Hi Greg,
Following the conversation with Marc, we discovered that an
important fix for ARM PMU is not backported to 4.14.y tree, it affects
counter value and give out nonsensical result.
Can you please include the following commit?
```
commit 3cce50dfec4a5b0414c974190940f47dd32c6dee
Author: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Date: Tue Jul 10 09:58:03 2018 +0100
arm64: perf: Disable PMU while processing counter overflows
The arm64 PMU updates the event counters and reprograms the
counters in the overflow IRQ handler without disabling the
PMU. This could potentially cause skews in for group counters,
where the overflowed counters may potentially loose some event
counts, while they are reprogrammed. To prevent this, disable
the PMU while we process the counter overflows and enable it
right back when we are done.
This patch also moves the PMU stop/start routines to avoid a
forward declaration.
Suggested-by: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
```
For more details:
https://lists.cs.columbia.edu/pipermail/kvmarm/2021-June/047471.html
Regards,
Aman Priyadarshi
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
