Re: [PATCH v2 3/4] KVM: arm64: Factor out pKVM hyp vcpu creation to separate function

[Quentin Perret <qperret@google.com>]

On Wednesday 26 Feb 2025 at 21:55:19 (+0000), Fuad Tabba wrote:
>  static int __pkvm_create_hyp_vm(struct kvm *host_kvm)
>  {
> -	size_t pgd_sz, hyp_vm_sz, hyp_vcpu_sz;
> +	size_t pgd_sz, hyp_vm_sz;
>  	struct kvm_vcpu *host_vcpu;
> -	pkvm_handle_t handle;
>  	void *pgd, *hyp_vm;
>  	unsigned long idx;
>  	int ret;
> @@ -161,33 +178,12 @@ static int __pkvm_create_hyp_vm(struct kvm *host_kvm)
>  	if (ret < 0)
>  		goto free_vm;
>  
> -	handle = ret;
> +	WRITE_ONCE(host_kvm->arch.pkvm.handle, ret);

What's the reason to make this a WRITE_ONCE? Does it mean we should
update the readers to be READ_ONCE()?

> -	host_kvm->arch.pkvm.handle = handle;
> -
> -	/* Donate memory for the vcpus at hyp and initialize it. */
> -	hyp_vcpu_sz = PAGE_ALIGN(PKVM_HYP_VCPU_SIZE);
>  	kvm_for_each_vcpu(idx, host_vcpu, host_kvm) {
> -		void *hyp_vcpu;
> -
> -		/* Indexing of the vcpus to be sequential starting at 0. */
> -		if (WARN_ON(host_vcpu->vcpu_idx != idx)) {
> -			ret = -EINVAL;
> -			goto destroy_vm;
> -		}
> -
> -		hyp_vcpu = alloc_pages_exact(hyp_vcpu_sz, GFP_KERNEL_ACCOUNT);
> -		if (!hyp_vcpu) {
> -			ret = -ENOMEM;
> -			goto destroy_vm;
> -		}
> -
> -		ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, host_vcpu,
> -					hyp_vcpu);
> -		if (ret) {
> -			free_pages_exact(hyp_vcpu, hyp_vcpu_sz);
> +		ret = __pkvm_create_hyp_vcpu(host_vcpu);
> +		if (ret)
>  			goto destroy_vm;
> -		}
>  	}
>  
>  	return 0;
> -- 
> 2.48.1.711.g2feabab25a-goog
>