From: Julien Thierry <julien.thierry@xxxxxxx>
To change the active state of an MMIO, halt is requested for all vcpus of
the affected guest before modifying the IRQ state. This is done by calling
cond_resched_lock() in vgic_mmio_change_active(). However interrupts are
disabled at this point and we cannot reschedule a vcpu.
We actually don't need any of this, as kvm_arm_halt_guest ensures that
all the other vcpus are out of the guest. Let's just drop that useless
code.
Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx>
Suggested-by: Christoffer Dall <christoffer.dall@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
---
virt/kvm/arm/vgic/vgic-mmio.c | 21 ---------------------
1 file changed, 21 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
index 2b450d49a046..7c2231950c33 100644
--- a/virt/kvm/arm/vgic/vgic-mmio.c
+++ b/virt/kvm/arm/vgic/vgic-mmio.c
@@ -313,27 +313,6 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
spin_lock_irqsave(&irq->irq_lock, flags);
- /*
- * If this virtual IRQ was written into a list register, we
- * have to make sure the CPU that runs the VCPU thread has
- * synced back the LR state to the struct vgic_irq.
- *
- * As long as the conditions below are true, we know the VCPU thread
- * may be on its way back from the guest (we kicked the VCPU thread in
- * vgic_change_active_prepare) and still has to sync back this IRQ,
- * so we release and re-acquire the spin_lock to let the other thread
- * sync back the IRQ.
- *
- * When accessing VGIC state from user space, requester_vcpu is
- * NULL, which is fine, because we guarantee that no VCPUs are running
- * when accessing VGIC state from user space so irq->vcpu->cpu is
- * always -1.
- */
- while (irq->vcpu && /* IRQ may have state in an LR somewhere */
- irq->vcpu != requester_vcpu && /* Current thread is not the VCPU thread */
- irq->vcpu->cpu != -1) /* VCPU thread is running */
- cond_resched_lock(&irq->irq_lock);
-
if (irq->hw) {
vgic_hw_irq_change_active(vcpu, irq, active, !requester_vcpu);
} else {
--
2.19.2
