[PATCH v3] perf: xgene: Add CPU hotplug support

[will.deacon@arm.com (Will Deacon)]

On Wed, Nov 21, 2018 at 04:08:14PM +0000, Mark Rutland wrote:
> On Wed, Nov 07, 2018 at 07:40:58PM +0000, Hoan Tran wrote:
> > From: Hoan Tran <Hoan@os.amperecomputing.com>
> > 
> > This patch adds CPU hotplug support where the PMU migrates the context to
> > another online CPU when its CPU is offline.
> > 
> > It fixes the below issue where the user does offline the CPU which is assigned
> > to this PMU.
> > 
> > Assuming, CPU0 is assigned for this PMU. When the user does offline CPU0
> > 	[root@(none) ~]# echo 0 > /sys/devices/system/cpu/cpu0/online
> > This PMU does not work anymore and shows the below error.
> > 	[root@(none) ~]# perf stat -a -e l3c0/cycle-count/,l3c0/write/ sleep 1
> > 	Error:
> > 	The sys_perf_event_open() syscall returned with 19 (No such device) for event (l3c0/cycle-count/).
> > 	/bin/dmesg may provide additional information.
> > 	No CONFIG_PERF_EVENTS=y kernel support configured?
> > 
> > With this patch, when CPU0 is offline, PMU migrates to another online CPU and
> > works on that CPU.
> > 
> > Signed-off-by: Hoan Tran <hoan.tran@amperecomputing.com>
> > ---
> > v3:
> >  * Remove email footer
> >  * Fix the space issue
> > 
> > v2:
> >  * Remove the cpuhp instance when unregistering the PMU
> 
> Aside from one minor fixup below, this looks good to me, and with that
> applied:
> 
> Acked-by: Mark Rutland <mark.rutland@arm.com>
> 
> Will, are you happy to apply that fixup when picking the patch?

Thanks, Mark. I'll queue this up and fix the naming of the enum entry.

Will