vfio-pci: Re-order device reset

Move the device reset to the end of our disable path, the device
should already be stopped from pci_disable_device().  This also allows
us to manipulate the save/restore to avoid the save/reset/restore +
save/restore that we had before.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/pci/vfio_pci.c

@@ -92,9 +92,10 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
 
 static void vfio_pci_disable(struct vfio_pci_device *vdev)
 {
+	struct pci_dev *pdev = vdev->pdev;
 	int bar;
 
-	pci_disable_device(vdev->pdev);
+	pci_disable_device(pdev);
 
 	vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |
 				VFIO_IRQ_SET_ACTION_TRIGGER,
@@ -104,22 +105,40 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
 
 	vfio_config_free(vdev);
 
-	pci_reset_function(vdev->pdev);
-
-	if (pci_load_and_free_saved_state(vdev->pdev,
-					  &vdev->pci_saved_state) == 0)
-		pci_restore_state(vdev->pdev);
-	else
-		pr_info("%s: Couldn't reload %s saved state\n",
-			__func__, dev_name(&vdev->pdev->dev));
-
 	for (bar = PCI_STD_RESOURCES; bar <= PCI_STD_RESOURCE_END; bar++) {
 		if (!vdev->barmap[bar])
 			continue;
-		pci_iounmap(vdev->pdev, vdev->barmap[bar]);
-		pci_release_selected_regions(vdev->pdev, 1 << bar);
+		pci_iounmap(pdev, vdev->barmap[bar]);
+		pci_release_selected_regions(pdev, 1 << bar);
 		vdev->barmap[bar] = NULL;
 	}
+
+	/*
+	 * If we have saved state, restore it.  If we can reset the device,
+	 * even better.  Resetting with current state seems better than
+	 * nothing, but saving and restoring current state without reset
+	 * is just busy work.
+	 */
+	if (pci_load_and_free_saved_state(pdev, &vdev->pci_saved_state)) {
+		pr_info("%s: Couldn't reload %s saved state\n",
+			__func__, dev_name(&pdev->dev));
+
+		if (!vdev->reset_works)
+			return;
+
+		pci_save_state(pdev);
+	}
+
+	/*
+	 * Disable INTx and MSI, presumably to avoid spurious interrupts
+	 * during reset.  Stolen from pci_reset_function()
+	 */
+	pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
+
+	if (vdev->reset_works)
+		__pci_reset_function(pdev);
+
+	pci_restore_state(pdev);
 }
 
 static void vfio_pci_release(void *device_data)