df466a61f6
[ Upstream commit d80f6de9d601c30b53c17f00cb7cfe3169f2ddad ]
The existing iommu_table_in_use() helper checks if the kernel is using
any of TCEs. There are some reserved TCEs:
1) the very first one if DMA window starts from 0 to avoid having a zero
but still valid DMA handle;
2) it_reserved_start..it_reserved_end to exclude MMIO32 window in case
the default window spans across that - this is the default for the first
DMA window on PowerNV.
When 1) is the case and 2) is not the helper does not skip 1) and returns
wrong status.
This only seems occurring when passing through a PCI device to a nested
guest (not something we support really well) so it has not been seen
before.
This fixes the bug by adding a special case for no MMIO32 reservation.
Fixes: 3c33066a2190 ("powerpc/kernel/iommu: Add new iommu_table_in_use() helper")
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220714081119.3714605-1-aik@ozlabs.ru
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.