#define HV_X64_MSR_TSC_REFERENCE_ENABLE                0x00000001
 #define HV_X64_MSR_TSC_REFERENCE_ADDRESS_SHIFT 12
 
-
-/* Define hypervisor message types. */
-enum hv_message_type {
-       HVMSG_NONE                      = 0x00000000,
-
-       /* Memory access messages. */
-       HVMSG_UNMAPPED_GPA              = 0x80000000,
-       HVMSG_GPA_INTERCEPT             = 0x80000001,
-
-       /* Timer notification messages. */
-       HVMSG_TIMER_EXPIRED             = 0x80000010,
-
-       /* Error messages. */
-       HVMSG_INVALID_VP_REGISTER_VALUE = 0x80000020,
-       HVMSG_UNRECOVERABLE_EXCEPTION   = 0x80000021,
-       HVMSG_UNSUPPORTED_FEATURE       = 0x80000022,
-
-       /* Trace buffer complete messages. */
-       HVMSG_EVENTLOG_BUFFERCOMPLETE   = 0x80000040,
-
-       /* Platform-specific processor intercept messages. */
-       HVMSG_X64_IOPORT_INTERCEPT      = 0x80010000,
-       HVMSG_X64_MSR_INTERCEPT         = 0x80010001,
-       HVMSG_X64_CPUID_INTERCEPT       = 0x80010002,
-       HVMSG_X64_EXCEPTION_INTERCEPT   = 0x80010003,
-       HVMSG_X64_APIC_EOI              = 0x80010004,
-       HVMSG_X64_LEGACY_FP_ERROR       = 0x80010005
-};
-
 struct hv_nested_enlightenments_control {
        struct {
                __u32 directhypercall:1;
 
 #define HV_MESSAGE_PAYLOAD_BYTE_COUNT  (240)
 #define HV_MESSAGE_PAYLOAD_QWORD_COUNT (30)
 
+/*
+ * Define hypervisor message types. Some of the message types
+ * are x86/x64 specific, but there's no good way to separate
+ * them out into the arch-specific version of hyperv-tlfs.h
+ * because C doesn't provide a way to extend enum types.
+ * Keeping them all in the arch neutral hyperv-tlfs.h seems
+ * the least messy compromise.
+ */
+enum hv_message_type {
+       HVMSG_NONE                      = 0x00000000,
+
+       /* Memory access messages. */
+       HVMSG_UNMAPPED_GPA              = 0x80000000,
+       HVMSG_GPA_INTERCEPT             = 0x80000001,
+
+       /* Timer notification messages. */
+       HVMSG_TIMER_EXPIRED             = 0x80000010,
+
+       /* Error messages. */
+       HVMSG_INVALID_VP_REGISTER_VALUE = 0x80000020,
+       HVMSG_UNRECOVERABLE_EXCEPTION   = 0x80000021,
+       HVMSG_UNSUPPORTED_FEATURE       = 0x80000022,
+
+       /* Trace buffer complete messages. */
+       HVMSG_EVENTLOG_BUFFERCOMPLETE   = 0x80000040,
+
+       /* Platform-specific processor intercept messages. */
+       HVMSG_X64_IOPORT_INTERCEPT      = 0x80010000,
+       HVMSG_X64_MSR_INTERCEPT         = 0x80010001,
+       HVMSG_X64_CPUID_INTERCEPT       = 0x80010002,
+       HVMSG_X64_EXCEPTION_INTERCEPT   = 0x80010003,
+       HVMSG_X64_APIC_EOI              = 0x80010004,
+       HVMSG_X64_LEGACY_FP_ERROR       = 0x80010005
+};
+
 /* Define synthetic interrupt controller message flags. */
 union hv_message_flags {
        __u8 asu8;