Groups > linux.debian.bugs.dist > #1026718

Bug#971058: [PATCH] ACPI / extlog: Check for RDMSR failure

From	Ben Hutchings <ben@decadent.org.uk>
Newsgroups	linux.debian.bugs.dist, linux.debian.kernel
Subject	Bug#971058: [PATCH] ACPI / extlog: Check for RDMSR failure
Date	2020-09-28 00:00 +0200
Message-ID	<ATMS6-6Nb-11@gated-at.bofh.it> (permalink)
References	<ATsTo-3eW-1@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Cross-posted to 2 groups.

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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: stable@vger.kernel.org
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 drivers/acpi/acpi_extlog.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index f138e12b7b82..72f1fb77abcd 100644
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -222,9 +222,9 @@ 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;
 
 	rc = -EINVAL;

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Bug#971058: [PATCH] ACPI / extlog: Check for RDMSR failure Ben Hutchings <ben@decadent.org.uk> - 2020-09-28 00:00 +0200
  Bug#971058: [PATCH] ACPI / extlog: Check for RDMSR failure "Rafael J. Wysocki" <rafael@kernel.org> - 2020-10-02 19:10 +0200

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