Revert "virtio_pci: harden MSI-X interrupts"

This reverts commit 9e35276. Issue
were reported for the drivers that are using affinity managed IRQ
where manually toggling IRQ status is not expected. And we forget to
enable the interrupts in the restore path as well.

In the future, we will rework on the interrupt hardening.

Fixes: 9e35276 ("virtio_pci: harden MSI-X interrupts")
Reported-by: Marc Zyngier <maz@kernel.org>
Reported-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: https://lore.kernel.org/r/20220323031524.6555-2-jasowang@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

Author: jasowang

drivers/virtio/virtio_pci_common.c

@@ -24,8 +24,8 @@ MODULE_PARM_DESC(force_legacy,
 		 "Force legacy mode for transitional virtio 1 devices");
 #endif
 
-/* disable irq handlers */
-void vp_disable_cbs(struct virtio_device *vdev)
+/* wait for pending irq handlers */
+void vp_synchronize_vectors(struct virtio_device *vdev)
 {
 	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
 	int i;
@@ -34,20 +34,7 @@ void vp_disable_cbs(struct virtio_device *vdev)
 		synchronize_irq(vp_dev->pci_dev->irq);
 
 	for (i = 0; i < vp_dev->msix_vectors; ++i)
-		disable_irq(pci_irq_vector(vp_dev->pci_dev, i));
-}
-
-/* enable irq handlers */
-void vp_enable_cbs(struct virtio_device *vdev)
-{
-	struct virtio_pci_device *vp_dev = to_vp_device(vdev);
-	int i;
-
-	if (vp_dev->intx_enabled)
-		return;
-
-	for (i = 0; i < vp_dev->msix_vectors; ++i)
-		enable_irq(pci_irq_vector(vp_dev->pci_dev, i));
+		synchronize_irq(pci_irq_vector(vp_dev->pci_dev, i));
 }
 
 /* the notify function used when creating a virt queue */
@@ -154,8 +141,7 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
 	snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
 		 "%s-config", name);
 	err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
-			  vp_config_changed, IRQF_NO_AUTOEN,
-			  vp_dev->msix_names[v],
+			  vp_config_changed, 0, vp_dev->msix_names[v],
 			  vp_dev);
 	if (err)
 		goto error;
@@ -174,8 +160,7 @@ static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
 		snprintf(vp_dev->msix_names[v], sizeof *vp_dev->msix_names,
 			 "%s-virtqueues", name);
 		err = request_irq(pci_irq_vector(vp_dev->pci_dev, v),
-				  vp_vring_interrupt, IRQF_NO_AUTOEN,
-				  vp_dev->msix_names[v],
+				  vp_vring_interrupt, 0, vp_dev->msix_names[v],
 				  vp_dev);
 		if (err)
 			goto error;
@@ -352,7 +337,7 @@ static int vp_find_vqs_msix(struct virtio_device *vdev, unsigned nvqs,
 			 "%s-%s",
 			 dev_name(&vp_dev->vdev.dev), names[i]);
 		err = request_irq(pci_irq_vector(vp_dev->pci_dev, msix_vec),
-				  vring_interrupt, IRQF_NO_AUTOEN,
+				  vring_interrupt, 0,
 				  vp_dev->msix_names[msix_vec],
 				  vqs[i]);
 		if (err)

drivers/virtio/virtio_pci_common.h

@@ -101,10 +101,8 @@ static struct virtio_pci_device *to_vp_device(struct virtio_device *vdev)
 	return container_of(vdev, struct virtio_pci_device, vdev);
 }
 
-/* disable irq handlers */
-void vp_disable_cbs(struct virtio_device *vdev);
-/* enable irq handlers */
-void vp_enable_cbs(struct virtio_device *vdev);
+/* wait for pending irq handlers */
+void vp_synchronize_vectors(struct virtio_device *vdev);
 /* the notify function used when creating a virt queue */
 bool vp_notify(struct virtqueue *vq);
 /* the config->del_vqs() implementation */

drivers/virtio/virtio_pci_legacy.c

@@ -98,8 +98,8 @@ static void vp_reset(struct virtio_device *vdev)
 	/* Flush out the status write, and flush in device writes,
 	 * including MSi-X interrupts, if any. */
 	vp_legacy_get_status(&vp_dev->ldev);
-	/* Disable VQ/configuration callbacks. */
-	vp_disable_cbs(vdev);
+	/* Flush pending VQ/configuration callbacks. */
+	vp_synchronize_vectors(vdev);
 }
 
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
@@ -185,7 +185,6 @@ static void del_vq(struct virtio_pci_vq_info *info)
 }
 
 static const struct virtio_config_ops virtio_pci_config_ops = {
-	.enable_cbs	= vp_enable_cbs,
 	.get		= vp_get,
 	.set		= vp_set,
 	.get_status	= vp_get_status,

drivers/virtio/virtio_pci_modern.c

@@ -172,8 +172,8 @@ static void vp_reset(struct virtio_device *vdev)
 	 */
 	while (vp_modern_get_status(mdev))
 		msleep(1);
-	/* Disable VQ/configuration callbacks. */
-	vp_disable_cbs(vdev);
+	/* Flush pending VQ/configuration callbacks. */
+	vp_synchronize_vectors(vdev);
 }
 
 static u16 vp_config_vector(struct virtio_pci_device *vp_dev, u16 vector)
@@ -380,7 +380,6 @@ static bool vp_get_shm_region(struct virtio_device *vdev,
 }
 
 static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
-	.enable_cbs	= vp_enable_cbs,
 	.get		= NULL,
 	.set		= NULL,
 	.generation	= vp_generation,
@@ -398,7 +397,6 @@ static const struct virtio_config_ops virtio_pci_config_nodev_ops = {
 };
 
 static const struct virtio_config_ops virtio_pci_config_ops = {
-	.enable_cbs	= vp_enable_cbs,
 	.get		= vp_get,
 	.set		= vp_set,
 	.generation	= vp_generation,