Commit 064a59b6 authored by Jacob Pan's avatar Jacob Pan Committed by Ingo Molnar
Browse files

x86/mrst: Avoid reporting wrong nmi status 



Moorestown/Medfield platform does not have port 0x61 to report
NMI status, nor does it have external NMI sources. The only NMI
sources are from lapic, as results of perf counter overflow or
IPI, e.g. NMI watchdog or spin lock debug.

Reading port 0x61 on Moorestown will return 0xff which misled
NMI handlers to false critical errors such memory parity error.
The subsequent ioport access for NMI handling can also cause
undefined behavior on Moorestown.

This patch allows kernel process NMI due to watchdog or backrace
dump without unnecessary hangs.

Signed-off-by: default avatarJacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
[hand applied]
Signed-off-by: default avatarAlan Cox <alan@linux.intel.com>
parent 0a915326

arch/x86/include/asm/mach_traps.h

+1 −1
Original line number Diff line number Diff line
@@ -17,7 +17,7 @@ 
#define NMI_REASON_CLEAR_IOCHK	0x08

#define NMI_REASON_CLEAR_MASK	0x0f



static inline unsigned char get_nmi_reason(void)

static inline unsigned char default_get_nmi_reason(void)

{

	return inb(NMI_REASON_PORT);

}

arch/x86/include/asm/x86_init.h

+1 −0
Original line number Diff line number Diff line
@@ -167,6 +167,7 @@ struct x86_platform_ops { 
	void (*iommu_shutdown)(void);

	bool (*is_untracked_pat_range)(u64 start, u64 end);

	void (*nmi_init)(void);

	unsigned char (*get_nmi_reason)(void);

	int (*i8042_detect)(void);

};

arch/x86/kernel/nmi.c

+1 −1
Original line number Diff line number Diff line
@@ -348,7 +348,7 @@ static notrace __kprobes void default_do_nmi(struct pt_regs *regs) 


	/* Non-CPU-specific NMI: NMI sources can be processed on any CPU */

	raw_spin_lock(&nmi_reason_lock);

	reason = get_nmi_reason();

	reason = x86_platform.get_nmi_reason();



	if (reason & NMI_REASON_MASK) {

		if (reason & NMI_REASON_SERR)

arch/x86/kernel/x86_init.c

+2 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ 
#include <asm/pat.h>

#include <asm/tsc.h>

#include <asm/iommu.h>

#include <asm/mach_traps.h>



void __cpuinit x86_init_noop(void) { }

void __init x86_init_uint_noop(unsigned int unused) { }
@@ -104,6 +105,7 @@ struct x86_platform_ops x86_platform = { 
	.iommu_shutdown			= iommu_shutdown_noop,

	.is_untracked_pat_range		= is_ISA_range,

	.nmi_init			= default_nmi_init,

	.get_nmi_reason			= default_get_nmi_reason,

	.i8042_detect			= default_i8042_detect

};

arch/x86/platform/mrst/mrst.c

+13 −0
Original line number Diff line number Diff line
@@ -276,6 +276,17 @@ static void mrst_reboot(void) 
	intel_scu_ipc_simple_command(0xf1, 0);

}



/*

 * Moorestown does not have external NMI source nor port 0x61 to report

 * NMI status. The possible NMI sources are from pmu as a result of NMI

 * watchdog or lock debug. Reading io port 0x61 results in 0xff which

 * misled NMI handler.

 */

static unsigned char mrst_get_nmi_reason(void)

{

	return 0;

}



/*

 * Moorestown specific x86_init function overrides and early setup

 * calls.
@@ -297,6 +308,8 @@ void __init x86_mrst_early_setup(void) 
	x86_platform.calibrate_tsc = mrst_calibrate_tsc;

	x86_platform.i8042_detect = mrst_i8042_detect;

	x86_init.timers.wallclock_init = mrst_rtc_init;

	x86_platform.get_nmi_reason = mrst_get_nmi_reason;



	x86_init.pci.init = pci_mrst_init;

	x86_init.pci.fixup_irqs = x86_init_noop;

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