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Date: Wed, 21 Dec 2011 13:45:09 +0200
From: Avi Kivity <avi@redhat.com>
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To: Jan Kiszka <jan.kiszka@siemens.com>
CC: Linus Torvalds <torvalds@linux-foundation.org>,
        Alexey Zaytsev <alexey.zaytsev@gmail.com>,
        "Liu, Jinsong" <jinsong.liu@intel.com>,
        Kernel development list <linux-kernel@vger.kernel.org>,
        Marcelo Tosatti <mtosatti@redhat.com>,
        "Garrett D'Amore" <garrett@nexenta.com>, kvm <kvm@vger.kernel.org>
Subject: Re: [PATCH v2] KVM: x86: Prevent exposing TSC deadline timer feature
 in the absence of in-kernel APIC
References: <CAB9v_DFOm8eDwR5YsqLfUEtr0ku2Zp=NCOaEjkSmxJFcpQ9nPA@mail.gmail.com> <BC00F5384FCFC9499AF06F92E8B78A9E287D8A556C@shsmsx502.ccr.corp.intel.com> <CAB9v_DFs_Rz04+waeBpVoJsLX+Ao7vQ4EtH2TJsX6jHZewWLQA@mail.gmail.com> <CAB9v_DEz44d54tZMyFenNoNNyu3LSA6dw31S_G8MaWp7UbAULQ@mail.gmail.com> <BC00F5384FCFC9499AF06F92E8B78A9E289048778E@shsmsx502.ccr.corp.intel.com> <CAB9v_DFL9K+hSum4k_TJBBP4jcenFiqggyzNNk3QHiPhkiqtxA@mail.gmail.com> <BC00F5384FCFC9499AF06F92E8B78A9E28904877AE@shsmsx502.ccr.corp.intel.com> <CAB9v_DEA4HJ2Xyc_fMrZ9gi9oNmKPTmG5LLCiwgsPDHbhgRaQw@mail.gmail.com> <CA+55aFwZ02yUBbUjJYuXjZnKcQRHC7uT9T1dckZQNSaC6SdnvA@mail.gmail.com> <4EF1146D.208@siemens.com> <4EF1B081.3010109@siemens.com> <4EF1B423.8050707@siemens.com> <4EF1B67D.7010603@redhat.com> <4EF1B7C0.3080200@siemens.com> <4EF1B8A4.2050008@redhat.com> <4EF1C2DD.8070303@siemens.com>
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On 12/21/2011 01:28 PM, Jan Kiszka wrote:
> > 
> > timer_mode_mask can just be slaved to the bit (as received by
> > KVM_SET_CPUID); that's exactly kvm_update_cpuid()'s role.
>
> Like

Ugh, the facebook generation invades lkml.

> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
> index 230f713..89b02bf 100644
> --- a/arch/x86/kvm/cpuid.c
> +++ b/arch/x86/kvm/cpuid.c
> @@ -27,7 +27,6 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpuid_entry2 *best;
>  	struct kvm_lapic *apic = vcpu->arch.apic;
> -	u32 timer_mode_mask;
>
>  	best = kvm_find_cpuid_entry(vcpu, 1, 0);
>  	if (!best)
> @@ -40,15 +39,12 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
>  			best->ecx |= bit(X86_FEATURE_OSXSAVE);
>  	}
>
> -	if (boot_cpu_data.x86_vendor == X86_VENDOR_INTEL &&
> -		best->function == 0x1) {
> -		best->ecx |= bit(X86_FEATURE_TSC_DEADLINE_TIMER);
> -		timer_mode_mask = 3 << 17;
> -	} else
> -		timer_mode_mask = 1 << 17;
> -
> -	if (apic)
> -		apic->lapic_timer.timer_mode_mask = timer_mode_mask;
> +	if (apic) {
> +		if (best->ecx & bit(X86_FEATURE_TSC_DEADLINE_TIMER))
> +			apic->lapic_timer.timer_mode_mask = 3 << 17;
> +		else
> +			apic->lapic_timer.timer_mode_mask = 1 << 17;
> +	}
>
>  	kvm_pmu_cpuid_update(vcpu);
>  }
>
>
> + the KVM_CAP thing?
>

+1

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