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.
Solve this by waiting for all vcpus to be halted after emmiting the halt request.
Signed-off-by: Julien Thierry julien.thierry@arm.com Suggested-by: Marc Zyngier marc.zyngier@arm.com Cc: Christoffer Dall christoffer.dall@arm.com Cc: Marc Zyngier marc.zyngier@arm.com Cc: stable@vger.kernel.org --- virt/kvm/arm/vgic/vgic-mmio.c | 36 ++++++++++++++---------------------- 1 file changed, 14 insertions(+), 22 deletions(-)
diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c index f56ff1c..5c76a92 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 +347,21 @@ 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) { + if (tmp == vcpu) + continue; + + while (tmp->cpu != -1) + cond_resched(); + } + } }
/* See vgic_change_active_prepare */