[PATCH 1/2] KVM: arm64: vgic-v4: Don't allocate vPEs for a GICv2 VM

[Fuad Tabba]

KVM can run a GICv2 VM on a GICv4.0 host whose CPU interface supports
legacy operation. Such a VM has no LPIs and never uses vPEs, so
vgic_supports_direct_irqs() is false for it and kvm_vgic_dist_destroy()
never tears them down. However, userspace can still create an ITS for
it. Once the vgic is initialised, vgic_its_create() calls
vgic_v4_init(), which allocates the vPEs and requests a doorbell IRQ for
each vCPU. They're then never freed, and each doorbell handler stays
registered with a vCPU that's freed with the VM.

Only allocate vPEs for a GICv3 VM.

Fixes: 74fe55dc9ab77 ("KVM: arm/arm64: GICv4: Add init/teardown of the per-VM vPE irq domain")
Cc: stable at vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba at linux.dev>
---
 arch/arm64/kvm/vgic/vgic-v4.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v4.c b/arch/arm64/kvm/vgic/vgic-v4.c
index ed236f083f0d7..a01de4de608a6 100644
--- a/arch/arm64/kvm/vgic/vgic-v4.c
+++ b/arch/arm64/kvm/vgic/vgic-v4.c
@@ -248,7 +248,7 @@ int vgic_v4_init(struct kvm *kvm)
 
 	lockdep_assert_held(&kvm->arch.config_lock);
 
-	if (!kvm_vgic_global_state.has_gicv4)
+	if (!kvm_vgic_global_state.has_gicv4 || dist->vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3)
 		return 0; /* Nothing to see here... move along. */
 
 	if (dist->its_vm.vpes)
-- 
2.47.3