Re: [PATCH] xen/public: Correct the documentation of where the Xen cpuid leaves can be found

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 10/21/2014 03:21 PM, Andrew Cooper wrote:
> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> CC: Keir Fraser <keir@xen.org>
> CC: Jan Beulich <JBeulich@suse.com>
> CC: Tim Deegan <tim@xen.org>
> CC: Ian Campbell <Ian.Campbell@citrix.com>
> CC: Ian Jackson <Ian.Jackson@eu.citrix.com>

Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>

> ---
>   xen/include/public/arch-x86/cpuid.h |   18 +++++++++++++-----
>   1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/xen/include/public/arch-x86/cpuid.h b/xen/include/public/arch-x86/cpuid.h
> index e57a457..6005dfe 100644
> --- a/xen/include/public/arch-x86/cpuid.h
> +++ b/xen/include/public/arch-x86/cpuid.h
> @@ -30,12 +30,20 @@
>   #ifndef __XEN_PUBLIC_ARCH_X86_CPUID_H__
>   #define __XEN_PUBLIC_ARCH_X86_CPUID_H__
>   
> -/* Xen identification leaves start at 0x40000000. */
> +/*
> + * For compatibility with other hypervisor interfaces, the Xen cpuid leaves
> + * can be found at the first otherwise unused 0x100 aligned boundary starting
> + * from 0x40000000.
> + *
> + * e.g If viridian extensions are enabled for an HVM domain, the Xen cpuid
> + * leaves will start at 0x40000100
> + */
> +
>   #define XEN_CPUID_FIRST_LEAF 0x40000000
>   #define XEN_CPUID_LEAF(i)    (XEN_CPUID_FIRST_LEAF + (i))
>   
>   /*
> - * Leaf 1 (0x40000000)
> + * Leaf 1 (0x40000x00)
>    * EAX: Largest Xen-information leaf. All leaves up to an including @EAX
>    *      are supported by the Xen host.
>    * EBX-EDX: "XenVMMXenVMM" signature, allowing positive identification
> @@ -46,14 +54,14 @@
>   #define XEN_CPUID_SIGNATURE_EDX 0x4d4d566e /* "nVMM" */
>   
>   /*
> - * Leaf 2 (0x40000001)
> + * Leaf 2 (0x40000x01)
>    * EAX[31:16]: Xen major version.
>    * EAX[15: 0]: Xen minor version.
>    * EBX-EDX: Reserved (currently all zeroes).
>    */
>   
>   /*
> - * Leaf 3 (0x40000002)
> + * Leaf 3 (0x40000x02)
>    * EAX: Number of hypercall transfer pages. This register is always guaranteed
>    *      to specify one hypercall page.
>    * EBX: Base address of Xen-specific MSRs.
> @@ -66,7 +74,7 @@
>   #define XEN_CPUID_FEAT1_MMU_PT_UPDATE_PRESERVE_AD  (1u<<0)
>   
>   /*
> - * Leaf 5 (0x40000004)
> + * Leaf 5 (0x40000x04)
>    * HVM-specific features
>    */
>