Jason Gunthorpe b3efacc451 iommu/pages: Allow sub page sizes to be passed into the allocator
Generally drivers have a specific idea what their HW structure size should
be. In a lot of cases this is related to PAGE_SIZE, but not always. ARM64,
for example, allows a 4K IO page table size on a 64K CPU page table
system.

Currently we don't have any good support for sub page allocations, but
make the API accommodate this by accepting a sub page size from the caller
and rounding up internally.

This is done by moving away from order as the size input and using size:
  size == 1 << (order + PAGE_SHIFT)

Following patches convert drivers away from using order and try to specify
allocation sizes independent of PAGE_SIZE.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Tested-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Tested-by: Nicolin Chen <nicolinc@nvidia.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/15-v4-c8663abbb606+3f7-iommu_pages_jgg@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
2025-04-17 16:22:46 +02:00
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2025-04-06 10:00:04 -07:00
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2025-04-13 11:54:49 -07:00
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Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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