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[ Upstream commit 5583a55e074b33ccd88ac0542fd7cd656a7e2c8c ] Some platforms (e.g. SC8280XP and X1E) support more than 128 stream matching groups. This is more than what is defined as maximum by the ARM SMMU architecture specification. Commit1226113473("iommu/arm-smmu-qcom: Limit the SMR groups to 128") disabled use of the additional groups because they don't exhibit the same behavior as the architecture supported ones. It seems like this is just another quirk of the hypervisor: When running bare-metal without the hypervisor, the additional groups appear to behave just like all others. The boot firmware uses some of the additional groups, so ignoring them in this situation leads to stream match conflicts whenever we allocate a new SMR group for the same SID. The workaround exists primarily because the bypass quirk detection fails when using a S2CR register from the additional matching groups, so let's perform the test with the last reliable S2CR (127) and then limit the number of SMR groups only if we detect that we are running below the hypervisor (because of the bypass quirk). Fixes:1226113473("iommu/arm-smmu-qcom: Limit the SMR groups to 128") Signed-off-by: Stephan Gerhold <stephan.gerhold@linaro.org> Signed-off-by: Will Deacon <will@kernel.org> 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.