lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Tue, 12 Mar 2019 16:00:30 -0700
From:   Fenghua Yu <fenghua.yu@...el.com>
To:     "Thomas Gleixner" <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, "H Peter Anvin" <hpa@...or.com>,
        "Dave Hansen" <dave.hansen@...el.com>,
        "Paolo Bonzini" <pbonzini@...hat.com>,
        "Ashok Raj" <ashok.raj@...el.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        "Xiaoyao Li " <xiaoyao.li@...el.com>,
        "Michael Chan" <michael.chan@...adcom.com>,
        "Ravi V Shankar" <ravi.v.shankar@...el.com>
Cc:     "linux-kernel" <linux-kernel@...r.kernel.org>,
        "x86" <x86@...nel.org>, linux-wireless@...r.kernel.org,
        netdev@...r.kernel.org, kvm@...r.kernel.org,
        Fenghua Yu <fenghua.yu@...el.com>
Subject: [PATCH v5 12/18] x86/split_lock: Enable #AC for split lock by default

Split locked access locks bus and degradates overall memory access
performance. When split lock detection feature is enumerated, we want to
enable the feature by default to find any split lock issue and then fix
the issue.

Signed-off-by: Fenghua Yu <fenghua.yu@...el.com>
---
 arch/x86/kernel/cpu/intel.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index 889390d51c17..561f7d50246a 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -31,6 +31,11 @@
 #include <asm/apic.h>
 #endif
 
+#define DISABLE_SPLIT_LOCK_DETECT 0
+#define ENABLE_SPLIT_LOCK_DETECT  1
+
+static int split_lock_detect_val;
+
 /*
  * Just in case our CPU detection goes bad, or you have a weird system,
  * allow a way to override the automatic disabling of MPX.
@@ -161,10 +166,35 @@ static bool bad_spectre_microcode(struct cpuinfo_x86 *c)
 	return false;
 }
 
+static u32 new_sp_test_ctl_val(u32 test_ctl_val)
+{
+	/* Change the split lock setting. */
+	if (split_lock_detect_val == DISABLE_SPLIT_LOCK_DETECT)
+		test_ctl_val &= ~TEST_CTL_ENABLE_SPLIT_LOCK_DETECT;
+	else
+		test_ctl_val |= TEST_CTL_ENABLE_SPLIT_LOCK_DETECT;
+
+	return test_ctl_val;
+}
+
+static void init_split_lock_detect(struct cpuinfo_x86 *c)
+{
+	if (cpu_has(c, X86_FEATURE_SPLIT_LOCK_DETECT)) {
+		u32 l, h;
+
+		rdmsr(MSR_TEST_CTL, l, h);
+		l = new_sp_test_ctl_val(l);
+		wrmsr(MSR_TEST_CTL, l, h);
+		pr_info_once("#AC for split lock is enabled\n");
+	}
+}
+
 static void early_init_intel(struct cpuinfo_x86 *c)
 {
 	u64 misc_enable;
 
+	init_split_lock_detect(c);
+
 	/* Unmask CPUID levels if masked: */
 	if (c->x86 > 6 || (c->x86 == 6 && c->x86_model >= 0xd)) {
 		if (msr_clear_bit(MSR_IA32_MISC_ENABLE,
@@ -1048,6 +1078,8 @@ void __init cpu_set_core_cap_bits(struct cpuinfo_x86 *c)
 	 */
 	rdmsrl(MSR_IA32_CORE_CAPABILITY, ia32_core_cap);
 
-	if (ia32_core_cap & CORE_CAP_SPLIT_LOCK_DETECT)
+	if (ia32_core_cap & CORE_CAP_SPLIT_LOCK_DETECT) {
 		setup_force_cpu_cap(X86_FEATURE_SPLIT_LOCK_DETECT);
+		split_lock_detect_val = 1;
+	}
 }
-- 
2.19.1

Powered by blists - more mailing lists