Re: [PATCH v3 0/7] arm64: Add support for Armv9.4 PMU fixed instruction counter

[James Clark]

On 31/07/2024 5:51 pm, Rob Herring (Arm) wrote:
> This series adds support for the optional fixed instruction counter
> added in Armv9.4 PMU. Most of the series is a refactoring to remove the
> index to counter number conversion which dates back to the Armv7 PMU
> driver. Removing it is necessary in order to support more than 32
> counters without a bunch of conditional code further complicating the
> conversion.
>
> Patch 1 changes struct arm_pmu.num_events to a bitmap of events, and
> updates all the users. This removes the index to counter conversion
> on the PMUv3 and Armv7 drivers.
>
> Patch 2 updates various register accessors to use 64-bit values matching
> the register size.
>
> Patches 3-4 update KVM PMU register accesses to use shared accessors
> from asm/arm_pmuv3.h.
>
> Patches 5-6 rework KVM and perf PMU defines for counter indexes and
> number of counters.
>
> Patch 7 finally adds support for the fixed instruction counter.
>
> I tested this on FVP with VHE host and a guest. Also ran kvm-unittests
> in Arm's kernelCI.

I ran the Perf tests and poked around a bit with PMUs and chaining 
events (on non-fixed instruction counter hardware):

Tested-by: James Clark <james.clark@xxxxxxxxxx>