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iommu: Introduce get_viommu_size and viommu_init ops

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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: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Pranjal Shrivastava <praan@google.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Nicolin Chen 2025-06-13 23:35:18 -07:00 committed by Jason Gunthorpe
parent 0c6e0ae7a7
commit 187f146d5d
2 changed files with 21 additions and 0 deletions
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15
include/linux/iommu.h
View File

@ -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);

6
include/linux/iommufd.h
View File

@ -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.