[PATCH 2/5] perf, amd: Use GO/HO bits in perf-ctr

Joerg Roedel
2011-06-17T13:37:31Z

The AMD perf-counters support counting in guest or host-mode
only. Make use of that feature when user-space specified
guest/host-mode only counting.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
---
arch/x86/include/asm/perf_event.h | 3 +++
arch/x86/kernel/cpu/perf_event_amd.c | 13 +++++++++++++
2 files changed, 16 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index d9d4dae..34047c2 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -29,6 +29,9 @@
#define ARCH_PERFMON_EVENTSEL_INV (1ULL << 23)
#define ARCH_PERFMON_EVENTSEL_CMASK 0xFF000000ULL

+#define AMD_PERFMON_EVENTSEL_GUESTONLY (1ULL << 40)
+#define AMD_PERFMON_EVENTSEL_HOSTONLY (1ULL << 41)
+
#define AMD64_EVENTSEL_EVENT \
(ARCH_PERFMON_EVENTSEL_EVENT | (0x0FULL << 32))
#define INTEL_ARCH_EVENT_MASK \
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index fe29c1d..66809e7 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -118,6 +118,19 @@ static int amd_pmu_hw_config(struct perf_event *event)
if (ret)
return ret;

+ if (event->attr.exclude_host && event->attr.exclude_guest)
+ /*
+ * When HO == GO == 1 the hardware treats that as GO == HO == 0
+ * and will count in both modes. We don't want to count in that
+ * case so we emulate no-counting by setting US = OS = 0.
+ */
+ event->hw.config &= ~(ARCH_PERFMON_EVENTSEL_USR |
+ ARCH_PERFMON_EVENTSEL_OS);
+ else if (event->attr.exclude_host)
+ event->hw.config |= AMD_PERFMON_EVENTSEL_GUESTONLY;
+ else if (event->attr.exclude_guest)
+ event->hw.config |= AMD_PERFMON_EVENTSEL_HOSTONLY;
+
if (event->attr.type != PERF_TYPE_RAW)
return 0;

--
1.7.4.1