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authorK. Y. Srinivasan <kys@microsoft.com>2013-09-30 17:28:52 +0200
committerH. Peter Anvin <hpa@linux.intel.com>2013-10-10 11:44:12 -0700
commit9e7827b5ea4ca93b4d864bc07c0fafb838d496b1 (patch)
tree6ceba20f6e2961e29dfdf42b02e1881cd629b94b /arch/x86/include/uapi/asm
parentd0e639c9e06d44e713170031fe05fb60ebe680af (diff)
downloadop-kernel-dev-9e7827b5ea4ca93b4d864bc07c0fafb838d496b1.zip
op-kernel-dev-9e7827b5ea4ca93b4d864bc07c0fafb838d496b1.tar.gz
x86, hyperv: Get the local APIC timer frequency from the hypervisor
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>
Diffstat (limited to 'arch/x86/include/uapi/asm')
-rw-r--r--arch/x86/include/uapi/asm/hyperv.h19
1 files changed, 19 insertions, 0 deletions
diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index b80420b..b8f1c01 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -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
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