[PATCH 4/7] perf, x86: implement IBS feature detection

[Robert Richter <robert.richter@amd.com>]

The new code checks if IBS is available on the cpu. It implements only
a basic detection that should be later extended to read ibs cpuid
feature flags.

Signed-off-by: Robert Richter <robert.richter@amd.com>
---
 arch/x86/kernel/cpu/perf_event.c     |    5 +++++
 arch/x86/kernel/cpu/perf_event_amd.c |    2 ++
 2 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index e64502c..e186d3b 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -244,6 +244,11 @@ struct x86_pmu {
 	 */
 	unsigned long	lbr_tos, lbr_from, lbr_to; /* MSR base regs       */
 	int		lbr_nr;			   /* hardware stack size */
+
+	/*
+	 * AMD IBS
+	 */
+	int		ibs;			/* cpuid flags */
 };
 
 static struct x86_pmu x86_pmu __read_mostly;
diff --git a/arch/x86/kernel/cpu/perf_event_amd.c b/arch/x86/kernel/cpu/perf_event_amd.c
index 87e5ae4..cda8475 100644
--- a/arch/x86/kernel/cpu/perf_event_amd.c
+++ b/arch/x86/kernel/cpu/perf_event_amd.c
@@ -405,6 +405,8 @@ static __init int amd_pmu_init(void)
 		return -ENODEV;
 
 	x86_pmu = amd_pmu;
+	if (boot_cpu_has(X86_FEATURE_IBS))
+		x86_pmu.ibs = 1;
 
 	/* Events are common for all AMDs */
 	memcpy(hw_cache_event_ids, amd_hw_cache_event_ids,
-- 
1.7.1