From: Julien Thierry <[email protected]> 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 <[email protected]> Suggested-by: Christoffer Dall <[email protected]> Cc: [email protected] Signed-off-by: Marc Zyngier <[email protected]> --- 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 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
