tree e84a34b587b07243b3d3557795f8e3fa03302fee
parent b33a6363649f0ff83ec81597ea7fe7e688f973cb
author Yong Wang <yong.y.wang@linux.intel.com> 1257817104 +0800
committer Ingo Molnar <mingo@elte.hu> 1257829075 +0100

x86: Under BIOS control, restore AP's APIC_LVTTHMR to the BSP value

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: Yong Wang <yong.y.wang@intel.com>
Reviewed-by: Suresh 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: Ingo Molnar <mingo@elte.hu>
Cc: stable@kernel.org