perf/x86/amd: Add idle hooks for branch sampling

On AMD Fam19h Zen3, the branch sampling (BRS) feature must be disabled before
entering low power and re-enabled (if was active) when returning from low
power. Otherwise, the NMI interrupt may be held up for too long and cause
problems. Stopping BRS will cause the NMI to be delivered if it was held up.

Define a perf_amd_brs_lopwr_cb() callback to stop/restart BRS.  The callback
is protected by a jump label which is enabled only when AMD BRS is detected.
In all other cases, the callback is never called.

Signed-off-by: Stephane Eranian <eranian@google.com>
[peterz: static_call() and build fixes]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220322221517.2510440-10-eranian@google.com

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index ef27aee04b13..3b0324584da3 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -1226,6 +1226,7 @@ void amd_brs_enable(void);
 void amd_brs_enable_all(void);
 void amd_brs_disable_all(void);
 void amd_brs_drain(void);
+void amd_brs_lopwr_init(void);
 void amd_brs_disable_all(void);
 int amd_brs_setup_filter(struct perf_event *event);
 void amd_brs_reset(void);