perf counters: protect them against CSTATE transitions

Impact: fix rare lost events problem

There are CPUs whose performance counters misbehave on CSTATE transitions,
so provide a way to just disable/enable them around deep idle methods.

(hw_perf_enable_all() is cheap on x86.)

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 5f8d746a9b81..cca804e6f1dd 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -270,8 +270,11 @@ static atomic_t c3_cpu_count;
 /* Common C-state entry for C2, C3, .. */
 static void acpi_cstate_enter(struct acpi_processor_cx *cstate)
 {
+        u64 pctrl;
+
         /* Don't trace irqs off for idle */
         stop_critical_timings();
+        pctrl = hw_perf_disable_all();
         if (cstate->entry_method == ACPI_CSTATE_FFH) {
                 /* Call into architectural FFH based C-state */
                 acpi_processor_ffh_cstate_enter(cstate);
@@ -284,6 +287,7 @@ static void acpi_cstate_enter(struct acpi_processor_cx *cstate)
                    gets asserted in time to freeze execution properly. */
                 unused = inl(acpi_gbl_FADT.xpm_timer_block.address);
         }
+        hw_perf_restore_ctrl(pctrl);
         start_critical_timings();
 }
 #endif /* !CONFIG_CPU_IDLE */
@@ -1425,8 +1429,11 @@ static inline void acpi_idle_update_bm_rld(struct acpi_processor *pr,
  */
 static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
 {
+        u64 pctrl;
+
         /* Don't trace irqs off for idle */
         stop_critical_timings();
+        pctrl = hw_perf_disable_all();
         if (cx->entry_method == ACPI_CSTATE_FFH) {
                 /* Call into architectural FFH based C-state */
                 acpi_processor_ffh_cstate_enter(cx);
@@ -1441,6 +1448,7 @@ static inline void acpi_idle_do_entry(struct acpi_processor_cx *cx)
                    gets asserted in time to freeze execution properly. */
                 unused = inl(acpi_gbl_FADT.xpm_timer_block.address);
         }
+        hw_perf_restore_ctrl(pctrl);
         start_critical_timings();
 }