linux-kernel - Re: [PATCH 1/4] KVM: x86: mark synthetic SMM vmexit as SVM_EXIT

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Message-ID: <Yh5KTtLhRyfmx/ZF@google.com>
Date:   Tue, 1 Mar 2022 16:31:10 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Maxim Levitsky <mlevitsk@...hat.com>
Cc:     kvm@...r.kernel.org, Jim Mattson <jmattson@...gle.com>,
        "H. Peter Anvin" <hpa@...or.com>, linux-kernel@...r.kernel.org,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Borislav Petkov <bp@...en8.de>, x86@...nel.org
Subject: Re: [PATCH 1/4] KVM: x86: mark synthetic SMM vmexit as SVM_EXIT_SW

On Tue, Mar 01, 2022, Maxim Levitsky wrote:
> Use a dummy unused vmexit reason to mark the 'VM exit' that is happening
> when kvm exits to handle SMM, which is not a real VM exit.

Why not use "62h VMEXIT_SMI"?

> This makes it a bit easier to read the KVM trace, and avoids
> other potential problems.

What other potential problems?

> Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
> ---
>  arch/x86/kvm/svm/svm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 7038c76fa8410..c08fd7f4f3414 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -4218,7 +4218,7 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
>  	svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
>  	svm->vmcb->save.rip = vcpu->arch.regs[VCPU_REGS_RIP];
>  
> -	ret = nested_svm_vmexit(svm);
> +	ret = nested_svm_simple_vmexit(svm, SVM_EXIT_SW);
>  	if (ret)
>  		return ret;
>  
> -- 
> 2.26.3
>