blob: 1720a7d5ca52e717c2694387d8f128b3069474a4 [file] [log] [blame]
From 169862a3c221bcca45631790a52b060e7d5d4229 Mon Sep 17 00:00:00 2001
From: Tony Luck <tony.luck@intel.com>
Date: Tue, 25 Feb 2020 17:17:37 -0800
Subject: [PATCH] x86/mce: Fix logic and comments around MSR_PPIN_CTL
commit 59b5809655bdafb0767d3fd00a3e41711aab07e6 upstream.
There are two implemented bits in the PPIN_CTL MSR:
Bit 0: LockOut (R/WO)
Set 1 to prevent further writes to MSR_PPIN_CTL.
Bit 1: Enable_PPIN (R/W)
If 1, enables MSR_PPIN to be accessible using RDMSR.
If 0, an attempt to read MSR_PPIN will cause #GP.
So there are four defined values:
0: PPIN is disabled, PPIN_CTL may be updated
1: PPIN is disabled. PPIN_CTL is locked against updates
2: PPIN is enabled. PPIN_CTL may be updated
3: PPIN is enabled. PPIN_CTL is locked against updates
Code would only enable the X86_FEATURE_INTEL_PPIN feature for case "2".
When it should have done so for both case "2" and case "3".
Fix the final test to just check for the enable bit. Also fix some of
the other comments in this function.
Fixes: 3f5a7896a509 ("x86/mce: Include the PPIN in MCE records when available")
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200226011737.9958-1-tony.luck@intel.com
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
diff --git a/arch/x86/kernel/cpu/mce/intel.c b/arch/x86/kernel/cpu/mce/intel.c
index e43eb6732630..693c8cfac75d 100644
--- a/arch/x86/kernel/cpu/mce/intel.c
+++ b/arch/x86/kernel/cpu/mce/intel.c
@@ -489,17 +489,18 @@ static void intel_ppin_init(struct cpuinfo_x86 *c)
return;
if ((val & 3UL) == 1UL) {
- /* PPIN available but disabled: */
+ /* PPIN locked in disabled mode */
return;
}
- /* If PPIN is disabled, but not locked, try to enable: */
- if (!(val & 3UL)) {
+ /* If PPIN is disabled, try to enable */
+ if (!(val & 2UL)) {
wrmsrl_safe(MSR_PPIN_CTL, val | 2UL);
rdmsrl_safe(MSR_PPIN_CTL, &val);
}
- if ((val & 3UL) == 2UL)
+ /* Is the enable bit set? */
+ if (val & 2UL)
set_cpu_cap(c, X86_FEATURE_INTEL_PPIN);
}
}
--
2.7.4