ACPI / extlog: Check for RDMSR failure

commit 7cecb47f55e00282f972a1e0b09136c8cd938221 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/acpi/acpi_extlog.c b/drivers/acpi/acpi_extlog.c
index b3842ffc19ba20a210bec8dd8dc5f56cf9119de9..46d201fc7ecc7133fbedf46e387dde0b805df5bd 100644 (file)
--- a/drivers/acpi/acpi_extlog.c
+++ b/drivers/acpi/acpi_extlog.c
@@ -223,9 +223,9 @@ 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 (get_edac_report_status() == EDAC_REPORTING_FORCE) {