From 1d47191de7e15900f8fbfe7cccd7c6e1c2d7c31a Mon Sep 17 00:00:00 2001 From: Christoffer Dall Date: Tue, 3 Jul 2018 22:54:14 +0200 Subject: 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 Signed-off-by: Christoffer Dall Signed-off-by: Marc Zyngier --- virt/kvm/arm/vgic/vgic-init.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'virt') diff --git a/virt/kvm/arm/vgic/vgic-init.c b/virt/kvm/arm/vgic/vgic-init.c index 2673efce65f3..b71417913741 100644 --- a/virt/kvm/arm/vgic/vgic-init.c +++ b/virt/kvm/arm/vgic/vgic-init.c @@ -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; -- cgit v1.2.3-59-g8ed1b