linux-kernel - Re: [PATCH 1/2] KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in nested_vmcb_valid

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Date:   Wed, 11 Aug 2021 23:37:56 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     Emanuele Giuseppe Esposito <eesposit@...hat.com>,
        kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] KVM: nSVM: move nested_vmcb_check_cr3_cr4 logic in
 nested_vmcb_valid_sregs

On Mon, 2021-08-09 at 16:53 +0200, Emanuele Giuseppe Esposito wrote:
> nested_vmcb_check_cr3_cr4 is not called by anyone else, and removing the
> call simplifies next patch

Tiny nitpick: I would call this 'inline the nested_vmcb_check_cr3_cr4' instead of
move, but please feel free to ignore.

Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>



> 
> Signed-off-by: Emanuele Giuseppe Esposito <eesposit@...hat.com>
> ---
>  arch/x86/kvm/svm/nested.c | 35 +++++++++++++----------------------
>  1 file changed, 13 insertions(+), 22 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> index 5e13357da21e..0ac2d14add15 100644
> --- a/arch/x86/kvm/svm/nested.c
> +++ b/arch/x86/kvm/svm/nested.c
> @@ -257,27 +257,6 @@ static bool nested_vmcb_check_controls(struct kvm_vcpu *vcpu,
>  	return true;
>  }
>  
> -static bool nested_vmcb_check_cr3_cr4(struct kvm_vcpu *vcpu,
> -				      struct vmcb_save_area *save)
> -{
> -	/*
> -	 * These checks are also performed by KVM_SET_SREGS,
> -	 * except that EFER.LMA is not checked by SVM against
> -	 * CR0.PG && EFER.LME.
> -	 */
> -	if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) {
> -		if (CC(!(save->cr4 & X86_CR4_PAE)) ||
> -		    CC(!(save->cr0 & X86_CR0_PE)) ||
> -		    CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3)))
> -			return false;
> -	}
> -
> -	if (CC(!kvm_is_valid_cr4(vcpu, save->cr4)))
> -		return false;
> -
> -	return true;
> -}
> -
>  /* Common checks that apply to both L1 and L2 state.  */
>  static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
>  				    struct vmcb_save_area *save)
> @@ -299,7 +278,19 @@ static bool nested_vmcb_valid_sregs(struct kvm_vcpu *vcpu,
>  	if (CC(!kvm_dr6_valid(save->dr6)) || CC(!kvm_dr7_valid(save->dr7)))
>  		return false;
>  
> -	if (!nested_vmcb_check_cr3_cr4(vcpu, save))
> +	/*
> +	 * These checks are also performed by KVM_SET_SREGS,
> +	 * except that EFER.LMA is not checked by SVM against
> +	 * CR0.PG && EFER.LME.
> +	 */
> +	if ((save->efer & EFER_LME) && (save->cr0 & X86_CR0_PG)) {
> +		if (CC(!(save->cr4 & X86_CR4_PAE)) ||
> +		    CC(!(save->cr0 & X86_CR0_PE)) ||
> +		    CC(kvm_vcpu_is_illegal_gpa(vcpu, save->cr3)))
> +			return false;
> +	}
> +
> +	if (CC(!kvm_is_valid_cr4(vcpu, save->cr4)))
>  		return false;
>  
>  	if (CC(!kvm_valid_efer(vcpu, save->efer)))