3 files changed, 18 insertions, 0 deletions

diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
index e1cd3cb95903..e8b82b289844 100644
--- a/virt/kvm/arm/vgic-v2.c
+++ b/virt/kvm/arm/vgic-v2.c
@@ -237,6 +237,7 @@ int vgic_v2_probe(struct device_node *vgic_node,
                  vctrl_res.start, vgic->maint_irq);
 
         vgic->type = VGIC_V2;
+        vgic->max_gic_vcpus = VGIC_V2_MAX_CPUS;
         *ops = &vgic_v2_ops;
         *params = vgic;
         goto out;
diff --git a/virt/kvm/arm/vgic-v3.c b/virt/kvm/arm/vgic-v3.c
index d14c75f4a33b..ea39bad4b004 100644
--- a/virt/kvm/arm/vgic-v3.c
+++ b/virt/kvm/arm/vgic-v3.c
@@ -235,6 +235,7 @@ int vgic_v3_probe(struct device_node *vgic_node,
         vgic->vcpu_base = vcpu_res.start;
         vgic->vctrl_base = NULL;
         vgic->type = VGIC_V3;
+        vgic->max_gic_vcpus = KVM_MAX_VCPUS;
 
         kvm_info("%s@%llx IRQ%d\n", vgic_node->name,
                  vcpu_res.start, vgic->maint_irq);
diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 1c3b75eb28f0..2126bf5b0035 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -1878,6 +1878,17 @@ static int vgic_vcpu_init_maps(struct kvm_vcpu *vcpu, int nr_irqs)
         return 0;
 }
 
+/**
+ * kvm_vgic_get_max_vcpus - Get the maximum number of VCPUs allowed by HW
+ *
+ * The host's GIC naturally limits the maximum amount of VCPUs a guest
+ * can use.
+ */
+int kvm_vgic_get_max_vcpus(void)
+{
+        return vgic->max_gic_vcpus;
+}
+
 void kvm_vgic_destroy(struct kvm *kvm)
 {
         struct vgic_dist *dist = &kvm->arch.vgic;
@@ -2072,6 +2083,8 @@ static void vgic_v2_init_emulation(struct kvm *kvm)
         dist->vm_ops.add_sgi_source = vgic_v2_add_sgi_source;
         dist->vm_ops.init_model = vgic_v2_init_model;
         dist->vm_ops.map_resources = vgic_v2_map_resources;
+
+        kvm->arch.max_vcpus = VGIC_V2_MAX_CPUS;
 }
 
 static int init_vgic_model(struct kvm *kvm, int type)
@@ -2084,6 +2097,9 @@ static int init_vgic_model(struct kvm *kvm, int type)
                 return -ENODEV;
         }
 
+        if (atomic_read(&kvm->online_vcpus) > kvm->arch.max_vcpus)
+                return -E2BIG;
+
         return 0;
 }