linux-kernel - Re: [PATCH 2/2] KVM: SVM: Add support for MPK feature on AMD

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Date:   Thu, 7 May 2020 10:07:46 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Babu Moger <babu.moger@....com>
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Subject: Re: [PATCH 2/2] KVM: SVM: Add support for MPK feature on AMD

On 07/05/20 00:26, Sean Christopherson wrote:
>> +	/* Load the guest pkru state */
>> +	if (static_cpu_has(X86_FEATURE_PKU) &&
>> +	    kvm_read_cr4_bits(vcpu, X86_CR4_PKE) &&
>> +	    vcpu->arch.pkru != svm->host_pkru)
>> +		__write_pkru(vcpu->arch.pkru);
> This and the restoration should be moved to common x86 helpers, at a glance
> they look identical.
> 
> In short, pretty much all of this belongs in common x86.
> 

We could stick this in kvm_load_guest_xsave_state
kvm_load_host_xsave_state.  It's not a perfect match, after all the code
itself proves that PKRU can be loaded without XSAVE; but it's close
enough and it's exactly in the right point of vmx_vcpu_run and svm_vcpu_run.

Paolo