linux-kernel - Re: [PATCHv2 6/9] perf: expose perf capability to other modules.

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Message-ID: <1320758811.11519.1.camel@twins>
Date:	Tue, 08 Nov 2011 14:26:51 +0100
From:	Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	Gleb Natapov <gleb@...hat.com>
Cc:	kvm@...r.kernel.org, avi@...hat.com, mtosatti@...hat.com,
	linux-kernel@...r.kernel.org, mingo@...e.hu,
	acme@...stprotocols.net
Subject: Re: [PATCHv2 6/9] perf: expose perf capability to other modules.

On Tue, 2011-11-08 at 14:49 +0200, Gleb Natapov wrote:
> > It might make sense to introduce cpuid10_ebx or so, also I think the
> cpuid10_ebx will have only one field though (event_mask).
> 
> > At the very least add a full ebx iteration to disable unsupported events
> > in the intel-v1 case.
> I do not understand what do you mean here, cpuid10_ebx was introduced by
> intel v1 architectural PMU so it should already contain correct information.

I meant something like the below

---
 arch/x86/include/asm/perf_event.h      |   13 +++++++++++++
 arch/x86/kernel/cpu/perf_event.c       |    3 +++
 arch/x86/kernel/cpu/perf_event_intel.c |   21 ++++++++++++++++++---
 3 files changed, 34 insertions(+), 3 deletions(-)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index f61c62f..98e397a 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -72,6 +72,19 @@ union cpuid10_eax {
 	unsigned int full;
 };
 
+union cpuid10_ebx {
+	struct {
+		unsigned int unhalted_core_cycles:1;
+		unsigned int instructions_retired:1;
+		unsigned int unhalted_reference_cycles:1;
+		unsigned int llc_reference:1;
+		unsigned int llc_misses:1;
+		unsigned int branch_instruction_retired:1;
+		unsigned int branch_misses_retired:1;
+	} split;
+	unsigned int full;
+};
+
 union cpuid10_edx {
 	struct {
 		unsigned int num_counters_fixed:5;
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 6408910..e4fdb9d 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -336,6 +336,9 @@ int x86_setup_perfctr(struct perf_event *event)
 	if (config == -1LL)
 		return -EINVAL;
 
+	if (config == -2LL)
+		return -EOPNOTSUPP;
+
 	/*
 	 * Branch tracing:
 	 */
diff --git a/arch/x86/kernel/cpu/perf_event_intel.c b/arch/x86/kernel/cpu/perf_event_intel.c
index e09ca20..aaaed9a 100644
--- a/arch/x86/kernel/cpu/perf_event_intel.c
+++ b/arch/x86/kernel/cpu/perf_event_intel.c
@@ -1547,9 +1547,9 @@ static void intel_clovertown_quirks(void)
 __init int intel_pmu_init(void)
 {
 	union cpuid10_edx edx;
+	union cpuid10_ebx ebx;
 	union cpuid10_eax eax;
 	unsigned int unused;
-	unsigned int ebx;
 	int version;
 
 	if (!cpu_has(&boot_cpu_data, X86_FEATURE_ARCH_PERFMON)) {
@@ -1566,7 +1566,7 @@ __init int intel_pmu_init(void)
 	 * Check whether the Architectural PerfMon supports
 	 * Branch Misses Retired hw_event or not.
 	 */
-	cpuid(10, &eax.full, &ebx, &unused, &edx.full);
+	cpuid(10, &eax.full, &ebx.full, &unused, &edx.full);
 	if (eax.split.mask_length <= ARCH_PERFMON_BRANCH_MISSES_RETIRED)
 		return -ENODEV;
 
@@ -1598,6 +1598,21 @@ __init int intel_pmu_init(void)
 		x86_pmu.intel_cap.capabilities = capabilities;
 	}
 
+	if (!ebx.split.unhalted_core_cycles)
+		intel_perfmon_event_map[PERF_COUNT_HW_CPU_CYCLES] = -2;
+	if (!ebx.split.instructions_retired)
+		intel_perfmon_event_map[PERF_COUNT_HW_INSTRUCTIONS] = -2;
+	if (!ebx.split.unhalted_reference_cycles)
+		intel_perfmon_event_map[PERF_COUNT_HW_BUS_CYCLES] = -2;
+	if (!ebx.split.llc_reference)
+		intel_perfmon_event_map[PERF_COUNT_HW_CACHE_REFERENCES] = -2;
+	if (!ebx.split.llc_misses)
+		intel_perfmon_event_map[PERF_COUNT_HW_CACHE_MISSES] = -2;
+	if (!ebx.split.branch_instruction_retired)
+		intel_perfmon_event_map[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = -2;
+	if (!ebx.split.branch_misses_retired)
+		intel_perfmon_event_map[PERF_COUNT_HW_BRANCH_MISSES] = -2;
+
 	intel_ds_init();
 
 	/*
@@ -1643,7 +1658,7 @@ __init int intel_pmu_init(void)
 		/* UOPS_EXECUTED.CORE_ACTIVE_CYCLES,c=1,i=1 */
 		intel_perfmon_event_map[PERF_COUNT_HW_STALLED_CYCLES_BACKEND] = 0x1803fb1;
 
-		if (ebx & 0x40) {
+		if (ebx.split.branch_misses_retired) {
 			/*
 			 * Erratum AAJ80 detected, we work it around by using
 			 * the BR_MISP_EXEC.ANY event. This will over-count

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