1 files changed, 29 insertions, 0 deletions

diff --git a/recipes-kernel/linux/files/perf-x86-fix-RAPL-rdmsrl_safe-usage.patch b/recipes-kernel/linux/files/perf-x86-fix-RAPL-rdmsrl_safe-usage.patch
new file mode 100644
index 0000000..058e676
--- /dev/null
+++ b/recipes-kernel/linux/files/perf-x86-fix-RAPL-rdmsrl_safe-usage.patch
@@ -0,0 +1,29 @@
+From: Stephane Eranian
+Date: Wed Apr 23 2014 - 13:04:31 EST
+This patch fixes a bug introduced by commit 24223657.
+
+perf/x86: fix RAPL rdmsrl_safe() usage
+
+The rdmsrl_safe() function returns 0 on success.
+The current code was failing to detect the RAPL PMU
+on real hardware (missing /sys/devices/power) because
+the return value of rdmsrl_safe() was misinterpreted.
+
+Signed-off-by: Stephane Eranian <eranian@xxxxxxxxxx>
+Upstream-Status: Backport [http://lkml.iu.edu/hypermail/linux/kernel/1404.2/05008.html]
+
+diff --git a/arch/x86/kernel/cpu/perf_event_intel_rapl.c b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+index 7c87424..619f769 100644
+--- a/arch/x86/kernel/cpu/perf_event_intel_rapl.c
++++ b/arch/x86/kernel/cpu/perf_event_intel_rapl.c
+@@ -543,7 +543,8 @@ 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))
++       /* protect rdmsrl() to handle virtualization */
++       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));
+--