Re: [PATCH 2/4] KVM: SVM: use NPT page attributes

From	Xiao Guangrong <guangrong.xiao@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/4] KVM: SVM: use NPT page attributes
Date	2015-07-10 03:30 +0200
Message-ID	<pKvix-7Kt-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <pJBq1-6gd-5@gated-at.bofh.it> <pJQIq-7xL-9@gated-at.bofh.it> <pJVI7-24h-31@gated-at.bofh.it> <pK9UJ-2Sw-5@gated-at.bofh.it> <pKlMd-1Mu-1@gated-at.bofh.it>
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On 07/09/2015 11:18 PM, Paolo Bonzini wrote:
>
>
> On 09/07/2015 04:30, Xiao Guangrong wrote:
>>>>> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
>>>>> index 602b974a60a6..0f125c1860ec 100644
>>>>> --- a/arch/x86/kvm/svm.c
>>>>> +++ b/arch/x86/kvm/svm.c
>>>>> @@ -1085,6 +1085,47 @@ static u64 svm_compute_tsc_offset(struct
>>>>> kvm_vcpu *vcpu, u64 target_tsc)
>>>>>         return target_tsc - tsc;
>>>>>     }
>>>>>
>>>>> +static void svm_set_guest_pat(struct vcpu_svm *svm, u64 *g_pat)
>>>>> +{
>>>>> +    struct kvm_vcpu *vcpu = &svm->vcpu;
>>>>> +
>>>>> +    /* Unlike Intel, AMD takes the guest's CR0.CD into account.
>>>>
>>>> I noticed this code in svm_set_cr0():
>>>>
>>>>       if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_CD_NW_CLEARED))
>>>>           cr0 &= ~(X86_CR0_CD | X86_CR0_NW);
>>>>
>>>> gCR0.CD is hidden to CPU if KVM_QUIRK_CD_NW_CLEARED is not set and looks
>>>> like it is the normal case after grepping Qemu code.
>
> Hi Xiao,
>
> yes, this is correct.  QEMU still does not have support for disabling
> "quirks", so gCR0.CD is currently hidden on SVM.  I would like to
> include this series in 4.2, while for 4.3 I will disable the quirk above
> altogether (it is superseded by the way PAT is forced to all-WB).
>

That plan sounds good to me.

You will drop disabled_quirks completely or just enable it in Qemu? :)
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Re: [PATCH 2/4] KVM: SVM: use NPT page attributes Xiao Guangrong <guangrong.xiao@linux.intel.com> - 2015-07-10 03:30 +0200

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