linux-kernel - Re: [PATCH 06/43] KVM: x86: Properly reset MMU context at vCPU RESET/INIT

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Message-ID: <CAAeT=FzS0bP_7_wz6G6cL8-7pudTD7fhavLCVsOE0KnPXf99dQ@mail.gmail.com>
Date:   Mon, 17 May 2021 09:57:58 -0700
From:   Reiji Watanabe <reijiw@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 06/43] KVM: x86: Properly reset MMU context at vCPU RESET/INIT

>  void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>  {
> +       unsigned long old_cr0 = kvm_read_cr0(vcpu);
> +       unsigned long old_cr4 = kvm_read_cr4(vcpu);
> +
>         kvm_lapic_reset(vcpu, init_event);
>
>         vcpu->arch.hflags = 0;
> @@ -10483,6 +10485,10 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
>         vcpu->arch.ia32_xss = 0;
>
>         static_call(kvm_x86_vcpu_reset)(vcpu, init_event);
> +
> +       if (kvm_cr0_mmu_role_changed(old_cr0, kvm_read_cr0(vcpu)) ||
> +           kvm_cr4_mmu_role_changed(old_cr4, kvm_read_cr4(vcpu)))
> +               kvm_mmu_reset_context(vcpu);
>  }

I'm wondering if kvm_vcpu_reset() should call kvm_mmu_reset_context()
for a change in EFER.NX as well.

Thanks,
Reiji