Re: [PATCH RFC 2/2] xen/kexec: Reserve KEXEC_TYPE_LIVEUPDATE and KEXEC_RANGE_MA_LIVEUPDATE

[Paul Durrant <xadimgnik@xxxxxxxxx>]

On 06/05/2021 11:42, Julien Grall wrote:
> From: Julien Grall <jgrall@xxxxxxxxxx>
>
> Unfortunately, the code to support Live Update has already been merged in
> Kexec and shipped since 2.0.21. Reserve the IDs used by Kexec before they
> end up to be re-used for a different purpose.
>
> This patch reserves two IDs:
>      * KEXEC_TYPE_LIVEUPDATE: New operation to request Live Update
>      * KEXEC_MA_RANGE_LIVEUPDATE: New range to query the Live Update
>        area below Xen
>
> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
Reviewed-by: Paul Durrant <paul@xxxxxxx>

> ---
>   xen/include/public/kexec.h | 13 ++++++++++---
>   1 file changed, 10 insertions(+), 3 deletions(-)
>
> diff --git a/xen/include/public/kexec.h b/xen/include/public/kexec.h
> index 3f2a118381ba..650d2feb036f 100644
> --- a/xen/include/public/kexec.h
> +++ b/xen/include/public/kexec.h
> @@ -71,17 +71,22 @@
>    */
>   
>   /*
> - * Kexec supports two types of operation:
> + * Kexec supports three types of operation:
>    * - kexec into a regular kernel, very similar to a standard reboot
>    *   - KEXEC_TYPE_DEFAULT is used to specify this type
>    * - kexec into a special "crash kernel", aka kexec-on-panic
>    *   - KEXEC_TYPE_CRASH is used to specify this type
>    *   - parts of our system may be broken at kexec-on-panic time
>    *     - the code should be kept as simple and self-contained as possible
> + * - Live update into a new Xen, preserving all running domains
> + *   - KEXEC_TYPE_LIVE_UPDATE is used to specify this type
> + *   - Xen performs non-cooperative live migration and stores live
> + *     update state in memory, passing it to the new Xen.
>    */
>   
> -#define KEXEC_TYPE_DEFAULT 0
> -#define KEXEC_TYPE_CRASH   1
> +#define KEXEC_TYPE_DEFAULT      0
> +#define KEXEC_TYPE_CRASH        1
> +#define KEXEC_TYPE_LIVEUPDATE   2
>   
>   
>   /* The kexec implementation for Xen allows the user to load two
> @@ -150,6 +155,8 @@ typedef struct xen_kexec_load_v1 {
>   #define KEXEC_RANGE_MA_EFI_MEMMAP 5 /* machine address and size of
>                                        * of the EFI Memory Map */
>   #define KEXEC_RANGE_MA_VMCOREINFO 6 /* machine address and size of vmcoreinfo 
> */
> +/* machine address and size of the Live Update area below Xen */
> +#define KEXEC_RANGE_MA_LIVEUPDATE 7
>   
>   /*
>    * Find the address and size of certain memory areas