iommufd: Add IOMMU_GET_HW_INFO

Under nested IOMMU translation, userspace owns the stage-1 translation
table (e.g. the stage-1 page table of Intel VT-d or the context table of
ARM SMMUv3, and etc.). Stage-1 translation tables are vendor specific, and
need to be compatible with the underlying IOMMU hardware. Hence, userspace
should know the IOMMU hardware capability before creating and configuring
the stage-1 translation table to kernel.

This adds IOMMU_GET_HW_INFO ioctl to query the IOMMU hardware information
(a.k.a capability) for a given device. The returned data is vendor
specific, userspace needs to decode it with the structure by the output
@out_data_type field.

As only physical devices have IOMMU hardware, so this will return error if
the given device is not a physical device.

Link: https://lore.kernel.org/r/20230818101033.4100-4-yi.l.liu@intel.com
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Co-developed-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 5a45b8ba2e26..2c58670011fe 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -296,6 +296,7 @@ iommufd_get_device(struct iommufd_ucmd *ucmd, u32 id)
 }
 
 void iommufd_device_destroy(struct iommufd_object *obj);
+int iommufd_get_hw_info(struct iommufd_ucmd *ucmd);
 
 struct iommufd_access {
 	struct iommufd_object obj;