[PATCH 13/17] iommufd/device: Report supported stage-1 page table types

[Yi Liu]

This provides a way for userspace to probe supported stage-1 page table
types on hardware IOMMU. This is helpful when the user-managed page table
is used by hardware IOMMU. e.g. nested translation.

This commit reports the supported types for IOMMU_DEVICE_DATA_INTEL_VTD.

Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/iommu/iommufd/device.c | 7 +++++++
 drivers/iommu/iommufd/main.c   | 2 +-
 include/uapi/linux/iommufd.h   | 7 +++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index c19e2f54a44f..826441c6005d 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -224,6 +224,13 @@ int iommufd_device_get_info(struct iommufd_ucmd *ucmd)
 	cmd->out_device_type = ops->driver_type;
 	cmd->data_len = data_len;
 
+	if (ops->driver_type != IOMMU_DEVICE_DATA_SELFTEST)
+		cmd->out_pgtbl_type_bitmap = iommufd_supported_pgtbl_types[ops->driver_type];
+#ifdef CONFIG_IOMMUFD_TEST
+	else
+		cmd->out_pgtbl_type_bitmap = 0;
+#endif
+
 	rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd));
 
 out_free_data:
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 6e2d8805daf3..d8bac1303b33 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -290,7 +290,7 @@ struct iommufd_ioctl_op {
 static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 	IOCTL_OP(IOMMU_DESTROY, iommufd_destroy, struct iommu_destroy, id),
 	IOCTL_OP(IOMMU_DEVICE_GET_INFO, iommufd_device_get_info, struct iommu_device_info,
-		 __reserved),
+		 out_pgtbl_type_bitmap),
 	IOCTL_OP(IOMMU_HWPT_ALLOC, iommufd_hwpt_alloc, struct iommu_hwpt_alloc,
 		 __reserved),
 	IOCTL_OP(IOMMU_HWPT_INVALIDATE, iommufd_hwpt_invalidate,
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index cb6a9ee215f4..2c7533d843bc 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -396,6 +396,8 @@ enum iommu_pgtbl_data_type {
  * @out_device_type: Output the underlying iommu hardware type, it is
  *		   one of enum iommu_device_data_type.
  * @__reserved: Must be 0
+ * @out_pgtbl_type_bitmap: Output the supported page table type. Each
+ *			   bit is defined in enum iommu_pgtbl_data_type.
  *
  * Query the hardware iommu capability for given device which has been
  * bound to iommufd. @data_len is set to be the size of the buffer to
@@ -408,6 +410,10 @@ enum iommu_pgtbl_data_type {
  *
  * The @out_device_type will be filled if the ioctl succeeds. It would
  * be used to decode the data filled in the buffer pointed by @data_ptr.
+ *
+ * @out_pgtbl_type_bitmap tells the userspace the supported page tables.
+ * This differs per @out_device_type. Userspace should check it before
+ * allocating hw_pagetable in userspace.
  */
 struct iommu_device_info {
 	__u32 size;
@@ -417,6 +423,7 @@ struct iommu_device_info {
 	__aligned_u64 data_ptr;
 	__u32 out_device_type;
 	__u32 __reserved;
+	__aligned_u64 out_pgtbl_type_bitmap;
 };
 #define IOMMU_DEVICE_GET_INFO _IO(IOMMUFD_TYPE, IOMMUFD_CMD_DEVICE_GET_INFO)
 
-- 
2.34.1