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    Subject[PATCH 4.19 121/191] ACPI / extlog: Check for RDMSR failure
    Date
    From: Ben Hutchings <ben@decadent.org.uk>

    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
    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>

    ---
    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) {

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