Commit 1d47191d authored Jul 03, 2018 by Christoffer Dall Committed by Marc Zyngier Jul 21, 2018

KVM: arm/arm64: Fix vgic init race



The vgic_init function can race with kvm_arch_vcpu_create() which does
not hold kvm_lock() and we therefore have no synchronization primitives
to ensure we're doing the right thing.

As the user is trying to initialize or run the VM while at the same time
creating more VCPUs, we just have to refuse to initialize the VGIC in
this case rather than silently failing with a broken VCPU.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

parent de737089

virt/kvm/arm/vgic/vgic-init.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -271,6 +271,10 @@ int vgic_init(struct kvm *kvm)
		if (vgic_initialized(kvm))
		return 0;

		/* Are we also in the middle of creating a VCPU? */
		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;