Youquan Song e503f9e4b0 x86, apic: Fix spurious error interrupts triggering on all non-boot APs ... This patch fixes a bug reported by a customer, who found that many unreasonable error interrupts reported on all non-boot CPUs (APs) during the system boot stage. According to Chapter 10 of Intel Software Developer Manual Volume 3A, Local APIC may signal an illegal vector error when an LVT entry is set as an illegal vector value (0~15) under FIXED delivery mode (bits 8-11 is 0), regardless of whether the mask bit is set or an interrupt actually happen. These errors are seen as error interrupts. The initial value of thermal LVT entries on all APs always reads 0x10000 because APs are woken up by BSP issuing INIT-SIPI-SIPI sequence to them and LVT registers are reset to 0s except for the mask bits which are set to 1s when APs receive INIT IPI. When the BIOS takes over the thermal throttling interrupt, the LVT thermal deliver mode should be SMI and it is required from the kernel to keep AP's LVT thermal monitoring register programmed as such as well. This issue happens when BIOS does not take over thermal throttling interrupt, AP's LVT thermal monitor register will be restored to 0x10000 which means vector 0 and fixed deliver mode, so all APs will signal illegal vector error interrupts. This patch check if interrupt delivery mode is not fixed mode before restoring AP's LVT thermal monitor register. Signed-off-by: Youquan Song <youquan.song@intel.com> Acked-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Yong Wang <yong.y.wang@intel.com> Cc: hpa@linux.intel.com Cc: joe@perches.com Cc: jbaron@redhat.com Cc: trenn@suse.de Cc: kent.liu@intel.com Cc: chaohong.guo@intel.com Cc: <stable@kernel.org> # As far back as possible Link: http://lkml.kernel.org/r/1303402963-17738-1-git-send-email-youquan.song@intel.com Signed-off-by: Ingo Molnar <mingo@elte.hu>		2011-05-16 13:48:25 +02:00
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asm	x86, apic: Fix spurious error interrupts triggering on all non-boot APs	2011-05-16 13:48:25 +02:00