Re: [PATCH v1 COLO Pre 04/12] tools/libxl: introduce a new API libxl__domain_restore() to load qemu state

[Wen Congyang <wency@cn.fujitsu.com>]

On 06/02/2015 05:26 PM, Yang Hongyang wrote:
> Secondary vm is running in colo mode. So we will do
> the following things again and again:
> 1. suspend both primay vm and secondary vm
> 2. sync the state
> 3. resume both primary vm and secondary vm
> We will send qemu's state each time in step2, and
> slave's qemu should read it each time before resuming
> secondary vm. Introduce a new API libxl__domain_restore()
> to do it. This API should be called before resuming
> secondary vm.
> 
> Signed-off-by: Yang Hongyang <yanghy@cn.fujitsu.com>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> ---
>  tools/libxl/Makefile            |  3 +-
>  tools/libxl/libxl_dom_restore.c | 76 +++++++++++++++++++++++++++++++++++++++++
>  tools/libxl/libxl_internal.h    |  4 +++
>  tools/libxl/libxl_qmp.c         | 10 ++++++
>  4 files changed, 92 insertions(+), 1 deletion(-)
>  create mode 100644 tools/libxl/libxl_dom_restore.c
> 
> diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
> index a87ee04..39ce836 100644
> --- a/tools/libxl/Makefile
> +++ b/tools/libxl/Makefile
> @@ -96,7 +96,8 @@ LIBXL_OBJS = flexarray.o libxl.o libxl_create.o libxl_dm.o libxl_pci.o \
>  			libxl_json.o libxl_aoutils.o libxl_numa.o libxl_vnuma.o \
>  			libxl_save_callout.o _libxl_save_msgs_callout.o \
>  			libxl_qmp.o libxl_event.o libxl_fork.o libxl_dom_suspend.o \
> -			libxl_toolstack.o libxl_dom_save.o $(LIBXL_OBJS-y)
> +			libxl_toolstack.o libxl_dom_save.o libxl_dom_restore.o \
> +			$(LIBXL_OBJS-y)
>  LIBXL_OBJS += libxl_genid.o
>  LIBXL_OBJS += _libxl_types.o libxl_flask.o _libxl_types_internal.o
>  
> diff --git a/tools/libxl/libxl_dom_restore.c b/tools/libxl/libxl_dom_restore.c
> new file mode 100644
> index 0000000..df15ece
> --- /dev/null
> +++ b/tools/libxl/libxl_dom_restore.c
> @@ -0,0 +1,76 @@
> +/*
> + * Copyright (C) 2015 FUJITSU LIMITED
> + * Author Yang Hongyang <yanghy@cn.fujitsu.com>
> + *        Wen congyang <wency@cn.fujitsu.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU Lesser General Public License as published
> + * by the Free Software Foundation; version 2 and later. with the special
> + * exception on linking described in file LICENSE.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU Lesser General Public License for more details.
> + */
> +
> +#include "libxl_osdeps.h" /* must come before any other headers */
> +
> +#include "libxl_internal.h"
> +
> +/*----- main code for restoring, in order of execution -----*/
> +
> +int libxl__domain_restore(libxl__gc *gc, uint32_t domid)
> +{
> +    int rc = 0;
> +
> +    libxl_domain_type type = libxl__domain_type(gc, domid);
> +    if (type != LIBXL_DOMAIN_TYPE_HVM) {
> +        rc = ERROR_FAIL;
> +        goto out;
> +    }
> +
> +    rc = libxl__domain_restore_device_model(gc, domid);
> +    if (rc)
> +        LOG(ERROR, "failed to restore device mode for domain %u:%d",
> +            domid, rc);
> +out:
> +    return rc;
> +}
> +
> +int libxl__domain_restore_device_model(libxl__gc *gc, uint32_t domid)
> +{
> +    char *state_file;
> +    int rc;
> +
> +    switch (libxl__device_model_version_running(gc, domid)) {
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
> +        /* not supported now */
> +        rc = ERROR_INVAL;
> +        break;
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
> +        /*
> +         * This function may be called too many times for the same gc,
> +         * so we use NOGC, and free the memory before return to avoid
> +         * OOM.
> +         */
> +        state_file = libxl__sprintf(NOGC,
> +                                    XC_DEVICE_MODEL_RESTORE_FILE".%d",
> +                                    domid);
> +        rc = libxl__qmp_restore(gc, domid, state_file);
> +        free(state_file);
> +        break;
> +    default:
> +        rc = ERROR_INVAL;
> +    }
> +
> +    return rc;
> +}
> +
> +/*
> + * Local variables:
> + * mode: C
> + * c-basic-offset: 4
> + * indent-tabs-mode: nil
> + * End:
> + */
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index 4bab0de..71728ff 100644
> --- a/tools/libxl/libxl_internal.h
> +++ b/tools/libxl/libxl_internal.h
> @@ -1022,6 +1022,7 @@ _hidden int libxl__domain_rename(libxl__gc *gc, uint32_t domid,
>  
>  _hidden int libxl__toolstack_restore(uint32_t domid, const uint8_t *buf,
>                                       uint32_t size, void *data);
> +_hidden int libxl__domain_restore_device_model(libxl__gc *gc, uint32_t domid);
>  _hidden int libxl__domain_resume_device_model(libxl__gc *gc, uint32_t domid);
>  
>  _hidden const char *libxl__userdata_path(libxl__gc *gc, uint32_t domid,
> @@ -1039,6 +1040,7 @@ _hidden int libxl__userdata_store(libxl__gc *gc, uint32_t domid,
>                                    const char *userdata_userid,
>                                    const uint8_t *data, int datalen);
>  
> +_hidden int libxl__domain_restore(libxl__gc *gc, uint32_t domid);
>  _hidden int libxl__domain_resume(libxl__gc *gc, uint32_t domid,
>                                   int suspend_cancel);
>  
> @@ -1650,6 +1652,8 @@ _hidden int libxl__qmp_stop(libxl__gc *gc, int domid);
>  _hidden int libxl__qmp_resume(libxl__gc *gc, int domid);
>  /* Save current QEMU state into fd. */
>  _hidden int libxl__qmp_save(libxl__gc *gc, int domid, const char *filename);
> +/* Load current QEMU state from fd. */
> +_hidden int libxl__qmp_restore(libxl__gc *gc, int domid, const char *filename);
>  /* Set dirty bitmap logging status */
>  _hidden int libxl__qmp_set_global_dirty_log(libxl__gc *gc, int domid, bool enable);
>  _hidden int libxl__qmp_insert_cdrom(libxl__gc *gc, int domid, const libxl_device_disk *disk);
> diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c
> index 9aa7e2e..a6f1a21 100644
> --- a/tools/libxl/libxl_qmp.c
> +++ b/tools/libxl/libxl_qmp.c
> @@ -892,6 +892,16 @@ int libxl__qmp_save(libxl__gc *gc, int domid, const char *filename)
>                             NULL, NULL);
>  }
>  
> +int libxl__qmp_restore(libxl__gc *gc, int domid, const char *state_file)
> +{
> +    libxl__json_object *args = NULL;
> +
> +    qmp_parameters_add_string(gc, &args, "filename", state_file);
> +
> +    return qmp_run_command(gc, domid, "xen-load-devices-state", args,
> +                           NULL, NULL);

IIRC, this is a new qmp command. Post the patch for qemu together?

Thanks
Wen Congyang

> +}
> +
>  static int qmp_change(libxl__gc *gc, libxl__qmp_handler *qmp,
>                        char *device, char *target, char *arg)
>  {
>