linux-kernel - Re: [RFC 5/7] KVM: MMU: Add support for PKS emulation

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Date:   Wed, 27 Jan 2021 11:00:07 +0800
From:   Chenyi Qiang <chenyi.qiang@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Xiaoyao Li <xiaoyao.li@...el.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC 5/7] KVM: MMU: Add support for PKS emulation



On 1/27/2021 2:23 AM, Paolo Bonzini wrote:
> On 07/08/20 10:48, Chenyi Qiang wrote:
>>
>>          if (pte_access & PT_USER_MASK)
>>              pkr_bits = (vcpu->arch.pkru >> (pte_pkey * 2)) & 3;
>> +        else if (!kvm_get_msr(vcpu, MSR_IA32_PKRS, &pkrs))
>> +            pkr_bits = (pkrs >> (pte_pkey * 2)) & 3;
> 
> You should be able to always use vcpu->arch.pkrs here.  So
> 
> pkr = pte_access & PT_USER_MASK ? vcpu->arch.pkru : vcpu->arch.pkrs;
> pkr_bits = (pkr >> pte_pkey * 2) & 3;
> 
> Paolo

Concerning vcpu->arch.pkrs would be the only use case in current 
submitted patches, is it still necessary to shadow it?

>