When pKVM is enabled, the hypervisor at EL2 does not trust the host at
EL1 and must therefore prevent it from having unrestricted access to
internal hypervisor state.

The 'kvm_arm_hyp_percpu_base' array holds the offsets for hypervisor
per-cpu allocations, so move this this into the nVHE code where it
cannot be modified by the untrusted host at EL1.
Tested-by: NVincent Donnefort <vdonnefort@google.com>
Signed-off-by: NQuentin Perret <qperret@google.com>
Signed-off-by: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221110190259.26861-22-will@kernel.org