From mboxrd@z Thu Jan  1 00:00:00 1970
From: Avi Kivity <avi@redhat.com>
Subject: Re: [PATCH 1/6] KVM: SVM: Implement infrastructure for TSC_RATE_MSR
Date: Thu, 24 Mar 2011 11:51:59 +0200
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References: <1300952424-32014-1-git-send-email-joerg.roedel@amd.com> <1300952424-32014-2-git-send-email-joerg.roedel@amd.com>
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Cc: Marcelo Tosatti <mtosatti@redhat.com>,
	Zachary Amsden <zamsden@redhat.com>, kvm@vger.kernel.org
To: Joerg Roedel <joerg.roedel@amd.com>
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On 03/24/2011 09:40 AM, Joerg Roedel wrote:
> This patch enhances the kvm_amd module with functions to
> support the TSC_RATE_MSR which can be used to set a given
> tsc frequency for the guest vcpu.
>
>
> @@ -1141,6 +1175,9 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
>
>   	for (i = 0; i<  NR_HOST_SAVE_USER_MSRS; i++)
>   		rdmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
> +
> +	if (static_cpu_has(X86_FEATURE_TSCRATEMSR)&&  svm->tsc_scale.enabled)
> +		wrmsrl(MSR_AMD64_TSC_RATIO, svm->tsc_scale.ratio);
>   }
>
>   static void svm_vcpu_put(struct kvm_vcpu *vcpu)
> @@ -1161,6 +1198,9 @@ static void svm_vcpu_put(struct kvm_vcpu *vcpu)
>   #endif
>   	for (i = 0; i<  NR_HOST_SAVE_USER_MSRS; i++)
>   		wrmsrl(host_save_user_msrs[i], svm->host_user_msrs[i]);
> +
> +	if (static_cpu_has(X86_FEATURE_TSCRATEMSR)&&  svm->tsc_scale.enabled)
> +		wrmsr(MSR_AMD64_TSC_RATIO, 0, 1);
>   }

This is a bit suboptimal.  We could do something like

static DEFINE_PER_CPU(u64, current_tsc_scale);

   static void svm_vcpu_load(...)
   {
       ...
       if (svm->tsc_scale != __get_cpu_var(current_tsc_scale)) {
           __get_cpu_var(current_tsc_scale) = svm->tsc_scale;
           wrmsrl(MSR_AMD64_TSC_RATIO, svm->tsc_scale);
       }
   }

with no changes to svm_vcpu_put() (note no tsc_scale.enabled either, 
just put the unity value for disabled).

-- 
error compiling committee.c: too many arguments to function