linux-kernel - Re: [PATCH 4/6] KVM: SEV: use mutex guard in sev_mem_enc_unregister

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Message-ID: <0f56dfe8-f343-4d43-8695-48222d8e3707@amd.com>
Date: Tue, 30 Dec 2025 15:18:52 +0100
From: "Gupta, Pankaj" <pankaj.gupta@....com>
To: Carlos López <clopez@...e.de>, kvm@...r.kernel.org,
 seanjc@...gle.com, pbonzini@...hat.com
Cc: tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/6] KVM: SEV: use mutex guard in
 sev_mem_enc_unregister_region()


On 12/19/2025 12:41 PM, Carlos López wrote:
> Simplify the error paths in sev_mem_enc_unregister_region() by using a
> mutex guard, allowing early return instead of using gotos.
>
> Signed-off-by: Carlos López <clopez@...e.de>

Reviewed-by: Pankaj Gupta <pankaj.gupta@....com>

> ---
>   arch/x86/kvm/svm/sev.c | 20 +++++---------------
>   1 file changed, 5 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 253f2ae24bfc..47ff5267ab01 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -2746,35 +2746,25 @@ int sev_mem_enc_unregister_region(struct kvm *kvm,
>   				  struct kvm_enc_region *range)
>   {
>   	struct enc_region *region;
> -	int ret;
>   
>   	/* If kvm is mirroring encryption context it isn't responsible for it */
>   	if (is_mirroring_enc_context(kvm))
>   		return -EINVAL;
>   
> -	mutex_lock(&kvm->lock);
> +	guard(mutex)(&kvm->lock);
>   
> -	if (!sev_guest(kvm)) {
> -		ret = -ENOTTY;
> -		goto failed;
> -	}
> +	if (!sev_guest(kvm))
> +		return -ENOTTY;
>   
>   	region = find_enc_region(kvm, range);
> -	if (!region) {
> -		ret = -EINVAL;
> -		goto failed;
> -	}
> +	if (!region)
> +		return -EINVAL;
>   
>   	sev_writeback_caches(kvm);
>   
>   	__unregister_enc_region_locked(kvm, region);
>   
> -	mutex_unlock(&kvm->lock);
>   	return 0;
> -
> -failed:
> -	mutex_unlock(&kvm->lock);
> -	return ret;
>   }
>   
>   int sev_vm_copy_enc_context_from(struct kvm *kvm, unsigned int source_fd)