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Message-Id: <1560897679-228028-14-git-send-email-fenghua.yu@intel.com>
Date: Tue, 18 Jun 2019 15:41:15 -0700
From: Fenghua Yu <fenghua.yu@...el.com>
To: "Thomas Gleixner" <tglx@...utronix.de>,
"Ingo Molnar" <mingo@...hat.com>, "Borislav Petkov" <bp@...en8.de>,
"H Peter Anvin" <hpa@...or.com>,
"Peter Zijlstra" <peterz@...radead.org>,
"Andrew Morton" <akpm@...ux-foundation.org>,
"Dave Hansen" <dave.hansen@...el.com>,
"Paolo Bonzini" <pbonzini@...hat.com>,
"Radim Krcmar" <rkrcmar@...hat.com>,
"Christopherson Sean J" <sean.j.christopherson@...el.com>,
"Ashok Raj" <ashok.raj@...el.com>,
"Tony Luck" <tony.luck@...el.com>,
"Dan Williams" <dan.j.williams@...el.com>,
"Xiaoyao Li " <xiaoyao.li@...el.com>,
"Sai Praneeth Prakhya" <sai.praneeth.prakhya@...el.com>,
"Ravi V Shankar" <ravi.v.shankar@...el.com>
Cc: "linux-kernel" <linux-kernel@...r.kernel.org>,
"x86" <x86@...nel.org>, kvm@...r.kernel.org,
Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH v9 13/17] x86/split_lock: Disable split lock detection by kernel parameter "nosplit_lock_detect"
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@...el.com>
---
.../admin-guide/kernel-parameters.txt | 2 ++
arch/x86/kernel/cpu/intel.c | 22 ++++++++++++++++---
2 files changed, 21 insertions(+), 3 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 138f6664b2e2..bcf578a1bc77 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3086,6 +3086,8 @@
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 4ccd890a45b0..4a854f051cf4 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_cached);
EXPORT_PER_CPU_SYMBOL_GPL(msr_test_ctl_cached);
+static bool split_lock_detect_enabled;
+
/*
* Just in case our CPU detection goes bad, or you have a weird system,
* allow a way to override the automatic disabling of MPX.
@@ -629,8 +632,13 @@ static void init_intel_misc_features(struct cpuinfo_x86 *c)
static void split_lock_update_msr(void)
{
- /* Enable split lock detection */
- this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
+ if (split_lock_detect_enabled) {
+ /* Enable split lock detection */
+ this_cpu_or(msr_test_ctl_cached, MSR_TEST_CTL_SPLIT_LOCK_DETECT);
+ } else {
+ /* Disable split lock detection */
+ this_cpu_and(msr_test_ctl_cached, ~MSR_TEST_CTL_SPLIT_LOCK_DETECT);
+ }
wrmsrl(MSR_TEST_CTL, this_cpu_read(msr_test_ctl_cached));
}
@@ -1027,7 +1035,15 @@ cpu_dev_register(intel_cpu_dev);
static void __init split_lock_setup(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_enabled = false;
+ pr_info("disabled\n");
+ } else {
+ split_lock_detect_enabled = true;
+ pr_info("enabled\n");
+ }
}
void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c)
--
2.19.1
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