Re: [XEN PATCH] x86/msr: Allow hardware domain to read package C-state residency counters

[Jan Beulich]

On 18.07.2023 15:17, Simon Gaiser wrote:
> --- a/xen/arch/x86/pv/emul-priv-op.c
> +++ b/xen/arch/x86/pv/emul-priv-op.c
> @@ -965,6 +965,20 @@ static int cf_check read_msr(
>          *val = 0;
>          return X86EMUL_OKAY;
>  
> +    case MSR_PKG_C2_RESIDENCY:
> +    case MSR_PKG_C3_RESIDENCY:
> +    case MSR_PKG_C6_RESIDENCY:
> +    case MSR_PKG_C7_RESIDENCY:
> +    case MSR_PKG_C8_RESIDENCY:
> +    case MSR_PKG_C9_RESIDENCY:
> +    case MSR_PKG_C10_RESIDENCY:
> +        if ( boot_cpu_data.x86_vendor != X86_VENDOR_INTEL )
> +            break;
> +        if ( is_hardware_domain(currd) )
> +            goto normal;
> +        *val = 0;
> +        return X86EMUL_OKAY;

In addition to what Andrew said: Why would we suddenly allow these
reads to succeed for DomU-s?

Jan