Re: [Xen-devel] [PATCH v2 COLOPre 05/13] tools/libxl: introduce a new API libxl__domain_restore() to load qemu state

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Mon, 2015-06-08 at 11:43 +0800, 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.

Is this a preexisting qemu interface or one to be added?

> 
> Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
> Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
> ---
>  tools/libxl/libxl_dom_save.c | 47 
> ++++++++++++++++++++++++++++++++++++++++++++
>  tools/libxl/libxl_internal.h |  4 ++++
>  tools/libxl/libxl_qmp.c      | 10 ++++++++++
>  3 files changed, 61 insertions(+)
> 
> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c
> index 74a6bae..f9627f8 100644
> --- a/tools/libxl/libxl_dom_save.c
> +++ b/tools/libxl/libxl_dom_save.c
> @@ -663,6 +663,53 @@ int libxl__toolstack_restore(uint32_t domid, const 
> uint8_t *buf,
>      return 0;
>  }
>  
> +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
> diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
> index 1905195..20364c6 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);
>  _hidden int libxl__domain_s3_resume(libxl__gc *gc, int domid);
> @@ -1651,6 +1653,8 @@ _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);
> +}
> +
>  static int qmp_change(libxl__gc *gc, libxl__qmp_handler *qmp,
>                        char *device, char *target, char *arg)
>  {



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