This capability gives us the ability to open PERF_TYPE_HARDWARE and
PERF_TYPE_HW_CACHE events on a specific PMU for free. All the
implementation is contained in the Perf core and tool code so no change
to the Arm PMU driver is needed.

The following basic use case now results in Perf opening the event on
all PMUs rather than picking only one in an unpredictable way:

  $ perf stat -e cycles -- taskset --cpu-list 0,1 stress -c 2

   Performance counter stats for 'taskset --cpu-list 0,1 stress -c 2':

         963279620      armv8_cortex_a57/cycles/                (99.19%)
         752745657      armv8_cortex_a53/cycles/                (94.80%)

Fixes: 55bcf6ef ("perf: Extend PERF_TYPE_HARDWARE and PERF_TYPE_HW_CACHE")
Suggested-by: Ian Rogers <irogers@google.com>
Signed-off-by: James Clark <james.clark@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20230724134500.970496-2-james.clark@arm.com