Drivers: hv: vmbus: Implement a clockevent device

Implement a clockevent device based on the timer support available on
Hyper-V.
In this version of the patch I have addressed Jason's review comments.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index 462efe7..90c458e 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -187,6 +187,17 @@
 #define HV_X64_MSR_SINT14			0x4000009E
 #define HV_X64_MSR_SINT15			0x4000009F
 
+/*
+ * Synthetic Timer MSRs. Four timers per vcpu.
+ */
+#define HV_X64_MSR_STIMER0_CONFIG		0x400000B0
+#define HV_X64_MSR_STIMER0_COUNT		0x400000B1
+#define HV_X64_MSR_STIMER1_CONFIG		0x400000B2
+#define HV_X64_MSR_STIMER1_COUNT		0x400000B3
+#define HV_X64_MSR_STIMER2_CONFIG		0x400000B4
+#define HV_X64_MSR_STIMER2_COUNT		0x400000B5
+#define HV_X64_MSR_STIMER3_CONFIG		0x400000B6
+#define HV_X64_MSR_STIMER3_COUNT		0x400000B7
 
 #define HV_X64_MSR_HYPERCALL_ENABLE		0x00000001
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT	12