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 running a vcpu cannot get rescheduled.
Solve this by waiting for all vcpus to be halted after emmiting the halt
request.
Fixes commit 6c1b7521f4a07cc63bbe2dfe290efed47cdb780a ("KVM: arm/arm64:
Factor out functionality to get vgic mmio requester_vcpu")
Signed-off-by: Julien Thierry <julien.thierry@xxxxxxx>
Suggested-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: Christoffer Dall <christoffer.dall@xxxxxxx>
Cc: Marc Zyngier <marc.zyngier@xxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
virt/kvm/arm/vgic/vgic-mmio.c | 33 +++++++++++----------------------
1 file changed, 11 insertions(+), 22 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
index f56ff1c..eefd877 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 {
@@ -368,8 +347,18 @@ static void vgic_mmio_change_active(struct kvm_vcpu *vcpu, struct vgic_irq *irq,
*/
static void vgic_change_active_prepare(struct kvm_vcpu *vcpu, u32 intid)
{
- if (intid > VGIC_NR_PRIVATE_IRQS)
+ if (intid > VGIC_NR_PRIVATE_IRQS) {
+ struct kvm_vcpu *tmp;
+ int i;
+
kvm_arm_halt_guest(vcpu->kvm);
+
+ /* Wait for each vcpu to be halted */
+ kvm_for_each_vcpu(i, tmp, vcpu->kvm) {
+ while (tmp->cpu != -1)
+ cond_resched();
+ }
+ }
}
/* See vgic_change_active_prepare */
--
1.9.1
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