Re: [KVM x86 vPMU Patch 2/2] KVM: x86/vPMU: Fix unnecessary signed extension for AMD PERFCTRn

[Andrew Jones]

On Fri, Aug 07, 2015 at 03:53:30PM -0400, Wei Huang wrote:
> According to AMD programmer's manual, AMD PERFCTRn is 64-bit MSR which,
> unlike Intel perf counters, doesn't require signed extension. This
> patch removes the unnecessary conversion in SVM vPMU code when PERFCTRn
> is being updated.
> 
> Signed-off-by: Wei Huang <wei@xxxxxxxxxx>
> ---
>  arch/x86/kvm/pmu_amd.c | 2 --
>  1 file changed, 2 deletions(-)
> 
> diff --git a/arch/x86/kvm/pmu_amd.c b/arch/x86/kvm/pmu_amd.c
> index 886aa25..39b9112 100644
> --- a/arch/x86/kvm/pmu_amd.c
> +++ b/arch/x86/kvm/pmu_amd.c
> @@ -133,8 +133,6 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
>  	/* MSR_K7_PERFCTRn */
>  	pmc = get_gp_pmc(pmu, msr, MSR_K7_PERFCTR0);
>  	if (pmc) {
> -		if (!msr_info->host_initiated)
> -			data = (s64)data;
>  		pmc->counter += data - pmc_read_counter(pmc);
>  		return 0;
>  	}
> -- 
> 1.8.3.1

Reviewed-by: Andrew Jones <drjones@xxxxxxxxxx>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/