On Wed, Jun 16, 2021 at 01:09:49PM +0200, Aman Priyadarshi wrote: > 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> > ``` It does not apply cleanly so you will have to provide a working backport for us. > For more details: > > https://lists.cs.columbia.edu/pipermail/kvmarm/2021-June/047471.html lore.kernel.org is your friend :) thanks, greg k-h
