Re: [PATCH 0 of 2] Support for Paging/Sharing on AMD

[Tim Deegan <tim@xen.org>]

Hi, 

> diff -r 5a7e18e57c72 -r 228f7aebb0ff xen/arch/x86/mm/mem_event.c
> --- a/xen/arch/x86/mm/mem_event.c
> +++ b/xen/arch/x86/mm/mem_event.c
> @@ -563,8 +563,11 @@ int mem_event_domctl(struct domain *d, x
>              if ( !hap_enabled(d) )
>                  break;
> 
> -            /* Currently only EPT is supported */
> -            if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL )
> +            /* Currently EPT or AMD with no iommu/hap page table sharing are
> +             * supported. Further, AMD considered experimental atm. */
> +            if ( !((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) ||
> +                   ((boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
> +                     !iommu_use_hap_pt(d))) )

I think we can just drop the test for Intelness rather than adding one
for AMDness.  hap_enabled() above is good enough to avoid Cyrix &c. :)
Also, I think the cset I just checked in to interlock IOMMU vs
sharing/paging should be enough that we don't need the
!iommu_use_hap_pt(d) test either (or is there some concern about the 
pagetable layout?) 

That is, can we just drop this whole test?

The right place to mark it experimental is in the user docs and example
config files. 

Cheers,

Tim.