[PATCH v12 21/24] vfio: Determine noiommu device in __vfio_register_dev()

[Yi Liu <yi.l.liu@xxxxxxxxx>]

This moves the noiommu device determination and noiommu taint out of
vfio_group_find_or_alloc(). noiommu device is determined in
__vfio_register_dev() and result is stored in flag vfio_device->noiommu,
the noiommu taint is added in the end of __vfio_register_dev().

This is also a preparation for compiling out vfio_group infrastructure
as it makes the noiommu detection and taint common between the cdev path
and group path though cdev path does not support noiommu.

Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/vfio/group.c     | 15 ---------------
 drivers/vfio/vfio_main.c | 31 ++++++++++++++++++++++++++++++-
 include/linux/vfio.h     |  1 +
 3 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 653b62f93474..64cdd0ea8825 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -668,21 +668,6 @@ static struct vfio_group *vfio_group_find_or_alloc(struct device *dev)
 	struct vfio_group *group;
 
 	iommu_group = iommu_group_get(dev);
-	if (!iommu_group && vfio_noiommu) {
-		/*
-		 * With noiommu enabled, create an IOMMU group for devices that
-		 * don't already have one, implying no IOMMU hardware/driver
-		 * exists.  Taint the kernel because we're about to give a DMA
-		 * capable device to a user without IOMMU protection.
-		 */
-		group = vfio_noiommu_group_alloc(dev, VFIO_NO_IOMMU);
-		if (!IS_ERR(group)) {
-			add_taint(TAINT_USER, LOCKDEP_STILL_OK);
-			dev_warn(dev, "Adding kernel taint for vfio-noiommu group on device\n");
-		}
-		return group;
-	}
-
 	if (!iommu_group)
 		return ERR_PTR(-EINVAL);
 
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 6d8f9b0f3637..00a699b9f76b 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -265,6 +265,18 @@ static int vfio_init_device(struct vfio_device *device, struct device *dev,
 	return ret;
 }
 
+static int vfio_device_set_noiommu(struct vfio_device *device)
+{
+	struct iommu_group *iommu_group = iommu_group_get(device->dev);
+
+	if (!iommu_group && !vfio_noiommu)
+		return -EINVAL;
+
+	device->noiommu = !iommu_group;
+	iommu_group_put(iommu_group); /* Accepts NULL */
+	return 0;
+}
+
 static int __vfio_register_dev(struct vfio_device *device,
 			       enum vfio_group_type type)
 {
@@ -277,6 +289,13 @@ static int __vfio_register_dev(struct vfio_device *device,
 		     !device->ops->detach_ioas)))
 		return -EINVAL;
 
+	/* Only physical devices can be noiommu device */
+	if (type == VFIO_IOMMU) {
+		ret = vfio_device_set_noiommu(device);
+		if (ret)
+			return ret;
+	}
+
 	/*
 	 * If the driver doesn't specify a set then the device is added to a
 	 * singleton set just for itself.
@@ -288,7 +307,8 @@ static int __vfio_register_dev(struct vfio_device *device,
 	if (ret)
 		return ret;
 
-	ret = vfio_device_set_group(device, type);
+	ret = vfio_device_set_group(device,
+				    device->noiommu ? VFIO_NO_IOMMU : type);
 	if (ret)
 		return ret;
 
@@ -301,6 +321,15 @@ static int __vfio_register_dev(struct vfio_device *device,
 
 	vfio_device_group_register(device);
 
+	if (device->noiommu) {
+		/*
+		 * noiommu deivces have no IOMMU hardware/driver.  Taint the
+		 * kernel because we're about to give a DMA capable device to
+		 * a user without IOMMU protection.
+		 */
+		add_taint(TAINT_USER, LOCKDEP_STILL_OK);
+		dev_warn(device->dev, "Adding kernel taint for vfio-noiommu on device\n");
+	}
 	return 0;
 err_out:
 	vfio_device_remove_group(device);
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e80a8ac86e46..183e620009e7 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -67,6 +67,7 @@ struct vfio_device {
 	bool iommufd_attached;
 #endif
 	bool cdev_opened:1;
+	bool noiommu:1;
 };
 
 /**
-- 
2.34.1