_type = Enumeration("console_type", [
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