[PATCH v2 2/4] KVM: arm64: vgic: Don't leak the SPI array when init is retried

[Fuad Tabba <fuad.tabba@linux.dev>]

Nothing latches a failed vgic_init(), so userspace can retry
KVM_DEV_ARM_VGIC_CTRL_INIT after a failure past kvm_vgic_dist_init().
kvm_vgic_setup_default_irq_routing() is the reachable case, running on
every configuration. Each retry overwrites dist->spis and only the last
allocation is freed at teardown, leaking up to 960 struct vgic_irq,
about 90KB, per attempt.

Return early when the array is already allocated, as
vgic_allocate_private_irqs_locked() and vgic_v4_init() do.

Fixes: ad275b8bb1e65 ("KVM: arm/arm64: vgic-new: vgic_init: implement vgic_init")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/vgic/vgic-init.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/vgic/vgic-init.c b/arch/arm64/kvm/vgic/vgic-init.c
index 907057881b26a..d4cf143f3ae6b 100644
--- a/arch/arm64/kvm/vgic/vgic-init.c
+++ b/arch/arm64/kvm/vgic/vgic-init.c
@@ -210,6 +210,9 @@ static int kvm_vgic_dist_init(struct kvm *kvm, unsigned int nr_spis)
 	struct kvm_vcpu *vcpu0 = kvm_get_vcpu(kvm, 0);
 	int i;
 
+	if (dist->spis)
+		return 0;
+
 	dist->active_spis = (atomic_t)ATOMIC_INIT(0);
 	dist->spis = kzalloc_objs(struct vgic_irq, nr_spis, GFP_KERNEL_ACCOUNT);
 	if (!dist->spis)
-- 
2.39.5