373beef00f
When SVE is enabled, the host may set bit 16 in SMCCC function IDs, a
hint that indicates an unused SVE state. At the moment NVHE doesn't
account for this bit when inspecting the function ID, and rejects most
calls. Clear the hint bit before comparing function IDs.
About version compatibility: the host's PSCI driver initially probes the
firmware for a SMCCC version number. If the firmware implements a
protocol recent enough (1.3), subsequent SMCCC calls have the hint bit
set. Since the hint bit was reserved in earlier versions of the
protocol, clearing it is fine regardless of the version in use.
When a new hint is added to the protocol in the future, it will be added
to ARM_SMCCC_CALL_HINTS and NVHE will handle it straight away. This
patch only clears known hints and leaves reserved bits as is, because
future SMCCC versions could use reserved bits as modifiers for the
function ID, rather than hints.
Fixes: cfa7ff959a78 ("arm64: smccc: Support SMCCC v1.3 SVE register saving hint")
Reported-by: Ben Horgan <ben.horgan@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230911145254.934414-4-jean-philippe@linaro.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.