Commit 187f146d authored by Nicolin Chen's avatar Nicolin Chen Committed by Jason Gunthorpe
Browse files

iommu: Introduce get_viommu_size and viommu_init ops 

So far, a vIOMMU object has been allocated by IOMMU driver and initialized
with the driver-level structure, before it returns to the iommufd core for
core-level structure initialization. It has been requiring iommufd core to
expose some core structure/helpers in its driver.c file, which result in a
size increase of this driver module.

Meanwhile, IOMMU drivers are now requiring more vIOMMU-base structures for
some advanced feature, such as the existing vDEVICE and a future HW_QUEUE.
Initializing a core-structure later than driver-structure gives for-driver
helpers some trouble, when they are used by IOMMU driver assuming that the
new structure (including core) are fully initialized, for example:

core:	viommu = ops->viommu_alloc();
driver:	// my_viommu is successfully allocated
driver:	my_viommu = iommufd_viommu_alloc(...);
driver:	// This may crash if it reads viommu->ictx
driver:	new = iommufd_new_viommu_helper(my_viommu->core ...);
core:	viommu->ictx = ucmd->ictx;
core:	...

To ease such a condition, allow the IOMMU driver to report the size of its
vIOMMU structure, let the core allocate a vIOMMU object and initialize the
core-level structure first, and then hand it over the driver to initialize
its driver-level structure.

Thus, this requires two new iommu ops, get_viommu_size and viommu_init, so
iommufd core can communicate with drivers to replace the viommu_alloc op:

core:	viommu = ops->get_viommu_size();
driver:	return VIOMMU_STRUCT_SIZE();
core:	viommu->ictx = ucmd->ictx; // and others
core:	rc = ops->viommu_init();
driver:	// This is safe now as viommu->ictx is inited
driver:	new = iommufd_new_viommu_helper(my_viommu->core ...);
core:	...

This also adds a VIOMMU_STRUCT_SIZE macro, for drivers to use, which would
statically sanitize the driver structure.

Link: https://patch.msgid.link/r/3ab52c5b622dad476c43b1b1f1636c8b902f1692.1749882255.git.nicolinc@nvidia.com


Suggested-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Signed-off-by: default avatarNicolin Chen <nicolinc@nvidia.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Reviewed-by: default avatarLu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: default avatarKevin Tian <kevin.tian@intel.com>
Reviewed-by: default avatarPranjal Shrivastava <praan@google.com>
Signed-off-by: default avatarJason Gunthorpe <jgg@nvidia.com>
parent 0c6e0ae7

include/linux/iommu.h

+15 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/err.h>

#include <linux/of.h>

#include <linux/iova_bitmap.h>

#include <uapi/linux/iommufd.h>



#define IOMMU_READ	(1 << 0)

#define IOMMU_WRITE	(1 << 1)
@@ -596,6 +597,16 @@ iommu_copy_struct_from_full_user_array(void *kdst, size_t kdst_entry_size, 
 *		- IOMMU_DOMAIN_DMA: must use a dma domain

 *		- 0: use the default setting

 * @default_domain_ops: the default ops for domains

 * @get_viommu_size: Get the size of a driver-level vIOMMU structure for a given

 *                   @dev corresponding to @viommu_type. Driver should return 0

 *                   if vIOMMU isn't supported accordingly. It is required for

 *                   driver to use the VIOMMU_STRUCT_SIZE macro to sanitize the

 *                   driver-level vIOMMU structure related to the core one

 * @viommu_init: Init the driver-level struct of an iommufd_viommu on a physical

 *               IOMMU instance @viommu->iommu_dev, as the set of virtualization

 *               resources shared/passed to user space IOMMU instance. Associate

 *               it with a nesting @parent_domain. It is required for driver to

 *               set @viommu->ops pointing to its own viommu_ops

 * @viommu_alloc: Allocate an iommufd_viommu on a physical IOMMU instance behind

 *                the @dev, as the set of virtualization resources shared/passed

 *                to user space IOMMU instance. And associate it with a nesting
@@ -654,6 +665,10 @@ struct iommu_ops { 


	int (*def_domain_type)(struct device *dev);



	size_t (*get_viommu_size)(struct device *dev,

				  enum iommu_viommu_type viommu_type);

	int (*viommu_init)(struct iommufd_viommu *viommu,

			   struct iommu_domain *parent_domain);

	struct iommufd_viommu *(*viommu_alloc)(

		struct device *dev, struct iommu_domain *parent_domain,

		struct iommufd_ctx *ictx, unsigned int viommu_type);

include/linux/iommufd.h

+6 −0
Original line number Diff line number Diff line
@@ -229,6 +229,12 @@ static inline int iommufd_viommu_report_event(struct iommufd_viommu *viommu, 
}

#endif /* CONFIG_IOMMUFD_DRIVER_CORE */



#define VIOMMU_STRUCT_SIZE(drv_struct, member)                                 \

	(sizeof(drv_struct) +                                                  \

	 BUILD_BUG_ON_ZERO(offsetof(drv_struct, member)) +                     \

	 BUILD_BUG_ON_ZERO(!__same_type(struct iommufd_viommu,                 \

					((drv_struct *)NULL)->member)))



/*

 * Helpers for IOMMU driver to allocate driver structures that will be freed by

 * the iommufd core. The free op will be called prior to freeing the memory.