linux-kernel - [PATCH] perf/x86/intel: Fix unchecked MSR access error for Alder Lake N

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Message-Id: <20220621181628.381523-1-kan.liang@linux.intel.com>
Date:   Tue, 21 Jun 2022 11:16:28 -0700
From:   kan.liang@...ux.intel.com
To:     peterz@...radead.org, mingo@...hat.com,
        linux-kernel@...r.kernel.org
Cc:     alexander.shishkin@...ux.intel.com, ak@...ux.intel.com,
        Kan Liang <kan.liang@...ux.intel.com>, Gao@...r.kernel.org,
        Jianfeng <jianfeng.gao@...el.com>
Subject: [PATCH] perf/x86/intel: Fix unchecked MSR access error for Alder Lake N

From: Kan Liang <kan.liang@...ux.intel.com>

For some Alder Lake N machine, the below unchecked MSR access error may be
triggered.

[ 0.088017] rcu: Hierarchical SRCU implementation.
[ 0.088017] unchecked MSR access error: WRMSR to 0x38f (tried to write
0x0001000f0000003f) at rIP: 0xffffffffb5684de8 (native_write_msr+0x8/0x30)
[ 0.088017] Call Trace:
[ 0.088017] <TASK>
[ 0.088017] __intel_pmu_enable_all.constprop.46+0x4a/0xa0

The Alder Lake N only has e-cores. The X86_FEATURE_HYBRID_CPU flag is
not set. The perf cannot retrieve the correct CPU type via
get_this_hybrid_cpu_type(). The model specific get_hybrid_cpu_type() is
hardcode to p-core. The wrong CPU type is given to the PMU of the
Alder Lake N.

Add a model check to return the e-core CPU type for Alder Lake N.

Factor out x86_pmu_get_this_hybrid_cpu_type().

Fixes: c2a960f7c574 ("perf/x86: Add new Alder Lake and Raptor Lake support")
Reported-by: Gao, Jianfeng <jianfeng.gao@...el.com>
Tested-by: Gao, Jianfeng <jianfeng.gao@...el.com>
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 arch/x86/events/core.c       | 15 +++++++++++----
 arch/x86/events/intel/core.c |  8 ++++----
 arch/x86/events/perf_event.h |  2 ++
 3 files changed, 17 insertions(+), 8 deletions(-)

diff --git a/arch/x86/events/core.c b/arch/x86/events/core.c
index 0b19ffaa2dee..94cdf7e76b86 100644
--- a/arch/x86/events/core.c
+++ b/arch/x86/events/core.c
@@ -2076,6 +2076,16 @@ void x86_pmu_update_cpu_context(struct pmu *pmu, int cpu)
 	cpuctx->ctx.pmu = pmu;
 }
 
+u8 x86_pmu_get_this_hybrid_cpu_type(void)
+{
+	u8 cpu_type = get_this_hybrid_cpu_type();
+
+	if (!cpu_type && x86_pmu.get_hybrid_cpu_type)
+		return x86_pmu.get_hybrid_cpu_type();
+
+	return cpu_type;
+}
+
 static int __init init_hw_perf_events(void)
 {
 	struct x86_pmu_quirk *quirk;
@@ -2175,13 +2185,10 @@ static int __init init_hw_perf_events(void)
 		if (err)
 			goto out2;
 	} else {
-		u8 cpu_type = get_this_hybrid_cpu_type();
+		u8 cpu_type = x86_pmu_get_this_hybrid_cpu_type();
 		struct x86_hybrid_pmu *hybrid_pmu;
 		int i, j;
 
-		if (!cpu_type && x86_pmu.get_hybrid_cpu_type)
-			cpu_type = x86_pmu.get_hybrid_cpu_type();
-
 		for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
 			hybrid_pmu = &x86_pmu.hybrid_pmu[i];
 
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c
index 217c5695cbb0..1d57cf0be806 100644
--- a/arch/x86/events/intel/core.c
+++ b/arch/x86/events/intel/core.c
@@ -4267,6 +4267,9 @@ static int adl_hw_config(struct perf_event *event)
 
 static u8 adl_get_hybrid_cpu_type(void)
 {
+	if (boot_cpu_data.x86_model == INTEL_FAM6_ALDERLAKE_N)
+		return hybrid_small;
+
 	return hybrid_big;
 }
 
@@ -4430,13 +4433,10 @@ static void flip_smm_bit(void *data)
 static bool init_hybrid_pmu(int cpu)
 {
 	struct cpu_hw_events *cpuc = &per_cpu(cpu_hw_events, cpu);
-	u8 cpu_type = get_this_hybrid_cpu_type();
+	u8 cpu_type = x86_pmu_get_this_hybrid_cpu_type();
 	struct x86_hybrid_pmu *pmu = NULL;
 	int i;
 
-	if (!cpu_type && x86_pmu.get_hybrid_cpu_type)
-		cpu_type = x86_pmu.get_hybrid_cpu_type();
-
 	for (i = 0; i < x86_pmu.num_hybrid_pmus; i++) {
 		if (x86_pmu.hybrid_pmu[i].cpu_type == cpu_type) {
 			pmu = &x86_pmu.hybrid_pmu[i];
diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
index ba30f24bec41..c1bf7e6af6a0 100644
--- a/arch/x86/events/perf_event.h
+++ b/arch/x86/events/perf_event.h
@@ -1176,6 +1176,8 @@ void x86_pmu_show_pmu_cap(int num_counters, int num_counters_fixed,
 
 void x86_pmu_update_cpu_context(struct pmu *pmu, int cpu);
 
+u8 x86_pmu_get_this_hybrid_cpu_type(void);
+
 extern struct event_constraint emptyconstraint;
 
 extern struct event_constraint unconstrained;
-- 
2.35.1