Ionela Voinescu writes:

The activity monitors extension is an optional extension introduced
by the ARMv8.4 CPU architecture. This implements basic support for
version 1 of the activity monitors architecture, AMUv1.

This support includes:
- Extension detection on each CPU (boot, secondary, hotplugged)
- Register interface for AMU aarch64 registers
- amu=[0/1/on/off/y/n] kernel parameter to disable detection and
  counter access at runtime

Signed-off-by: Ionela Voinescu <redacted>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>

Reviewed-by: Valentin Schneider <redacted>