To work around or debug split lock issues, the kernel parameter
"nosplit_lock_detect" is introduced to disable the feature during boot
time.
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
.../admin-guide/kernel-parameters.txt | 2 ++
arch/x86/kernel/cpu/intel.c | 25 ++++++++++++++++---
2 files changed, 23 insertions(+), 4 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2b8ee90bb644..623a5f223ff1 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3019,6 +3019,8 @@
nosoftlockup [KNL] Disable the soft-lockup detector.
+ nosplit_lock_detect [X86] Disable split lock detection
+
nosync [HW,M68K] Disables sync negotiation for all devices.
nowatchdog [KNL] Disable both lockup detectors, i.e.
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 28cc6891ba48..959ebf25beda 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -19,6 +19,7 @@
#include <asm/microcode_intel.h>
#include <asm/hwcap2.h>
#include <asm/elf.h>
+#include <asm/cmdline.h>
#ifdef CONFIG_X86_64
#include <linux/topology.h>
@@ -34,6 +35,8 @@
DEFINE_PER_CPU(u64, msr_test_ctl_cache);
EXPORT_PER_CPU_SYMBOL_GPL(msr_test_ctl_cache);
+static bool split_lock_detect_enable;
+
/*
* Just in case our CPU detection goes bad, or you have a weird system,
* allow a way to override the automatic disabling of MPX.
@@ -659,9 +662,15 @@ static void init_intel_misc_features(struct cpuinfo_x86 *c)
static void split_lock_update_msr(void)
{
- /* Enable split lock detection */
- msr_set_bit(MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT);
- this_cpu_or(msr_test_ctl_cache, TEST_CTL_SPLIT_LOCK_DETECT);
+ if (split_lock_detect_enable) {
+ /* Enable split lock detection */
+ msr_set_bit(MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT);
+ this_cpu_or(msr_test_ctl_cache, TEST_CTL_SPLIT_LOCK_DETECT);
+ } else {
+ /* Disable split lock detection */
+ msr_clear_bit(MSR_TEST_CTL, TEST_CTL_SPLIT_LOCK_DETECT_SHIFT);
+ this_cpu_and(msr_test_ctl_cache, ~TEST_CTL_SPLIT_LOCK_DETECT);
+ }
}
static void init_split_lock_detect(struct cpuinfo_x86 *c)
@@ -1060,7 +1069,15 @@ cpu_dev_register(intel_cpu_dev);
static void __init set_split_lock_detect(void)
{
setup_force_cpu_cap(X86_FEATURE_SPLIT_LOCK_DETECT);
- pr_info("enabled\n");
+
+ if (cmdline_find_option_bool(boot_command_line,
+ "nosplit_lock_detect")) {
+ split_lock_detect_enable = false;
+ pr_info("disabled\n");
+ } else {
+ split_lock_detect_enable = true;
+ pr_info("enabled\n");
+ }
}
void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c)
--
2.19.1
