virtio: Add reset() callback

When the guest writes a status of 0, the device should be reset. Add a
reset() callback for the transport layer to reset all queues and their
ioeventfd.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

6 files changed, 37 insertions, 11 deletions

diff --git a/include/kvm/virtio-mmio.h b/include/kvm/virtio-mmio.h
index 835f421b..0528947a 100644
--- a/include/kvm/virtio-mmio.h
+++ b/include/kvm/virtio-mmio.h
@@ -54,6 +54,7 @@ struct virtio_mmio {
 int virtio_mmio_signal_vq(struct kvm *kvm, struct virtio_device *vdev, u32 vq);
 int virtio_mmio_signal_config(struct kvm *kvm, struct virtio_device *vdev);
 int virtio_mmio_exit(struct kvm *kvm, struct virtio_device *vdev);
+int virtio_mmio_reset(struct kvm *kvm, struct virtio_device *vdev);
 int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		      int device_id, int subsys_id, int class);
 void virtio_mmio_assign_irq(struct device_header *dev_hdr);
diff --git a/include/kvm/virtio-pci.h b/include/kvm/virtio-pci.h
index b70cadd8..278a2595 100644
--- a/include/kvm/virtio-pci.h
+++ b/include/kvm/virtio-pci.h
@@ -55,6 +55,7 @@ struct virtio_pci {
 int virtio_pci__signal_vq(struct kvm *kvm, struct virtio_device *vdev, u32 vq);
 int virtio_pci__signal_config(struct kvm *kvm, struct virtio_device *vdev);
 int virtio_pci__exit(struct kvm *kvm, struct virtio_device *vdev);
+int virtio_pci__reset(struct kvm *kvm, struct virtio_device *vdev);
 int virtio_pci__init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		     int device_id, int subsys_id, int class);
 
diff --git a/include/kvm/virtio.h b/include/kvm/virtio.h
index f35c74df..19b91373 100644
--- a/include/kvm/virtio.h
+++ b/include/kvm/virtio.h
@@ -201,6 +201,7 @@ struct virtio_ops {
 	int (*init)(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		    int device_id, int subsys_id, int class);
 	int (*exit)(struct kvm *kvm, struct virtio_device *vdev);
+	int (*reset)(struct kvm *kvm, struct virtio_device *vdev);
 };
 
 int virtio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
diff --git a/virtio/core.c b/virtio/core.c
index 67d41142..e10ec362 100644
--- a/virtio/core.c
+++ b/virtio/core.c
@@ -241,6 +241,13 @@ void virtio_notify_status(struct kvm *kvm, struct virtio_device *vdev,
 	} else if (!status && (vdev->status & VIRTIO__STATUS_START)) {
 		vdev->status &= ~VIRTIO__STATUS_START;
 		ext_status |= VIRTIO__STATUS_STOP;
+
+		/*
+		 * Reset virtqueues and stop all traffic now, so that the device
+		 * can safely reset the backend in notify_status().
+		 */
+		if (ext_status & VIRTIO__STATUS_STOP)
+			vdev->ops->reset(kvm, vdev);
 	}
 
 	if (vdev->ops->notify_status)
@@ -264,6 +271,7 @@ int virtio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		vdev->ops->signal_config	= virtio_pci__signal_config;
 		vdev->ops->init			= virtio_pci__init;
 		vdev->ops->exit			= virtio_pci__exit;
+		vdev->ops->reset		= virtio_pci__reset;
 		vdev->ops->init(kvm, dev, vdev, device_id, subsys_id, class);
 		break;
 	case VIRTIO_MMIO:
@@ -276,6 +284,7 @@ int virtio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 		vdev->ops->signal_config	= virtio_mmio_signal_config;
 		vdev->ops->init			= virtio_mmio_init;
 		vdev->ops->exit			= virtio_mmio_exit;
+		vdev->ops->reset		= virtio_mmio_reset;
 		vdev->ops->init(kvm, dev, vdev, device_id, subsys_id, class);
 		break;
 	default:
diff --git a/virtio/mmio.c b/virtio/mmio.c
index 4b8c20ec..eff147aa 100644
--- a/virtio/mmio.c
+++ b/virtio/mmio.c
@@ -326,15 +326,23 @@ int virtio_mmio_init(struct kvm *kvm, void *dev, struct virtio_device *vdev,
 	return 0;
 }
 
+int virtio_mmio_reset(struct kvm *kvm, struct virtio_device *vdev)
+{
+	int vq;
+	struct virtio_mmio *vmmio = vdev->virtio;
+
+	for (vq = 0; vq < vdev->ops->get_vq_count(kvm, vmmio->dev); vq++)
+		virtio_mmio_exit_vq(kvm, vdev, vq);
+
+	return 0;
+}
+
 int virtio_mmio_exit(struct kvm *kvm, struct virtio_device *vdev)
 {
 	struct virtio_mmio *vmmio = vdev->virtio;
-	int i;
 
+	virtio_mmio_reset(kvm, vdev);
 	kvm__deregister_mmio(kvm, vmmio->addr);
 
-	for (i = 0; i < VIRTIO_MMIO_MAX_VQ; i++)
-		ioeventfd__del_event(vmmio->addr + VIRTIO_MMIO_QUEUE_NOTIFY, i);
-
 	return 0;
 }
diff --git a/virtio/pci.c b/virtio/pci.c
index 2da2d3f8..99653cad 100644
--- a/virtio/pci.c
+++ b/virtio/pci.c
@@ -77,8 +77,8 @@ static void virtio_pci_exit_vq(struct kvm *kvm, struct virtio_device *vdev,
 {
 	struct virtio_pci *vpci = vdev->virtio;
 
-	ioeventfd__del_event(vpci->port_addr + VIRTIO_PCI_QUEUE_NOTIFY, vq);
 	ioeventfd__del_event(vpci->mmio_addr + VIRTIO_PCI_QUEUE_NOTIFY, vq);
+	ioeventfd__del_event(vpci->port_addr + VIRTIO_PCI_QUEUE_NOTIFY, vq);
 	virtio_exit_vq(kvm, vdev, vpci->dev, vq);
 }
 
@@ -522,19 +522,25 @@ free_ioport:
 	return r;
 }
 
+int virtio_pci__reset(struct kvm *kvm, struct virtio_device *vdev)
+{
+	int vq;
+	struct virtio_pci *vpci = vdev->virtio;
+
+	for (vq = 0; vq < vdev->ops->get_vq_count(kvm, vpci->dev); vq++)
+		virtio_pci_exit_vq(kvm, vdev, vq);
+
+	return 0;
+}
+
 int virtio_pci__exit(struct kvm *kvm, struct virtio_device *vdev)
 {
 	struct virtio_pci *vpci = vdev->virtio;
-	int i;
 
+	virtio_pci__reset(kvm, vdev);
 	kvm__deregister_mmio(kvm, vpci->mmio_addr);
 	kvm__deregister_mmio(kvm, vpci->msix_io_block);
 	ioport__unregister(kvm, vpci->port_addr);
 
-	for (i = 0; i < VIRTIO_PCI_MAX_VQ; i++) {
-		ioeventfd__del_event(vpci->port_addr + VIRTIO_PCI_QUEUE_NOTIFY, i);
-		ioeventfd__del_event(vpci->mmio_addr + VIRTIO_PCI_QUEUE_NOTIFY, i);
-	}
-
 	return 0;
 }