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authorChristoffer Dall <christoffer.dall@arm.com>2018-07-03 22:54:14 +0200
committerMarc Zyngier <marc.zyngier@arm.com>2018-07-21 16:02:07 +0100
commit1d47191de7e15900f8fbfe7cccd7c6e1c2d7c31a (patch)
tree2595c1920c0bda904e609e1d504afca86f7d2963
parentde73708915adc1b3f05e617a86da6b2d68fae141 (diff)
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>
-rw-r--r--virt/kvm/arm/vgic/vgic-init.c4
1 files changed, 4 insertions, 0 deletions
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;