KVM: arm64: Factor out pKVM hyp vcpu creation to separate function

Move the code that creates and initializes the hyp view of a vcpu
in pKVM to its own function. This is meant to make the transition
to initializing every vcpu individually clearer.

Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20250314111832.4137161-4-tabba@google.com
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: Fuad Tabba

arch/arm64/kvm/pkvm.c

@@ -114,6 +114,26 @@ static void __pkvm_destroy_hyp_vm(struct kvm *host_kvm)
 	free_hyp_memcache(&host_kvm->arch.pkvm.stage2_teardown_mc);
 }
 
+static int __pkvm_create_hyp_vcpu(struct kvm_vcpu *vcpu)
+{
+	size_t hyp_vcpu_sz = PAGE_ALIGN(PKVM_HYP_VCPU_SIZE);
+	pkvm_handle_t handle = vcpu->kvm->arch.pkvm.handle;
+	void *hyp_vcpu;
+	int ret;
+
+	vcpu->arch.pkvm_memcache.flags |= HYP_MEMCACHE_ACCOUNT_STAGE2;
+
+	hyp_vcpu = alloc_pages_exact(hyp_vcpu_sz, GFP_KERNEL_ACCOUNT);
+	if (!hyp_vcpu)
+		return -ENOMEM;
+
+	ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, vcpu, hyp_vcpu);
+	if (ret)
+		free_pages_exact(hyp_vcpu, hyp_vcpu_sz);
+
+	return ret;
+}
+
 /*
  * Allocates and donates memory for hypervisor VM structs at EL2.
  *
@@ -126,9 +146,8 @@ static void __pkvm_destroy_hyp_vm(struct kvm *host_kvm)
  */
 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;
@@ -162,37 +181,14 @@ static int __pkvm_create_hyp_vm(struct kvm *host_kvm)
 	if (ret < 0)
 		goto free_vm;
 
-	handle = ret;
-
-	host_kvm->arch.pkvm.handle = handle;
+	host_kvm->arch.pkvm.handle = ret;
 	host_kvm->arch.pkvm.stage2_teardown_mc.flags |= HYP_MEMCACHE_ACCOUNT_STAGE2;
 	kvm_account_pgtable_pages(pgd, pgd_sz / PAGE_SIZE);
 
-	/* 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;
-
-		host_vcpu->arch.pkvm_memcache.flags |= HYP_MEMCACHE_ACCOUNT_STAGE2;
-
-		/* 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;