From: Christoffer Dall <[email protected]> There is a small chance that the compiler could generate separate loads for the dist->propbaser which could be modified from another CPU. As we want to make sure we atomically update the entire value, and don't race with other updates, guarantee that the cmpxchg operation compares against the original value.
Acked-by: Catalin Marinas <[email protected]> Signed-off-by: Christoffer Dall <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> --- virt/kvm/arm/vgic/vgic-mmio-v3.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c index 714fa3933546..408ef06638fc 100644 --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c @@ -369,7 +369,7 @@ static void vgic_mmio_write_propbase(struct kvm_vcpu *vcpu, return; do { - old_propbaser = dist->propbaser; + old_propbaser = READ_ONCE(dist->propbaser); propbaser = old_propbaser; propbaser = update_64bit_reg(propbaser, addr & 4, len, val); propbaser = vgic_sanitise_propbaser(propbaser); @@ -397,7 +397,7 @@ static void vgic_mmio_write_pendbase(struct kvm_vcpu *vcpu, return; do { - old_pendbaser = vgic_cpu->pendbaser; + old_pendbaser = READ_ONCE(vgic_cpu->pendbaser); pendbaser = old_pendbaser; pendbaser = update_64bit_reg(pendbaser, addr & 4, len, val); pendbaser = vgic_sanitise_pendbaser(pendbaser); -- 2.11.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
