98b8a550da
[ Upstream commit bb57f6705960bebeb832142ce9abf43220c3eab1 ]
When the bootloader/firmware doesn't setup the framebuffers, their
address and size are 0 in "iommu-addresses" property. If IOVA region is
reserved with 0 length, then it ends up corrupting the IOVA rbtree with
an entry which has pfn_hi < pfn_lo.
If we intend to use display driver in kernel without framebuffer then
it's causing the display IOMMU mappings to fail as entire valid IOVA
space is reserved when address and length are passed as 0.
An ideal solution would be firmware removing the "iommu-addresses"
property and corresponding "memory-region" if display is not present.
But the kernel should be able to handle this by checking for size of
IOVA region and skipping the IOVA reservation if size is 0. Also, add
a warning if firmware is requesting 0-length IOVA region reservation.
Fixes: a5bf3cfce8cb ("iommu: Implement of_iommu_get_resv_regions()")
Signed-off-by: Ashish Mhetre <amhetre@nvidia.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20231205065656.9544-1-amhetre@nvidia.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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 Restructured Text 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.