Commit b51ef52d authored by Laura Abbott's avatar Laura Abbott Committed by Ingo Molnar
Browse files

x86/cpu: Restore MSR_IA32_ENERGY_PERF_BIAS after resume 



MSR_IA32_ENERGY_PERF_BIAS is lost after suspend/resume:

	x86_energy_perf_policy -r before

	cpu0: 0x0000000000000006
	cpu1: 0x0000000000000006
	cpu2: 0x0000000000000006
	cpu3: 0x0000000000000006
	cpu4: 0x0000000000000006
	cpu5: 0x0000000000000006
	cpu6: 0x0000000000000006
	cpu7: 0x0000000000000006

	after

	cpu0: 0x0000000000000000
	cpu1: 0x0000000000000006
	cpu2: 0x0000000000000006
	cpu3: 0x0000000000000006
	cpu4: 0x0000000000000006
	cpu5: 0x0000000000000006
	cpu6: 0x0000000000000006
	cpu7: 0x0000000000000006

Resulting in inconsistent energy policy settings across CPUs.

This register is set via init_intel() at bootup. During resume,
the secondary CPUs are brought online again and init_intel() is
callled which re-initializes the register. The boot CPU however
never reinitializes the register.

Add a syscore callback to reinitialize the register for the boot CPU.

Signed-off-by: default avatarLaura Abbott <labbott@fedoraproject.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1437428878-4105-1-git-send-email-labbott@fedoraproject.org


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 9d634c41

arch/x86/kernel/cpu/common.c

+18 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
#include <linux/kgdb.h>

#include <linux/smp.h>

#include <linux/io.h>

#include <linux/syscore_ops.h>



#include <asm/stackprotector.h>

#include <asm/perf_event.h>
@@ -1488,3 +1489,20 @@ inline bool __static_cpu_has_safe(u16 bit) 
	return boot_cpu_has(bit);

}

EXPORT_SYMBOL_GPL(__static_cpu_has_safe);



static void bsp_resume(void)

{

	if (this_cpu->c_bsp_resume)

		this_cpu->c_bsp_resume(&boot_cpu_data);

}



static struct syscore_ops cpu_syscore_ops = {

	.resume		= bsp_resume,

};



static int __init init_cpu_syscore(void)

{

	register_syscore_ops(&cpu_syscore_ops);

	return 0;

}

core_initcall(init_cpu_syscore);

arch/x86/kernel/cpu/cpu.h

+1 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ struct cpu_dev { 
	void		(*c_init)(struct cpuinfo_x86 *);

	void		(*c_identify)(struct cpuinfo_x86 *);

	void		(*c_detect_tlb)(struct cpuinfo_x86 *);

	void		(*c_bsp_resume)(struct cpuinfo_x86 *);

	int		c_x86_vendor;

#ifdef CONFIG_X86_32

	/* Optional vendor specific routine to obtain the cache size. */

arch/x86/kernel/cpu/intel.c

+32 −15
Original line number Diff line number Diff line
@@ -371,6 +371,36 @@ static void detect_vmx_virtcap(struct cpuinfo_x86 *c) 
	}

}



static void init_intel_energy_perf(struct cpuinfo_x86 *c)

{

	u64 epb;



	/*

	 * Initialize MSR_IA32_ENERGY_PERF_BIAS if not already initialized.

	 * (x86_energy_perf_policy(8) is available to change it at run-time.)

	 */

	if (!cpu_has(c, X86_FEATURE_EPB))

		return;



	rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);

	if ((epb & 0xF) != ENERGY_PERF_BIAS_PERFORMANCE)

		return;



	pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n");

	pr_warn_once("ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)\n");

	epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;

	wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);

}



static void intel_bsp_resume(struct cpuinfo_x86 *c)

{

	/*

	 * MSR_IA32_ENERGY_PERF_BIAS is lost across suspend/resume,

	 * so reinitialize it properly like during bootup:

	 */

	init_intel_energy_perf(c);

}



static void init_intel(struct cpuinfo_x86 *c)

{

	unsigned int l2 = 0;
@@ -478,21 +508,7 @@ static void init_intel(struct cpuinfo_x86 *c) 
	if (cpu_has(c, X86_FEATURE_VMX))

		detect_vmx_virtcap(c);



	/*

	 * Initialize MSR_IA32_ENERGY_PERF_BIAS if BIOS did not.

	 * x86_energy_perf_policy(8) is available to change it at run-time

	 */

	if (cpu_has(c, X86_FEATURE_EPB)) {

		u64 epb;



		rdmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);

		if ((epb & 0xF) == ENERGY_PERF_BIAS_PERFORMANCE) {

			pr_warn_once("ENERGY_PERF_BIAS: Set to 'normal', was 'performance'\n");

			pr_warn_once("ENERGY_PERF_BIAS: View and update with x86_energy_perf_policy(8)\n");

			epb = (epb & ~0xF) | ENERGY_PERF_BIAS_NORMAL;

			wrmsrl(MSR_IA32_ENERGY_PERF_BIAS, epb);

		}

	}

	init_intel_energy_perf(c);

}



#ifdef CONFIG_X86_32
@@ -747,6 +763,7 @@ static const struct cpu_dev intel_cpu_dev = { 
	.c_detect_tlb	= intel_detect_tlb,

	.c_early_init   = early_init_intel,

	.c_init		= init_intel,

	.c_bsp_resume	= intel_bsp_resume,

	.c_x86_vendor	= X86_VENDOR_INTEL,

};

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