linux-kernel - [PATCH 1/2] apic: Fix error interrupt report at all APs

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Date:	Thu,  6 Jan 2011 11:28:51 +0800
From:	Youquan Song <youquan.song@...el.com>
To:	linux-kernel@...r.kernel.org, hpa@...ux.intel.com,
	suresh.b.siddha@...el.com
Cc:	arjan@...ux.intel.com, trenn@...e.de, kent.liu@...el.com,
	chaohong.guo@...el.com,
	Youquan Song <youquan.song@...ux.intel.com>,
	Youquan Song <youquan.song@...el.com>
Subject: [PATCH 1/2] apic: Fix error interrupt report at all APs

Recently, customer report that once machine boot, there are many error interrupt
reported with exact number of all APs. 

The root cause is Local APIC will generate error interrupt when it detect
the illegal vector (one in 0 ~ 15) in an interrupt message received or
interrupt generate from local vector table or self IPI. SDM3A.chapter 10.

The thermal sensor register will be reset to 0x10000, current thermal throttling
driver will first restore AP with the thermal sensor register value of geting
from BSP,but BSP thermal sensor register is also set 0x10000.  value 0x10000
means the interrupt vector is zero. After writing 0x10000 to thermal sensor LVT,
the processor will recieve the error interrupt report if the APIC error
interrupt is also set.

Restore thermal sensor value of BSP is useless because it will soon be set to
correct value included legal vector information.  This patch remove the restore
process. So the agony noise of error interrupt will be dismiss when machine boot   

Signed-off-by: Youquan Song <youquan.song@...el.com>
---
 arch/x86/kernel/cpu/mcheck/therm_throt.c |   11 -----------
 1 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/arch/x86/kernel/cpu/mcheck/therm_throt.c b/arch/x86/kernel/cpu/mcheck/therm_throt.c
index 4b68326..1658483 100644
--- a/arch/x86/kernel/cpu/mcheck/therm_throt.c
+++ b/arch/x86/kernel/cpu/mcheck/therm_throt.c
@@ -405,17 +405,6 @@ void intel_init_thermal(struct cpuinfo_x86 *c)
 	 */
 	rdmsr(MSR_IA32_MISC_ENABLE, l, h);

-	/*
-	 * 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.
-	 * Always restore the value that BIOS has programmed on AP based on
-	 * BSP's info we saved since BIOS is always setting the same value
-	 * for all threads/cores
-	 */
-	apic_write(APIC_LVTTHMR, lvtthmr_init);
-
 	h = lvtthmr_init;

 	if ((l & MSR_IA32_MISC_ENABLE_TM1) && (h & APIC_DM_SMI)) {
-- 
1.6.4.2

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