add support for Hyper-V reference time counter

Signed-off: Peter Lieven <pl@kamp.de>
Signed-off: Gleb Natapov
Signed-off: Vadim Rozenfeld <vrozenfe@redhat.com>

After some consideration I decided to submit only Hyper-V reference
counters support this time. I will submit iTSC support as a separate
patch as soon as it is ready.

v1 -> v2
1. mark TSC page dirty as suggested by
    Eric Northup <digitaleric@google.com> and Gleb
2. disable local irq when calling get_kernel_ns,
    as it was done by Peter Lieven <pl@amp.de>
3. move check for TSC page enable from second patch
    to this one.

v3 -> v4
    Get rid of ref counter offset.

v4 -> v5
    replace __copy_to_user with kvm_write_guest
    when updateing iTSC page.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index b8f1c0176cbc..462efe746d77 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -28,6 +28,9 @@
 /* Partition Reference Counter (HV_X64_MSR_TIME_REF_COUNT) available*/
 #define HV_X64_MSR_TIME_REF_COUNT_AVAILABLE     (1 << 1)
 
+/* A partition's reference time stamp counter (TSC) page */
+#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
@@ -198,6 +201,9 @@
 #define HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_MASK        \
                 (~((1ull << HV_X64_MSR_APIC_ASSIST_PAGE_ADDRESS_SHIFT) - 1))
 
+#define HV_X64_MSR_TSC_REFERENCE_ENABLE         0x00000001
+#define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT  12
+
 #define HV_PROCESSOR_POWER_STATE_C0             0
 #define HV_PROCESSOR_POWER_STATE_C1             1
 #define HV_PROCESSOR_POWER_STATE_C2             2
@@ -210,4 +216,11 @@
 #define HV_STATUS_INVALID_ALIGNMENT             4
 #define HV_STATUS_INSUFFICIENT_BUFFERS          19
 
+typedef struct _HV_REFERENCE_TSC_PAGE {
+        __u32 tsc_sequence;
+        __u32 res1;
+        __u64 tsc_scale;
+        __s64 tsc_offset;
+} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
+
 #endif