Re: [PATCH v5 COLOPre 08/18] tools/libxl: introduce libxl__domain_restore_device_model to load qemu state

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Dec 17, 2015 at 03:48:12PM +0800, Wen Congyang wrote:
> From: Yang Hongyang <hongyang.yang@easystack.cn>
> 
> In normal migration, the qemu state was passed to qemu as a parameter.

/was/is/

> With COLO, Secondary vm is running. So we will do the following steps
> at every checkpoint:
> 1. suspend both primary vm and secondary vm
> 2. sync the state
> 3. resume both primary vm and secondary vm
> Primary will send qemu's state in step2, and
> Secondary's qemu should read it and restore the state before it

s/Secondary/secondary/
> is resumed. We can not pass the state to qemu as a parameter because
> Secondary QEMU already started at this point, so we introduce

s/Secondary/secondary/
> libxl__domain_restore_device_model() to do it.
> This API should be called before resuming secondary vm.

s/before/MUST/

> 
> Signed-off-by: Yang Hongyang <hongyang.yang@easystack.cn>
> Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
> Cc: Anthony Perard <anthony.perard@citrix.com>
> ---
>  tools/libxl/libxl_dom_save.c | 20 ++++++++++++++++++++
>  tools/libxl/libxl_internal.h |  4 ++++
>  tools/libxl/libxl_qmp.c      | 10 ++++++++++
>  3 files changed, 34 insertions(+)
> 
> diff --git a/tools/libxl/libxl_dom_save.c b/tools/libxl/libxl_dom_save.c
> index 0bfa5fc..88cb1b3 100644
> --- a/tools/libxl/libxl_dom_save.c
> +++ b/tools/libxl/libxl_dom_save.c
> @@ -609,6 +609,26 @@ int libxl__restore_emulator_xenstore_data(libxl__domain_create_state *dcs,
>      return rc;
>  }
>  
> +int libxl__domain_restore_device_model(libxl__gc *gc, uint32_t domid,
> +                                       const char *restore_file)
> +{
> +    int rc;
> +
> +    switch (libxl__device_model_version_running(gc, domid)) {
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN_TRADITIONAL:
> +        /* not supported now */

Perhaps: Will never be supported.

> +        rc = ERROR_INVAL;
> +        break;
> +    case LIBXL_DEVICE_MODEL_VERSION_QEMU_XEN:
> +        rc = libxl__qmp_restore(gc, domid, restore_file);
> +        break;
> +    default:
> +        rc = ERROR_INVAL;
> +    }
> +
> +    return rc;
> +}
> +