hwpmc: fix stopping process PMCs on exit with PerfMonV2HEADmain

Since 9d3064010590, pmc_process_exit() calls pmc_process_csw_stop_all()
first. That clears pps_cpustate for every virtual PMC on the CPU, so the
exit loop then skips the stop and the final read.

On AMD PerfMonV2 this has two effects:
- The count from the last time slice is lost. A process that never
  switches out before exit reports 0 with pmcstat -p.
- The EVSEL enable bit stays set. After kldunload, the next kldload
  sees it and says "PMCs maybe in use by firmware!".

It is not required that pmc_process_csw_stop_all() should touch the
ppc_cpustate field at all; remove this to fix the issues.

Reviewed by:	mhorne
Fixes:		9d3064010590 ("hwpmc_amd: add PerfMonV2 global-control path")
Sponsored by:	AMD
Differential Revision:	https://reviews.freebsd.org/D60141

0 files changed, 0 insertions, 0 deletions