Re: [Xen-devel] [PATCH v4 02/15] x86/cpu: Fix common cpuid faulting probing for AMD and Hygon

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 30.03.19 at 11:42, <puwen@xxxxxxxx> wrote:
> There is no MSR_INTEL_PLATFORM_INFO for AMD and Hygon families. So directly
> return false in the function probe_cpuid_faulting() if !cpu_has_hypervisor.

I think it would have been nice if you had mentioned the real
reason why you want to bypass the MSR accesses. This way it
sounds as if the change was only cosmetic, and hence could be
left out.

> Signed-off-by: Pu Wen <puwen@xxxxxxxx>

Acked-by: Jan Beulich <jbeulich@xxxxxxxx>

Andrew, I'd like to ask for explicit clarification that you don't object
to this adjustment. But if you do, please clarify why.

Thanks, Jan

> --- a/xen/arch/x86/cpu/common.c
> +++ b/xen/arch/x86/cpu/common.c
> @@ -116,6 +116,11 @@ bool __init probe_cpuid_faulting(void)
>       uint64_t val;
>       int rc;
>  
> +     if ((boot_cpu_data.x86_vendor == X86_VENDOR_HYGON ||
> +          boot_cpu_data.x86_vendor == X86_VENDOR_AMD) &&
> +         !cpu_has_hypervisor)
> +             return false;
> +
>       if ((rc = rdmsr_safe(MSR_INTEL_PLATFORM_INFO, val)) == 0)
>               raw_msr_policy.plaform_info.cpuid_faulting =
>                       val & MSR_PLATFORM_INFO_CPUID_FAULTING;
> -- 
> 2.7.4





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