Re: [PATCH v10 08/11] docs / tools: specify migration v4 to include DOMAIN_CONTEXT

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 08/10/2020 19:57, Paul Durrant wrote:
> diff --git a/docs/specs/libxc-migration-stream.pandoc 
> b/docs/specs/libxc-migration-stream.pandoc
> index 8aeab3b11b..aa6fe284f3 100644
> --- a/docs/specs/libxc-migration-stream.pandoc
> +++ b/docs/specs/libxc-migration-stream.pandoc
> @@ -127,7 +127,7 @@ marker      0xFFFFFFFFFFFFFFFF.
>  
>  id          0x58454E46 ("XENF" in ASCII).
>  
> -version     0x00000003.  The version of this specification.
> +version     0x00000004.  The version of this specification.
>  
>  options     bit 0: Endianness.  0 = little-endian, 1 = big-endian.
>  
> @@ -209,9 +209,9 @@ type         0x00000000: END
>  
>               0x00000006: X86_PV_VCPU_XSAVE
>  
> -             0x00000007: SHARED_INFO
> +             0x00000007: SHARED_INFO (deprecated)

"in v4" ?

> @@ -442,10 +444,11 @@ X86_PV_VCPU_MSRS             
> XEN_DOMCTL_{get,set}\_vcpu_msrs
>  
>  \clearpage
>  
> -SHARED_INFO
> ------------
> +SHARED_INFO (deprecated)
> +------------------------
>  
> -The content of the Shared Info page.
> +The content of the Shared Info page. This is incorporated into the
> +DOMAIN_CONTEXT record as of specification version 4.

This needs to be stricter.  A SHARED_INFO frame must not be present in a
v4 stream.

Absolutely nothing good can come from having the state twice.  Moreover, ...

>  
>       0     1     2     3     4     5     6     7 octet
>      +-------------------------------------------------+
> @@ -462,11 +465,12 @@ shared_info      Contents of the shared info page.  
> This record
>  
>  \clearpage
>  
> -X86_TSC_INFO
> -------------
> +X86_TSC_INFO (deprecated)
> +-------------------------
>  
>  Domain TSC information, as accessed by the
> -XEN_DOMCTL_{get,set}tscinfo hypercall sub-ops.
> +XEN_DOMCTL_{get,set}tscinfo hypercall sub-ops. This is incorporated into the
> +DOMAIN_CONTEXT record as of specification version 4.

... it is actively problematic for this one, as incarnation counts the
number of set_tsc_info() hypercalls.

~Andrew