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Commit 8d806960 authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

x86/apic: Avoid open coded x2apic detection 



enable_IR_x2apic() grew a open coded x2apic detection. Implement a
proper helper function which shares the code with the already existing
x2apic_enabled().

Made it use rdmsrl_safe as suggested by Boris.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20150115211702.285038186@linutronix.de


Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent e9011760

arch/x86/include/asm/apic.h

+10 −9
Original line number Diff line number Diff line
@@ -108,6 +108,15 @@ extern u64 native_apic_icr_read(void); 


extern int x2apic_mode;



static inline bool apic_is_x2apic_enabled(void)

{

	u64 msr;



	if (rdmsrl_safe(MSR_IA32_APICBASE, &msr))

		return false;

	return msr & X2APIC_ENABLE;

}



#ifdef CONFIG_X86_X2APIC

/*

 * Make previous memory operations globally visible before
@@ -175,15 +184,7 @@ extern void check_x2apic(void); 
extern void enable_x2apic(void);

static inline int x2apic_enabled(void)

{

	u64 msr;



	if (!cpu_has_x2apic)

		return 0;



	rdmsrl(MSR_IA32_APICBASE, msr);

	if (msr & X2APIC_ENABLE)

		return 1;

	return 0;

	return cpu_has_x2apic && apic_is_x2apic_enabled();

}



#define x2apic_supported()	(cpu_has_x2apic)

arch/x86/kernel/apic/apic.c

+1 −4
Original line number Diff line number Diff line
@@ -1625,10 +1625,7 @@ void __init enable_IR_x2apic(void) 
	int ret, ir_stat;



	if (!IS_ENABLED(CONFIG_X86_X2APIC)) {

		u64 msr;



		rdmsrl(MSR_IA32_APICBASE, msr);

		if (msr & X2APIC_ENABLE)

		if (apic_is_x2apic_enabled())

			panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");

	}