From defaf1587c5d7dff828f6f11c8941e5bcef00f50 Mon Sep 17 00:00:00 2001 From: Mark McLoughlin Date: Tue, 2 Dec 2008 12:16:33 +0000 Subject: KVM: fix handling of ACK from shared guest IRQ If an assigned device shares a guest irq with an emulated device then we currently interpret an ack generated by the emulated device as originating from the assigned device leading to e.g. "Unbalanced enable for IRQ 4347" from the enable_irq() in kvm_assigned_dev_ack_irq(). The fix is fairly simple - don't enable the physical device irq unless it was previously disabled. Of course, this can still lead to a situation where a non-assigned device ACK can cause the physical device irq to be reenabled before the device was serviced. However, being level sensitive, the interrupt will merely be regenerated. Signed-off-by: Mark McLoughlin Signed-off-by: Avi Kivity --- virt/kvm/kvm_main.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'virt') diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index eb70ca6c7145..fc6127cbea1f 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -170,6 +170,7 @@ static void kvm_assigned_dev_interrupt_work_handler(struct work_struct *work) KVM_ASSIGNED_DEV_GUEST_MSI) { assigned_device_msi_dispatch(assigned_dev); enable_irq(assigned_dev->host_irq); + assigned_dev->host_irq_disabled = false; } mutex_unlock(&assigned_dev->kvm->lock); kvm_put_kvm(assigned_dev->kvm); @@ -181,8 +182,12 @@ static irqreturn_t kvm_assigned_dev_intr(int irq, void *dev_id) (struct kvm_assigned_dev_kernel *) dev_id; kvm_get_kvm(assigned_dev->kvm); + schedule_work(&assigned_dev->interrupt_work); + disable_irq_nosync(irq); + assigned_dev->host_irq_disabled = true; + return IRQ_HANDLED; } @@ -196,8 +201,16 @@ static void kvm_assigned_dev_ack_irq(struct kvm_irq_ack_notifier *kian) dev = container_of(kian, struct kvm_assigned_dev_kernel, ack_notifier); + kvm_set_irq(dev->kvm, dev->irq_source_id, dev->guest_irq, 0); - enable_irq(dev->host_irq); + + /* The guest irq may be shared so this ack may be + * from another device. + */ + if (dev->host_irq_disabled) { + enable_irq(dev->host_irq); + dev->host_irq_disabled = false; + } } static void kvm_free_assigned_irq(struct kvm *kvm, -- cgit v1.2.1