KVM: arm64: nv: Accelerate EL0 counter accesses from hypervisor context

Similarly to handling the physical timer accesses early when FEAT_ECV
causes a trap, we try to handle the physical counter without returning
to the general sysreg handling.

More surprisingly, we introduce something similar for the virtual
counter. Although this isn't necessary yet, it will prove useful on
systems that have a broken CNTVOFF_EL2 implementation. Yes, they exist.

Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241217142321.763801-7-maz@kernel.org


Signed-off-by: Marc Zyngier <maz@kernel.org>