From 7cecb47f55e00282f972a1e0b09136c8cd938221 Mon Sep 17 00:00:00 2001
From: Ben Hutchings <ben@decadent.org.uk>
Date: Sun, 27 Sep 2020 22:50:42 +0100
Subject: [PATCH] ACPI / extlog: Check for RDMSR failure
Git-commit: 7cecb47f55e00282f972a1e0b09136c8cd938221
Patch-mainline: v5.10-rc1
References: git-fixes
extlog_init() uses rdmsrl() to read an MSR, which on older CPUs
provokes a error message at boot:
unchecked MSR access error: RDMSR from 0x179 at rIP: 0xcd047307 (native_read_msr+0x7/0x40)
Use rdmsrl_safe() instead, and return -ENODEV if it fails.
Reported-by: jim@photojim.ca
References: https://bugs.debian.org/971058
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/acpi/acpi_extlog.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -224,9 +224,9 @@ static int __init extlog_init(void)
u64 cap;
int rc;
- rdmsrl(MSR_IA32_MCG_CAP, cap);
-
- if (!(cap & MCG_ELOG_P) || !extlog_get_l1addr())
+ if (rdmsrl_safe(MSR_IA32_MCG_CAP, &cap) ||
+ !(cap & MCG_ELOG_P) ||
+ !extlog_get_l1addr())
return -ENODEV;
if (edac_get_report_status() == EDAC_REPORTING_FORCE) {