vfio: Move vfio_iommu_group_get() to vfio_register_group_dev()

We don't need to hold a reference to the group in the driver as well as
obtain a reference to the same group as the first thing
vfio_register_group_dev() does.

Since the drivers never use the group move this all into the core code.

Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20210924155705.4258-2-hch@lst.de
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

drivers/vfio/fsl-mc/vfio_fsl_mc.c

@@ -505,22 +505,13 @@ static void vfio_fsl_uninit_device(struct vfio_fsl_mc_device *vdev)
 
 static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
 {
-	struct iommu_group *group;
 	struct vfio_fsl_mc_device *vdev;
 	struct device *dev = &mc_dev->dev;
 	int ret;
 
-	group = vfio_iommu_group_get(dev);
-	if (!group) {
-		dev_err(dev, "VFIO_FSL_MC: No IOMMU group\n");
-		return -EINVAL;
-	}
-
 	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
-	if (!vdev) {
+	if (!vdev)
-		ret = -ENOMEM;
+		return -ENOMEM;
-		goto out_group_put;
-	}
 
 	vfio_init_group_dev(&vdev->vdev, dev, &vfio_fsl_mc_ops);
 	vdev->mc_dev = mc_dev;
@@ -556,8 +547,6 @@ out_device:
 out_uninit:
 	vfio_uninit_group_dev(&vdev->vdev);
 	kfree(vdev);
-out_group_put:
-	vfio_iommu_group_put(group, dev);
 	return ret;
 }
 
@@ -574,8 +563,6 @@ static int vfio_fsl_mc_remove(struct fsl_mc_device *mc_dev)
 
 	vfio_uninit_group_dev(&vdev->vdev);
 	kfree(vdev);
-	vfio_iommu_group_put(mc_dev->dev.iommu_group, dev);
-
 	return 0;
 }
 

drivers/vfio/pci/vfio_pci_core.c

@@ -1806,7 +1806,6 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_uninit_device);
 int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 {
 	struct pci_dev *pdev = vdev->pdev;
-	struct iommu_group *group;
 	int ret;
 
 	if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
@@ -1825,10 +1824,6 @@ int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 		return -EBUSY;
 	}
 
-	group = vfio_iommu_group_get(&pdev->dev);
-	if (!group)
-		return -EINVAL;
-
 	if (pci_is_root_bus(pdev->bus)) {
 		ret = vfio_assign_device_set(&vdev->vdev, vdev);
 	} else if (!pci_probe_reset_slot(pdev->slot)) {
@@ -1842,10 +1837,10 @@ int vfio_pci_core_register_device(struct vfio_pci_core_device *vdev)
 	}
 
 	if (ret)
-		goto out_group_put;
+		return ret;
 	ret = vfio_pci_vf_init(vdev);
 	if (ret)
-		goto out_group_put;
+		return ret;
 	ret = vfio_pci_vga_init(vdev);
 	if (ret)
 		goto out_vf;
@@ -1876,8 +1871,6 @@ out_power:
 		vfio_pci_set_power_state(vdev, PCI_D0);
 out_vf:
 	vfio_pci_vf_uninit(vdev);
-out_group_put:
-	vfio_iommu_group_put(group, &pdev->dev);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vfio_pci_core_register_device);
@@ -1893,8 +1886,6 @@ void vfio_pci_core_unregister_device(struct vfio_pci_core_device *vdev)
 	vfio_pci_vf_uninit(vdev);
 	vfio_pci_vga_uninit(vdev);
 
-	vfio_iommu_group_put(pdev->dev.iommu_group, &pdev->dev);
-
 	if (!disable_idle_d3)
 		vfio_pci_set_power_state(vdev, PCI_D0);
 }

drivers/vfio/platform/vfio_platform_common.c

@@ -642,7 +642,6 @@ static int vfio_platform_of_probe(struct vfio_platform_device *vdev,
 int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 			       struct device *dev)
 {
-	struct iommu_group *group;
 	int ret;
 
 	vfio_init_group_dev(&vdev->vdev, dev, &vfio_platform_ops);
@@ -663,24 +662,15 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
 		goto out_uninit;
 	}
 
-	group = vfio_iommu_group_get(dev);
-	if (!group) {
-		dev_err(dev, "No IOMMU group for device %s\n", vdev->name);
-		ret = -EINVAL;
-		goto put_reset;
-	}
-
 	ret = vfio_register_group_dev(&vdev->vdev);
 	if (ret)
-		goto put_iommu;
+		goto put_reset;
 
 	mutex_init(&vdev->igate);
 
 	pm_runtime_enable(dev);
 	return 0;
 
-put_iommu:
-	vfio_iommu_group_put(group, dev);
 put_reset:
 	vfio_platform_put_reset(vdev);
 out_uninit:
@@ -696,7 +686,6 @@ void vfio_platform_remove_common(struct vfio_platform_device *vdev)
 	pm_runtime_disable(vdev->device);
 	vfio_platform_put_reset(vdev);
 	vfio_uninit_group_dev(&vdev->vdev);
-	vfio_iommu_group_put(vdev->vdev.dev->iommu_group, vdev->vdev.dev);
 }
 EXPORT_SYMBOL_GPL(vfio_platform_remove_common);
 

drivers/vfio/vfio.c

@@ -169,15 +169,7 @@ static void vfio_release_device_set(struct vfio_device *device)
 	xa_unlock(&vfio_device_set_xa);
 }
 
-/*
+static struct iommu_group *vfio_iommu_group_get(struct device *dev)
- * vfio_iommu_group_{get,put} are only intended for VFIO bus driver probe
- * and remove functions, any use cases other than acquiring the first
- * reference for the purpose of calling vfio_register_group_dev() or removing
- * that symmetric reference after vfio_unregister_group_dev() should use the raw
- * iommu_group_{get,put} functions.  In particular, vfio_iommu_group_put()
- * removes the device from the dummy group and cannot be nested.
- */
-struct iommu_group *vfio_iommu_group_get(struct device *dev)
 {
 	struct iommu_group *group;
 	int __maybe_unused ret;
@@ -220,18 +212,6 @@ struct iommu_group *vfio_iommu_group_get(struct device *dev)
 
 	return group;
 }
-EXPORT_SYMBOL_GPL(vfio_iommu_group_get);
-
-void vfio_iommu_group_put(struct iommu_group *group, struct device *dev)
-{
-#ifdef CONFIG_VFIO_NOIOMMU
-	if (iommu_group_get_iommudata(group) == &noiommu)
-		iommu_group_remove_device(dev);
-#endif
-
-	iommu_group_put(group);
-}
-EXPORT_SYMBOL_GPL(vfio_iommu_group_put);
 
 #ifdef CONFIG_VFIO_NOIOMMU
 static void *vfio_noiommu_open(unsigned long arg)
@@ -841,7 +821,7 @@ int vfio_register_group_dev(struct vfio_device *device)
 	if (!device->dev_set)
 		vfio_assign_device_set(device, device);
 
-	iommu_group = iommu_group_get(device->dev);
+	iommu_group = vfio_iommu_group_get(device->dev);
 	if (!iommu_group)
 		return -EINVAL;
 
@@ -849,6 +829,10 @@ int vfio_register_group_dev(struct vfio_device *device)
 	if (!group) {
 		group = vfio_create_group(iommu_group);
 		if (IS_ERR(group)) {
+#ifdef CONFIG_VFIO_NOIOMMU
+			if (iommu_group_get_iommudata(iommu_group) == &noiommu)
+				iommu_group_remove_device(device->dev);
+#endif
 			iommu_group_put(iommu_group);
 			return PTR_ERR(group);
 		}
@@ -865,6 +849,10 @@ int vfio_register_group_dev(struct vfio_device *device)
 		dev_WARN(device->dev, "Device already exists on group %d\n",
 			 iommu_group_id(iommu_group));
 		vfio_device_put(existing_device);
+#ifdef CONFIG_VFIO_NOIOMMU
+		if (iommu_group_get_iommudata(iommu_group) == &noiommu)
+			iommu_group_remove_device(device->dev);
+#endif
 		vfio_group_put(group);
 		return -EBUSY;
 	}
@@ -1010,6 +998,10 @@ void vfio_unregister_group_dev(struct vfio_device *device)
 	if (list_empty(&group->device_list))
 		wait_event(group->container_q, !group->container);
 
+#ifdef CONFIG_VFIO_NOIOMMU
+	if (iommu_group_get_iommudata(group->iommu_group) == &noiommu)
+		iommu_group_remove_device(device->dev);
+#endif
 	/* Matches the get in vfio_register_group_dev() */
 	vfio_group_put(group);
 }

include/linux/vfio.h

@@ -71,9 +71,6 @@ struct vfio_device_ops {
 	int	(*match)(struct vfio_device *vdev, char *buf);
 };
 
-extern struct iommu_group *vfio_iommu_group_get(struct device *dev);
-extern void vfio_iommu_group_put(struct iommu_group *group, struct device *dev);
-
 void vfio_init_group_dev(struct vfio_device *device, struct device *dev,
 			 const struct vfio_device_ops *ops);
 void vfio_uninit_group_dev(struct vfio_device *device);