BACKPORT: KVM: arm64: Move SPE availability check to VCPU load

At the moment, we check the availability of SPE on the given
CPU (i.e, SPE is implemented and is allowed at the host) during
every guest entry. This can be optimized a bit by moving the
check to vcpu_load time and recording the availability of the
feature on the current CPU via a new flag. This will also be useful
for adding the TRBE support.

Bug: 174685394
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Alexandru Elisei <Alexandru.Elisei@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210405164307.1720226-7-suzuki.poulose@arm.com


Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
(cherry picked from commit d2602bb4)
[Conflict in: arch/arm64/kvm/hyp/nvhe/debug-sr.c
Trivial conflict because of an additional __debug_save_trace() call
since a previous version of the series was backported already.]
Signed-off-by: Qais Yousef <qais.yousef@arm.com>
Change-Id: I4ca2bb14f7b647a1e118ea4a8c4313154a482685