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Commit 2cf02842 authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Thomas Gleixner
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x86/hyperv: Check frequency MSRs presence according to the specification 



Hyper-V TLFS specifies two bits which should be checked before accessing
frequency MSRs:

- AccessFrequencyMsrs (BIT(11) in EAX) which indicates if we have access to
  frequency MSRs.
- FrequencyMsrsAvailable (BIT(8) in EDX) which indicates is these MSRs are
  present.
  
Rename and specify these bits accordingly.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: Stephen Hemminger <sthemmin@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Ladi Prosek <lprosek@redhat.com>
Cc: Jork Loeser <jloeser@microsoft.com>
Cc: devel@linuxdriverproject.org
Cc: "K. Y. Srinivasan" <kys@microsoft.com>
Link: http://lkml.kernel.org/r/20170622100730.18112-2-vkuznets@redhat.com
parent 48b6bbef

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

+2 −1
Original line number Diff line number Diff line
@@ -194,7 +194,8 @@ static void __init ms_hyperv_init_platform(void) 
	}



#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.

		 */