linux-kernel - Re: [PATCH v7 7/8] KVM: VMX: Expose PKS to guest

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Date:   Fri, 27 May 2022 17:42:04 +0800
From:   "Wang, Lei" <lei4.wang@...el.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     pbonzini@...hat.com, vkuznets@...hat.com, wanpengli@...cent.com,
        jmattson@...gle.com, joro@...tes.org, chenyi.qiang@...el.com,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 7/8] KVM: VMX: Expose PKS to guest

On 5/25/2022 7:34 AM, Sean Christopherson wrote:
> On Sun, Apr 24, 2022, Lei Wang wrote:
>> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
>> index 9d0588e85410..cbcb0d7b47a4 100644
>> --- a/arch/x86/kvm/vmx/vmx.c
>> +++ b/arch/x86/kvm/vmx/vmx.c
>> @@ -3250,7 +3250,7 @@ void vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
>>   		}
>>   
>>   		/*
>> -		 * SMEP/SMAP/PKU is disabled if CPU is in non-paging mode in
>> +		 * SMEP/SMAP/PKU/PKS is disabled if CPU is in non-paging mode in
>>   		 * hardware.  To emulate this behavior, SMEP/SMAP/PKU needs
> Heh, missed one ;-)  Let's reduce future pain and reword this whole comment:
>
> 		/*
> 		 * SMEP/SMAP/PKU/PKS are effectively disabled if the CPU is in
> 		 * non-paging mode in hardware.  To emulate this behavior,
> 		 * clear them in the hardware CR4 when the guest switches to
> 		 * non-paging mode and unrestricted guest is disabled, as KVM
> 		 * must run the guest with hardware CR0.PG=1.
> 		 */
>
Nice catch, will fix it ;-)