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x86, hyperv: Get the local APIC timer frequency from the hypervisor

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Hyper-V supports a mechanism for retrieving the local APIC frequency.
Use this and bypass the calibration code in the kernel . This would
allow us to boot the Linux kernel as a "modern VM" on Hyper-V where
many of the legacy devices (such as PIT) are not emulated.

I would like to thank Olaf Hering <olaf@aepfle.de>, Jan Beulich <JBeulich@suse.com> and
H. Peter Anvin <h.peter.anvin@intel.com> for their help in this effort.

In this version of the patch, I have addressed Jan's comments.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Link: http://lkml.kernel.org/r/1380554932-9888-1-git-send-email-olaf@aepfle.de
Tested-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
K. Y. Srinivasan
2013-09-30 17:28:52 +02:00
committed by H. Peter Anvin
parent d0e639c9e0
commit 9e7827b5ea
2 changed files with 43 additions and 0 deletions
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19
arch/x86/include/uapi/asm/hyperv.h
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@@ -27,6 +27,19 @@
#define HV_X64_MSR_VP_RUNTIME_AVAILABLE (1 << 0)
/* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/
#define HV_X64_MSR_TIME_REF_COUNT_AVAILABLE (1 << 1)
/*
* 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.
*/
/* 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)
/*
* Basic SynIC MSRs (HV_X64_MSR_SCONTROL through HV_X64_MSR_EOM
* and HV_X64_MSR_SINT0 through HV_X64_MSR_SINT15) available
@@ -136,6 +149,12 @@
/* MSR used to read the per-partition time reference counter */
#define HV_X64_MSR_TIME_REF_COUNT 0x40000020
/* MSR used to retrieve the TSC frequency */
#define HV_X64_MSR_TSC_FREQUENCY 0x40000022
/* MSR used to retrieve the local APIC timer frequency */
#define HV_X64_MSR_APIC_FREQUENCY 0x40000023
/* Define the virtual APIC registers */
#define HV_X64_MSR_EOI 0x40000070
#define HV_X64_MSR_ICR 0x40000071