perf/x86/intel/uncore: Fix boot crash on SBOX PMU on Haswell-EP

There were several reports that on some systems writing the SBOX0 PMU
initialization MSR would #GP at boot. This did not happen on all
systems -- my two test systems booted fine.

Writing the three initialization bits bit-by-bit seems to avoid the
problem. So add a special callback to do just that.

This replaces an earlier patch that disabled the SBOX.

Reported-by: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Reported-and-Tested-by: Patrick Lu <patrick.lu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Link: http://lkml.kernel.org/r/1415062828-19759-4-git-send-email-andi@firstfloor.org
[ Fixed a whitespace error and added attribution tags that were left out inexplicably. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 30 insertions, 3 deletions

diff --git a/arch/x86/kernel/cpu/perf_event_intel_uncore_snbep.c b/arch/x86/kernel/cpu/perf_event_intel_uncore_snbep.c
index 0af1c932fa0f..f9ed429d6e4f 100644
--- a/arch/x86/kernel/cpu/perf_event_intel_uncore_snbep.c
+++ b/arch/x86/kernel/cpu/perf_event_intel_uncore_snbep.c
@@ -486,14 +486,17 @@ static struct attribute_group snbep_uncore_qpi_format_group = {
         .attrs = snbep_uncore_qpi_formats_attr,
 };
 
-#define SNBEP_UNCORE_MSR_OPS_COMMON_INIT()                      \
-        .init_box       = snbep_uncore_msr_init_box,            \
+#define __SNBEP_UNCORE_MSR_OPS_COMMON_INIT()                    \
         .disable_box    = snbep_uncore_msr_disable_box,         \
         .enable_box     = snbep_uncore_msr_enable_box,          \
         .disable_event  = snbep_uncore_msr_disable_event,       \
         .enable_event   = snbep_uncore_msr_enable_event,        \
         .read_counter   = uncore_msr_read_counter
 
+#define SNBEP_UNCORE_MSR_OPS_COMMON_INIT()                      \
+        __SNBEP_UNCORE_MSR_OPS_COMMON_INIT(),                   \
+        .init_box       = snbep_uncore_msr_init_box             \
+
 static struct intel_uncore_ops snbep_uncore_msr_ops = {
         SNBEP_UNCORE_MSR_OPS_COMMON_INIT(),
 };
@@ -1919,6 +1922,30 @@ static struct intel_uncore_type hswep_uncore_cbox = {
         .format_group           = &hswep_uncore_cbox_format_group,
 };
 
+/*
+ * Write SBOX Initialization register bit by bit to avoid spurious #GPs
+ */
+static void hswep_uncore_sbox_msr_init_box(struct intel_uncore_box *box)
+{
+        unsigned msr = uncore_msr_box_ctl(box);
+
+        if (msr) {
+                u64 init = SNBEP_PMON_BOX_CTL_INT;
+                u64 flags = 0;
+                int i;
+
+                for_each_set_bit(i, (unsigned long *)&init, 64) {
+                        flags |= (1ULL << i);
+                        wrmsrl(msr, flags);
+                }
+        }
+}
+
+static struct intel_uncore_ops hswep_uncore_sbox_msr_ops = {
+        __SNBEP_UNCORE_MSR_OPS_COMMON_INIT(),
+        .init_box               = hswep_uncore_sbox_msr_init_box
+};
+
 static struct attribute *hswep_uncore_sbox_formats_attr[] = {
         &format_attr_event.attr,
         &format_attr_umask.attr,
@@ -1944,7 +1971,7 @@ static struct intel_uncore_type hswep_uncore_sbox = {
         .event_mask             = HSWEP_S_MSR_PMON_RAW_EVENT_MASK,
         .box_ctl                = HSWEP_S0_MSR_PMON_BOX_CTL,
         .msr_offset             = HSWEP_SBOX_MSR_OFFSET,
-        .ops                    = &snbep_uncore_msr_ops,
+        .ops                    = &hswep_uncore_sbox_msr_ops,
         .format_group           = &hswep_uncore_sbox_format_group,
 };