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Commit e1449007 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'x86-hyperv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull x86 hyperv updates from Ingo Molnar:
 "Avoid boot time TSC calibration on Hyper-V hosts, to improve
  calibration robustness. (Vitaly Kuznetsov)"

* 'x86-hyperv-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/hyperv: Read TSC frequency from a synthetic MSR
  x86/hyperv: Check frequency MSRs presence according to the specification
parents e6529f6f 71c2a2d0

arch/x86/include/uapi/asm/hyperv.h

+6 −9
Original line number Diff line number Diff line
@@ -34,16 +34,10 @@ 
#define HV_X64_MSR_REFERENCE_TSC		0x40000021



/*

 * There is a single feature flag that signifies the presence of the MSR

 * that can be used to retrieve both the local APIC Timer frequency as

 * well as the TSC frequency.

 * There is a single feature flag that signifies if the partition has access

 * to MSRs with local APIC and TSC frequencies.

 */



/* Local APIC timer frequency MSR (HV_X64_MSR_APIC_FREQUENCY) is available */

#define HV_X64_MSR_APIC_FREQUENCY_AVAILABLE (1 << 11)



/* TSC frequency MSR (HV_X64_MSR_TSC_FREQUENCY) is available */

#define HV_X64_MSR_TSC_FREQUENCY_AVAILABLE (1 << 11)

#define HV_X64_ACCESS_FREQUENCY_MSRS		(1 << 11)



/*

 * Basic SynIC MSRs (HV_X64_MSR_SCONTROL through HV_X64_MSR_EOM
@@ -73,6 +67,9 @@ 
  */

#define HV_X64_MSR_STAT_PAGES_AVAILABLE		(1 << 8)



/* Frequency MSRs available */

#define HV_FEATURE_FREQUENCY_MSRS_AVAILABLE	(1 << 8)



/* Crash MSR available */

#define HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE (1 << 10)

arch/x86/kernel/cpu/mshyperv.c

+17 −1
Original line number Diff line number Diff line
@@ -161,6 +161,15 @@ static int hv_nmi_unknown(unsigned int val, struct pt_regs *regs) 
}

#endif



static unsigned long hv_get_tsc_khz(void)

{

	unsigned long freq;



	rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);



	return freq / 1000;

}



static void __init ms_hyperv_init_platform(void)

{

	int hv_host_info_eax;
@@ -193,8 +202,15 @@ static void __init ms_hyperv_init_platform(void) 
			hv_host_info_edx >> 24, hv_host_info_edx & 0xFFFFFF);

	}



	if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&

	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {

		x86_platform.calibrate_tsc = hv_get_tsc_khz;

		x86_platform.calibrate_cpu = hv_get_tsc_khz;

	}



#ifdef CONFIG_X86_LOCAL_APIC

	if (ms_hyperv.features & HV_X64_MSR_APIC_FREQUENCY_AVAILABLE) {

	if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&

	    ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {

		/*

		 * Get the APIC frequency.

		 */