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. Move also initialization for device_model_stubdomain to the new function. 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@aepfle.de> Cc: Roger Pau Monné <roger.pau@citrix.com> Cc: Anthony PERARD <anthony.perard@citrix.com> --- tools/libxl/libxl_create.c | 99 ++++++++++++++++++++++++++--------------- 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, 75 insertions(+), 37 deletions(-) diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c index XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_create.c +++ b/tools/libxl/libxl_create.c @@ -XXX,XX +XXX,XX @@ #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; + + libxl_defbool_setdefault(&b_info->device_model_stubdomain, false); + + 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) { @@ -XXX,XX +XXX,XX @@ int libxl__domain_build_info_setdefault(libxl__gc *gc, return rc; } - libxl_defbool_setdefault(&b_info->device_model_stubdomain, false); - if (libxl_defbool_val(b_info->device_model_stubdomain) && !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"); @@ -XXX,XX +XXX,XX @@ 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 XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_dm.c +++ b/tools/libxl/libxl_dm.c @@ -XXX,XX +XXX,XX @@ 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 XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_dom_suspend.c +++ b/tools/libxl/libxl_dom_suspend.c @@ -XXX,XX +XXX,XX @@ 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; @@ -XXX,XX +XXX,XX @@ 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 XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -XXX,XX +XXX,XX @@ _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 XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_types.idl +++ b/tools/libxl/libxl_types.idl @@ -XXX,XX +XXX,XX @@ 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", [ _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel 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() used to hardcode 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. Introduce LIBXL_DEVICE_MODEL_VERSION_NONE for PV and PVH that have no need for a device_model to make the state explicit. Indicate this new state via LIBXL_HAVE macro in libxl.h. v05: - move initialization of device_model_version to extra commit - return error from libxl__need_xenpv_qemu - add LIBXL_HAVE_DEVICE_MODEL_VERSION_NONE v04: - make sure device_model_stubdomain is initialized 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@aepfle.de> Cc: Roger Pau Monné <roger.pau@citrix.com> Cc: Anthony PERARD <anthony.perard@citrix.com> --- tools/libxl/libxl.h | 7 +++++++ tools/libxl/libxl_create.c | 17 ++++++++++++++--- tools/libxl/libxl_dom_suspend.c | 8 ++++++-- tools/libxl/libxl_types.idl | 1 + 4 files changed, 28 insertions(+), 5 deletions(-) diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h index XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl.h +++ b/tools/libxl/libxl.h @@ -XXX,XX +XXX,XX @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, const libxl_mac *src); */ #define LIBXL_HAVE_PVCALLS 1 +/* + * LIBXL_HAVE_DEVICE_MODEL_VERSION_NONE + * + * If this is defined, libxl will only run a device-model if required. + */ +#define LIBXL_HAVE_DEVICE_MODEL_VERSION_NONE 1 + typedef char **libxl_string_list; void libxl_string_list_dispose(libxl_string_list *sl); int libxl_string_list_length(const libxl_string_list *sl); diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c index XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_create.c +++ b/tools/libxl/libxl_create.c @@ -XXX,XX +XXX,XX @@ int libxl__domain_set_device_model(libxl__gc *gc, libxl_domain_config *d_config) } break; default: - b_info->device_model_version = - LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL; - break; + 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; + break; + default: + LOGE(ERROR, "Unable to determine QEMU requisite"); + return ret; + } } if (b_info->device_model_version == LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN) { diff --git a/tools/libxl/libxl_dom_suspend.c b/tools/libxl/libxl_dom_suspend.c index XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_dom_suspend.c +++ b/tools/libxl/libxl_dom_suspend.c @@ -XXX,XX +XXX,XX @@ 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; @@ -XXX,XX +XXX,XX @@ 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_types.idl b/tools/libxl/libxl_types.idl index XXXXXXX..XXXXXXX 100644 --- a/tools/libxl/libxl_types.idl +++ b/tools/libxl/libxl_types.idl @@ -XXX,XX +XXX,XX @@ 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"), ]) libxl_console_type = Enumeration("console_type", [ _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel