[PATCH v10 54/59] KVM: arm64: nv: Allocate VNCR page when required

[Marc Zyngier]

If running a NV guest on an ARMv8.4-NV capable system, let's
allocate an additional page that will be used by the hypervisor
to fulfill system register accesses.

Signed-off-by: Marc Zyngier <maz at kernel.org>
---
 arch/arm64/kvm/nested.c | 10 ++++++++++
 arch/arm64/kvm/reset.c  |  1 +
 2 files changed, 11 insertions(+)

diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
index f41a86f0e924..bc47c79afad0 100644
--- a/arch/arm64/kvm/nested.c
+++ b/arch/arm64/kvm/nested.c
@@ -38,6 +38,14 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu)
 	if (!cpus_have_final_cap(ARM64_HAS_NESTED_VIRT))
 		return -EINVAL;
 
+	if (cpus_have_final_cap(ARM64_HAS_ENHANCED_NESTED_VIRT)) {
+		if (!vcpu->arch.ctxt.vncr_array)
+			vcpu->arch.ctxt.vncr_array = (u64 *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+
+		if (!vcpu->arch.ctxt.vncr_array)
+			return -ENOMEM;
+	}
+
 	mutex_lock(&kvm->arch.config_lock);
 
 	/*
@@ -67,6 +75,8 @@ int kvm_vcpu_init_nested(struct kvm_vcpu *vcpu)
 		    kvm_init_stage2_mmu(kvm, &tmp[num_mmus - 2], 0)) {
 			kvm_free_stage2_pgd(&tmp[num_mmus - 1]);
 			kvm_free_stage2_pgd(&tmp[num_mmus - 2]);
+			free_page((unsigned long)vcpu->arch.ctxt.vncr_array);
+			vcpu->arch.ctxt.vncr_array = NULL;
 		} else {
 			kvm->arch.nested_mmus_size = num_mmus;
 			ret = 0;
diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
index ad11cc514b3d..d35b6a50a03a 100644
--- a/arch/arm64/kvm/reset.c
+++ b/arch/arm64/kvm/reset.c
@@ -161,6 +161,7 @@ void kvm_arm_vcpu_destroy(struct kvm_vcpu *vcpu)
 	if (sve_state)
 		kvm_unshare_hyp(sve_state, sve_state + vcpu_sve_state_size(vcpu));
 	kfree(sve_state);
+	free_page((unsigned long)vcpu->arch.ctxt.vncr_array);
 	kfree(vcpu->arch.ccsidr);
 }
 
-- 
2.34.1