KVM: arm64: gic-v5: Create and initialise vgic_v5

Update kvm_vgic_create to create a vgic_v5 device. When creating a
vgic, FEAT_GCIE in the ID_AA64PFR2 is only exposed to vgic_v5-based
guests, and is hidden otherwise. GIC in ~ID_AA64PFR0_EL1 is never
exposed for a vgic_v5 guest.

When initialising a vgic_v5, skip kvm_vgic_dist_init as GICv5 doesn't
support one. The current vgic_v5 implementation only supports PPIs, so
no SPIs are initialised either.

The current vgic_v5 support doesn't extend to nested guests. Therefore,
the init of vgic_v5 for a nested guest is failed in vgic_v5_init.

As the current vgic_v5 doesn't require any resources to be mapped,
vgic_v5_map_resources is simply used to check that the vgic has indeed
been initialised. Again, this will change as more GICv5 support is
merged in.

Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Link: https://patch.msgid.link/20260319154937.3619520-29-sascha.bischoff@arm.com
Signed-off-by: Marc Zyngier <maz@kernel.org>

arch/arm64/kvm/vgic/vgic-init.c

@@ -66,7 +66,7 @@ static int vgic_allocate_private_irqs_locked(struct kvm_vcpu *vcpu, u32 type);
  * or through the generic KVM_CREATE_DEVICE API ioctl.
  * irqchip_in_kernel() tells you if this function succeeded or not.
  * @kvm: kvm struct pointer
- * @type: KVM_DEV_TYPE_ARM_VGIC_V[23]
+ * @type: KVM_DEV_TYPE_ARM_VGIC_V[235]
  */
 int kvm_vgic_create(struct kvm *kvm, u32 type)
 {
@@ -131,8 +131,11 @@ int kvm_vgic_create(struct kvm *kvm, u32 type)
 
 	if (type == KVM_DEV_TYPE_ARM_VGIC_V2)
 		kvm->max_vcpus = VGIC_V2_MAX_CPUS;
-	else
+	else if (type == KVM_DEV_TYPE_ARM_VGIC_V3)
 		kvm->max_vcpus = VGIC_V3_MAX_CPUS;
+	else if (type == KVM_DEV_TYPE_ARM_VGIC_V5)
+		kvm->max_vcpus = min(VGIC_V5_MAX_CPUS,
+				     kvm_vgic_global_state.max_gic_vcpus);
 
 	if (atomic_read(&kvm->online_vcpus) > kvm->max_vcpus) {
 		ret = -E2BIG;
@@ -426,22 +429,28 @@ int vgic_init(struct kvm *kvm)
 	if (kvm->created_vcpus != atomic_read(&kvm->online_vcpus))
 		return -EBUSY;
 
-	/* freeze the number of spis */
-	if (!dist->nr_spis)
-		dist->nr_spis = VGIC_NR_IRQS_LEGACY - VGIC_NR_PRIVATE_IRQS;
+	if (!vgic_is_v5(kvm)) {
+		/* freeze the number of spis */
+		if (!dist->nr_spis)
+			dist->nr_spis = VGIC_NR_IRQS_LEGACY - VGIC_NR_PRIVATE_IRQS;
 
-	ret = kvm_vgic_dist_init(kvm, dist->nr_spis);
-	if (ret)
-		goto out;
-
-	/*
-	 * Ensure vPEs are allocated if direct IRQ injection (e.g. vSGIs,
-	 * vLPIs) is supported.
-	 */
-	if (vgic_supports_direct_irqs(kvm)) {
-		ret = vgic_v4_init(kvm);
+		ret = kvm_vgic_dist_init(kvm, dist->nr_spis);
 		if (ret)
-			goto out;
+			return ret;
+
+		/*
+		 * Ensure vPEs are allocated if direct IRQ injection (e.g. vSGIs,
+		 * vLPIs) is supported.
+		 */
+		if (vgic_supports_direct_irqs(kvm)) {
+			ret = vgic_v4_init(kvm);
+			if (ret)
+				return ret;
+		}
+	} else {
+		ret = vgic_v5_init(kvm);
+		if (ret)
+			return ret;
 	}
 
 	kvm_for_each_vcpu(idx, vcpu, kvm)
@@ -449,12 +458,12 @@ int vgic_init(struct kvm *kvm)
 
 	ret = kvm_vgic_setup_default_irq_routing(kvm);
 	if (ret)
-		goto out;
+		return ret;
 
 	vgic_debug_init(kvm);
 	dist->initialized = true;
-out:
-	return ret;
+
+	return 0;
 }
 
 static void kvm_vgic_dist_destroy(struct kvm *kvm)
@@ -598,6 +607,7 @@ int vgic_lazy_init(struct kvm *kvm)
 int kvm_vgic_map_resources(struct kvm *kvm)
 {
 	struct vgic_dist *dist = &kvm->arch.vgic;
+	bool needs_dist = true;
 	enum vgic_type type;
 	gpa_t dist_base;
 	int ret = 0;
@@ -616,12 +626,16 @@ int kvm_vgic_map_resources(struct kvm *kvm)
 	if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2) {
 		ret = vgic_v2_map_resources(kvm);
 		type = VGIC_V2;
-	} else {
+	} else if (dist->vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3) {
 		ret = vgic_v3_map_resources(kvm);
 		type = VGIC_V3;
+	} else {
+		ret = vgic_v5_map_resources(kvm);
+		type = VGIC_V5;
+		needs_dist = false;
 	}
 
-	if (ret)
+	if (ret || !needs_dist)
 		goto out;
 
 	dist_base = dist->vgic_dist_base;

arch/arm64/kvm/vgic/vgic-v5.c

@@ -87,6 +87,32 @@ int vgic_v5_probe(const struct gic_kvm_info *info)
 	return 0;
 }
 
+int vgic_v5_init(struct kvm *kvm)
+{
+	struct kvm_vcpu *vcpu;
+	unsigned long idx;
+
+	if (vgic_initialized(kvm))
+		return 0;
+
+	kvm_for_each_vcpu(idx, vcpu, kvm) {
+		if (vcpu_has_nv(vcpu)) {
+			kvm_err("Nested GICv5 VMs are currently unsupported\n");
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+int vgic_v5_map_resources(struct kvm *kvm)
+{
+	if (!vgic_initialized(kvm))
+		return -EBUSY;
+
+	return 0;
+}
+
 int vgic_v5_finalize_ppi_state(struct kvm *kvm)
 {
 	struct kvm_vcpu *vcpu0;

arch/arm64/kvm/vgic/vgic.h

@@ -364,6 +364,8 @@ void vgic_debug_init(struct kvm *kvm);
 void vgic_debug_destroy(struct kvm *kvm);
 
 int vgic_v5_probe(const struct gic_kvm_info *info);
+int vgic_v5_init(struct kvm *kvm);
+int vgic_v5_map_resources(struct kvm *kvm);
 void vgic_v5_set_ppi_ops(struct kvm_vcpu *vcpu, u32 vintid);
 bool vgic_v5_has_pending_ppi(struct kvm_vcpu *vcpu);
 void vgic_v5_flush_ppi_state(struct kvm_vcpu *vcpu);

include/kvm/arm_vgic.h

@@ -21,6 +21,7 @@
 #include <linux/irqchip/arm-gic-v4.h>
 #include <linux/irqchip/arm-gic-v5.h>
 
+#define VGIC_V5_MAX_CPUS	512
 #define VGIC_V3_MAX_CPUS	512
 #define VGIC_V2_MAX_CPUS	8
 #define VGIC_NR_IRQS_LEGACY     256