vfio-iommufd: Support iommufd for physical VFIO devices

This creates the iommufd_device for the physical VFIO drivers. These are
all the drivers that are calling vfio_register_group_dev() and expect the
type1 code to setup a real iommu_domain against their parent struct
device.

The design gives the driver a choice in how it gets connected to iommufd
by providing bind_iommufd/unbind_iommufd/attach_ioas callbacks to
implement as required. The core code provides three default callbacks for
physical mode using a real iommu_domain. This is suitable for drivers
using vfio_register_group_dev()

Link: https://lore.kernel.org/r/6-v4-42cd2eb0e3eb+335a-vfio_iommufd_jgg@nvidia.com
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Tested-by: Yi Liu <yi.l.liu@intel.com>
Tested-by: Lixiao Yang <lixiao.yang@intel.com>
Tested-by: Matthew Rosato <mjrosato@linux.ibm.com>
Tested-by: Yu He <yu.he@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

1 files changed, 100 insertions, 0 deletions

diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
new file mode 100644
index 000000000000..6e47a3df1a71
--- /dev/null
+++ b/drivers/vfio/iommufd.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2021-2022, NVIDIA CORPORATION & AFFILIATES
+ */
+#include <linux/vfio.h>
+#include <linux/iommufd.h>
+
+#include "vfio.h"
+
+MODULE_IMPORT_NS(IOMMUFD);
+MODULE_IMPORT_NS(IOMMUFD_VFIO);
+
+int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx)
+{
+	u32 ioas_id;
+	u32 device_id;
+	int ret;
+
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	/*
+	 * If the driver doesn't provide this op then it means the device does
+	 * not do DMA at all. So nothing to do.
+	 */
+	if (!vdev->ops->bind_iommufd)
+		return 0;
+
+	ret = vdev->ops->bind_iommufd(vdev, ictx, &device_id);
+	if (ret)
+		return ret;
+
+	ret = iommufd_vfio_compat_ioas_id(ictx, &ioas_id);
+	if (ret)
+		goto err_unbind;
+	ret = vdev->ops->attach_ioas(vdev, &ioas_id);
+	if (ret)
+		goto err_unbind;
+
+	/*
+	 * The legacy path has no way to return the device id or the selected
+	 * pt_id
+	 */
+	return 0;
+
+err_unbind:
+	if (vdev->ops->unbind_iommufd)
+		vdev->ops->unbind_iommufd(vdev);
+	return ret;
+}
+
+void vfio_iommufd_unbind(struct vfio_device *vdev)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (vdev->ops->unbind_iommufd)
+		vdev->ops->unbind_iommufd(vdev);
+}
+
+/*
+ * The physical standard ops mean that the iommufd_device is bound to the
+ * physical device vdev->dev that was provided to vfio_init_group_dev(). Drivers
+ * using this ops set should call vfio_register_group_dev()
+ */
+int vfio_iommufd_physical_bind(struct vfio_device *vdev,
+			       struct iommufd_ctx *ictx, u32 *out_device_id)
+{
+	struct iommufd_device *idev;
+
+	idev = iommufd_device_bind(ictx, vdev->dev, out_device_id);
+	if (IS_ERR(idev))
+		return PTR_ERR(idev);
+	vdev->iommufd_device = idev;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
+
+void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (vdev->iommufd_attached) {
+		iommufd_device_detach(vdev->iommufd_device);
+		vdev->iommufd_attached = false;
+	}
+	iommufd_device_unbind(vdev->iommufd_device);
+	vdev->iommufd_device = NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_unbind);
+
+int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
+{
+	int rc;
+
+	rc = iommufd_device_attach(vdev->iommufd_device, pt_id);
+	if (rc)
+		return rc;
+	vdev->iommufd_attached = true;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_physical_attach_ioas);