• Yong Wang's avatar
    x86: Under BIOS control, restore AP's APIC_LVTTHMR to the BSP value · a2202aa2
    Yong Wang authored
    On platforms where the BIOS handles the thermal monitor interrupt,
    APIC_LVTTHMR on each logical CPU is programmed to generate a SMI
    and OS must not touch it.
    
    Unfortunately AP bringup sequence using INIT-SIPI-SIPI clears all
    the LVT entries except the mask bit. Essentially this results in
    all LVT entries including the thermal monitoring interrupt set
    to masked (clearing the bios programmed value for APIC_LVTTHMR).
    
    And this leads to kernel take over the thermal monitoring
    interrupt on AP's but not on BSP (leaving the bios programmed
    value only on BSP).
    
    As a result of this, we have seen system hangs when the thermal
    monitoring interrupt is generated.
    
    Fix this by reading the initial value of thermal LVT entry on
    BSP and if bios has taken over the control, then program the
    same value on all AP's and leave the thermal monitoring
    interrupt control on all the logical cpu's to the bios.
    Signed-off-by: default avatarYong Wang <yong.y.wang@intel.com>
    Reviewed-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
    Cc: Borislav Petkov <borislav.petkov@amd.com>
    Cc: Arjan van de Ven <arjan@infradead.org>
    LKML-Reference: <20091110013824.GA24940@ywang-moblin2.bj.intel.com>
    Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
    Cc: stable@kernel.org
    a2202aa2
mce.h 6.98 KB