linux-kernel - Re: [PATCH 4/9] KVM: SVM: Open code handling of unexpected exits in svm_invoke_exit

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Message-ID: <4ct4nu4fepnzasoix6ougoyid6r7e7dcxamdvncbmlw5sgcpna@6hja4h67q6ce>
Date: Thu, 13 Nov 2025 23:33:58 +0000
From: Yosry Ahmed <yosry.ahmed@...ux.dev>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>, 
	Vitaly Kuznetsov <vkuznets@...hat.com>, "K. Y. Srinivasan" <kys@...rosoft.com>, 
	Haiyang Zhang <haiyangz@...rosoft.com>, Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>, 
	kvm@...r.kernel.org, linux-hyperv@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Jim Mattson <jmattson@...gle.com>
Subject: Re: [PATCH 4/9] KVM: SVM: Open code handling of unexpected exits in
 svm_invoke_exit_handler()

On Thu, Nov 13, 2025 at 02:56:16PM -0800, Sean Christopherson wrote:
> Fold svm_check_exit_valid() and svm_handle_invalid_exit() into their sole
> caller, svm_invoke_exit_handler(), as having tiny single-use helpers makes
> the code unncessarily difficult to follow.  This will also allow for
> additional cleanups in svm_invoke_exit_handler().
> 
> No functional change intended.
> 
> Suggested-by: Yosry Ahmed <yosry.ahmed@...ux.dev>
> Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Yosry Ahmed <yosry.ahmed@...ux.dev>

> ---
>  arch/x86/kvm/svm/svm.c | 25 ++++++++++---------------
>  1 file changed, 10 insertions(+), 15 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index 52b759408853..638a67ef0c37 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -3433,23 +3433,13 @@ static void dump_vmcb(struct kvm_vcpu *vcpu)
>  		sev_free_decrypted_vmsa(vcpu, save);
>  }
>  
> -static bool svm_check_exit_valid(u64 exit_code)
> -{
> -	return (exit_code < ARRAY_SIZE(svm_exit_handlers) &&
> -		svm_exit_handlers[exit_code]);
> -}
> -
> -static int svm_handle_invalid_exit(struct kvm_vcpu *vcpu, u64 exit_code)
> -{
> -	dump_vmcb(vcpu);
> -	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
> -	return 0;
> -}
> -
>  int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code)
>  {
> -	if (!svm_check_exit_valid(exit_code))
> -		return svm_handle_invalid_exit(vcpu, exit_code);
> +	if (exit_code >= ARRAY_SIZE(svm_exit_handlers))
> +		goto unexpected_vmexit;
> +
> +	if (!svm_exit_handlers[exit_code])
> +		goto unexpected_vmexit;
>  
>  #ifdef CONFIG_MITIGATION_RETPOLINE
>  	if (exit_code == SVM_EXIT_MSR)
> @@ -3468,6 +3458,11 @@ int svm_invoke_exit_handler(struct kvm_vcpu *vcpu, u64 exit_code)
>  #endif
>  #endif
>  	return svm_exit_handlers[exit_code](vcpu);
> +
> +unexpected_vmexit:
> +	dump_vmcb(vcpu);
> +	kvm_prepare_unexpected_reason_exit(vcpu, exit_code);
> +	return 0;
>  }
>  
>  static void svm_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
> -- 
> 2.52.0.rc1.455.g30608eb744-goog
>