tree 207b7e4df54669d1e39239f86498bb6cac3274a3
parent 7a6939bf55dd3340e711f9e964b40201a268bfeb
author Mark Brown <broonie@kernel.org> 1750252763 +0100
committer Mark Brown <broonie@kernel.org> 1750254513 +0100
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arm64/gcs: Don't try to access GCS registers if arm64.nogcs is enabled

During EL2 setup if GCS is advertised in the ID registers we will reset the
GCS control registers GCSCR_EL1 and GCSCRE0_EL1 to known values in order to
ensure it is disabled. This is done without taking into account overrides
supplied on the command line, meaning that if the user has configured
arm64.nogcs we will still access these GCS specific registers. If this was
done because EL3 does not enable GCS this results in traps to EL3 and a
failed boot which is not what users would expect from having set that
parameter.

Move the writes to these registers to finalise_el2_state where we can pay
attention to the command line overrides. For simplicity we leave the
updates to the traps in HCRX_EL2 and the FGT registers in place since these
should only be relevant for KVM guests and KVM will manage them itself for
guests. This follows the existing practice for other similar traps for
overridable features such as those for TPIDR2_EL0 and SMPRI_EL1.

Signed-off-by: Mark Brown <broonie@kernel.org>