Re: [PATCH v11 4/8] KVM: SVM: Move SEV-ES VMSA allocation to a dedicated sev_vcpu_create() helper

["Nikunj A. Dadhania" <nikunj@amd.com>]

On 8/20/2025 5:18 AM, Sean Christopherson wrote:
> Add a dedicated sev_vcpu_create() helper to allocate the VMSA page for
> SEV-ES+ vCPUs, and to allow for consolidating a variety of related SEV+
> code in the near future.
> 
> No functional change intended.
> 
> Signed-off-by: Sean Christopherson <seanjc@google.com>

Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>

> ---
>  arch/x86/kvm/svm/sev.c | 20 ++++++++++++++++++++
>  arch/x86/kvm/svm/svm.c | 25 +++++++------------------
>  arch/x86/kvm/svm/svm.h |  2 ++
>  3 files changed, 29 insertions(+), 18 deletions(-)
> 
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index e88dce598785..c17cc4eb0fe1 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -4561,6 +4561,26 @@ void sev_init_vmcb(struct vcpu_svm *svm)
>  		sev_es_init_vmcb(svm);
>  }
>  
> +int sev_vcpu_create(struct kvm_vcpu *vcpu)
> +{
> +	struct vcpu_svm *svm = to_svm(vcpu);
> +	struct page *vmsa_page;
> +
> +	if (!sev_es_guest(vcpu->kvm))
> +		return 0;
> +
> +	/*
> +	 * SEV-ES guests require a separate (from the VMCB) VMSA page used to
> +	 * contain the encrypted register state of the guest.
> +	 */
> +	vmsa_page = snp_safe_alloc_page();
> +	if (!vmsa_page)
> +		return -ENOMEM;
> +
> +	svm->sev_es.vmsa = page_address(vmsa_page);
> +	return 0;
> +}
> +
>  void sev_es_vcpu_reset(struct vcpu_svm *svm)
>  {
>  	struct kvm_vcpu *vcpu = &svm->vcpu;
> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
> index d9931c6c4bc6..3d4c14e0244f 100644
> --- a/arch/x86/kvm/svm/svm.c
> +++ b/arch/x86/kvm/svm/svm.c
> @@ -1275,7 +1275,6 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
>  {
>  	struct vcpu_svm *svm;
>  	struct page *vmcb01_page;
> -	struct page *vmsa_page = NULL;
>  	int err;
>  
>  	BUILD_BUG_ON(offsetof(struct vcpu_svm, vcpu) != 0);
> @@ -1286,24 +1285,18 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
>  	if (!vmcb01_page)
>  		goto out;
>  
> -	if (sev_es_guest(vcpu->kvm)) {
> -		/*
> -		 * SEV-ES guests require a separate VMSA page used to contain
> -		 * the encrypted register state of the guest.
> -		 */
> -		vmsa_page = snp_safe_alloc_page();
> -		if (!vmsa_page)
> -			goto error_free_vmcb_page;
> -	}
> +	err = sev_vcpu_create(vcpu);
> +	if (err)
> +		goto error_free_vmcb_page;
>  
>  	err = avic_init_vcpu(svm);
>  	if (err)
> -		goto error_free_vmsa_page;
> +		goto error_free_sev;
>  
>  	svm->msrpm = svm_vcpu_alloc_msrpm();
>  	if (!svm->msrpm) {
>  		err = -ENOMEM;
> -		goto error_free_vmsa_page;
> +		goto error_free_sev;
>  	}
>  
>  	svm->x2avic_msrs_intercepted = true;
> @@ -1312,16 +1305,12 @@ static int svm_vcpu_create(struct kvm_vcpu *vcpu)
>  	svm->vmcb01.pa = __sme_set(page_to_pfn(vmcb01_page) << PAGE_SHIFT);
>  	svm_switch_vmcb(svm, &svm->vmcb01);
>  
> -	if (vmsa_page)
> -		svm->sev_es.vmsa = page_address(vmsa_page);
> -
>  	svm->guest_state_loaded = false;
>  
>  	return 0;
>  
> -error_free_vmsa_page:
> -	if (vmsa_page)
> -		__free_page(vmsa_page);
> +error_free_sev:
> +	sev_free_vcpu(vcpu);
>  error_free_vmcb_page:
>  	__free_page(vmcb01_page);
>  out:
> diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
> index 58b9d168e0c8..cf2569b5451a 100644
> --- a/arch/x86/kvm/svm/svm.h
> +++ b/arch/x86/kvm/svm/svm.h
> @@ -854,6 +854,7 @@ static inline struct page *snp_safe_alloc_page(void)
>  	return snp_safe_alloc_page_node(numa_node_id(), GFP_KERNEL_ACCOUNT);
>  }
>  
> +int sev_vcpu_create(struct kvm_vcpu *vcpu);
>  void sev_free_vcpu(struct kvm_vcpu *vcpu);
>  void sev_vm_destroy(struct kvm *kvm);
>  void __init sev_set_cpu_caps(void);
> @@ -880,6 +881,7 @@ static inline struct page *snp_safe_alloc_page(void)
>  	return snp_safe_alloc_page_node(numa_node_id(), GFP_KERNEL_ACCOUNT);
>  }
>  
> +static inline int sev_vcpu_create(struct kvm_vcpu *vcpu) { return 0; }
>  static inline void sev_free_vcpu(struct kvm_vcpu *vcpu) {}
>  static inline void sev_vm_destroy(struct kvm *kvm) {}
>  static inline void __init sev_set_cpu_caps(void) {}