1 files changed, 80 insertions, 0 deletions

diff --git a/recipes-kernel/linux/files/perf-x86-intel-Use-rdmsrl_safe-when-initializing-RAP.patch b/recipes-kernel/linux/files/perf-x86-intel-Use-rdmsrl_safe-when-initializing-RAP.patch
new file mode 100644
index 0000000..6b29970
--- /dev/null
+++ b/recipes-kernel/linux/files/perf-x86-intel-Use-rdmsrl_safe-when-initializing-RAP.patch
@@ -0,0 +1,80 @@
+From 24223657806a0ebd0ae5c9caaf7b021091889cf2 Mon Sep 17 00:00:00 2001
+From: Venkatesh Srinivas <venkateshs@google.com>
+Date: Thu, 13 Mar 2014 12:36:26 -0700
+Subject: [PATCH] perf/x86/intel: Use rdmsrl_safe() when initializing RAPL PMU
+
+CPUs which should support the RAPL counters according to
+Family/Model/Stepping may still issue #GP when attempting to access
+the RAPL MSRs. This may happen when Linux is running under KVM and
+we are passing-through host F/M/S data, for example. Use rdmsrl_safe
+to first access the RAPL_POWER_UNIT MSR; if this fails, do not
+attempt to use this PMU.
+
+Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
+Signed-off-by: Peter Zijlstra <peterz@infradead.org>
+Link: http://lkml.kernel.org/r/1394739386-22260-1-git-send-email-venkateshs@google.com
+Cc: zheng.z.yan@intel.com
+Cc: eranian@google.com
+Cc: ak@linux.intel.com
+Cc: linux-kernel@vger.kernel.org
+[ The patch also silently fixes another bug: rapl_pmu_init() didn't handle the memory alloc failure case previously. ]
+Signed-off-by: Ingo Molnar <mingo@kernel.org>
+Upstream-Status: Backport
+---
+ arch/x86/kernel/cpu/perf_event_intel_rapl.c | 12 +++++++++---
+ 1 file changed, 9 insertions(+), 3 deletions(-)
+
+diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+index 4b9a9e9..7c87424 100644
+--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
++++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+@@ -535,6 +535,7 @@ static int rapl_cpu_prepare(int cpu)
+        struct rapl_pmu *pmu = per_cpu(rapl_pmu, cpu);
+        int phys_id = topology_physical_package_id(cpu);
+        u64 ms;
++       u64 msr_rapl_power_unit_bits;
+ 
+        if (pmu)
+                return 0;
+@@ -542,6 +543,9 @@ static int rapl_cpu_prepare(int cpu)
+        if (phys_id < 0)
+                return -1;
+ 
++       if (!rdmsrl_safe(MSR_RAPL_POWER_UNIT, &msr_rapl_power_unit_bits))
++               return -1;
++
+        pmu = kzalloc_node(sizeof(*pmu), GFP_KERNEL, cpu_to_node(cpu));
+        if (!pmu)
+                return -1;
+@@ -555,8 +559,7 @@ static int rapl_cpu_prepare(int cpu)
+         *
+         * we cache in local PMU instance
+         */
+-       rdmsrl(MSR_RAPL_POWER_UNIT, pmu->hw_unit);
+-       pmu->hw_unit = (pmu->hw_unit >> 8) & 0x1FULL;
++       pmu->hw_unit = (msr_rapl_power_unit_bits >> 8) & 0x1FULL;
+        pmu->pmu = &rapl_pmu_class;
+ 
+        /*
+@@ -677,7 +680,9 @@ static int __init rapl_pmu_init(void)
+        cpu_notifier_register_begin();
+ 
+        for_each_online_cpu(cpu) {
+-               rapl_cpu_prepare(cpu);
++               ret = rapl_cpu_prepare(cpu);
++               if (ret)
++                       goto out;
+                rapl_cpu_init(cpu);
+        }
+ 
+@@ -700,6 +705,7 @@ static int __init rapl_pmu_init(void)
+                hweight32(rapl_cntr_mask),
+                ktime_to_ms(pmu->timer_interval));
+ 
++out:
+        put_online_cpus();
+ 
+        return 0;
+-- 
+1.9.0
+