Alexey Kardashevskiy fc3db7fbdf swiotlb: reduce the swiotlb buffer size on allocation failure
[ Upstream commit 8d58aa4849 ]

At the moment the AMD encrypted platform reserves 6% of RAM for SWIOTLB
or 1GB, whichever is less. However it is possible that there is no block
big enough in the low memory which make SWIOTLB allocation fail and
the kernel continues without DMA. In such case a VM hangs on DMA.

This moves alloc+remap to a helper and calls it from a loop where
the size is halved on each iteration.

This updates default_nslabs on successful allocation which looks like
an oversight as not doing so should have broken callers of
swiotlb_size_or_default().

Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Stable-dep-of: 8ac0406335 ("swiotlb: reduce the number of areas to match actual memory pool size")
Signed-off-by: Sasha Levin <sashal@kernel.org>
2023-07-23 13:49:19 +02:00
2023-07-19 16:22:12 +02:00
2023-07-19 16:22:16 +02:00
2023-07-19 16:21:44 +02:00
2022-09-28 09:02:20 +02:00
2022-09-28 09:02:20 +02:00
2023-07-19 16:22:18 +02:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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    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.
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