1 files changed, 43 insertions, 4 deletions

diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
index 0614ff3a7d7e..d8d1fadb398a 100644
--- a/drivers/hv/hyperv_vmbus.h
+++ b/drivers/hv/hyperv_vmbus.h
@@ -410,10 +410,49 @@ enum {
 
 #define HV_PRESENT_BIT                  0x80000000
 
-#define HV_LINUX_GUEST_ID_LO            0x00000000
-#define HV_LINUX_GUEST_ID_HI            2976579765
-#define HV_LINUX_GUEST_ID               (((u64)HV_LINUX_GUEST_ID_HI << 32) | \
-                                           HV_LINUX_GUEST_ID_LO)
+/*
+ * The guest OS needs to register the guest ID with the hypervisor.
+ * The guest ID is a 64 bit entity and the structure of this ID is
+ * specified in the Hyper-V specification:
+ *
+ * http://msdn.microsoft.com/en-us/library/windows/hardware/ff542653%28v=vs.85%29.aspx
+ *
+ * While the current guideline does not specify how Linux guest ID(s)
+ * need to be generated, our plan is to publish the guidelines for
+ * Linux and other guest operating systems that currently are hosted
+ * on Hyper-V. The implementation here conforms to this yet
+ * unpublished guidelines.
+ *
+ *
+ * Bit(s)
+ * 63 - Indicates if the OS is Open Source or not; 1 is Open Source
+ * 62:56 - Os Type; Linux is 0x100
+ * 55:48 - Distro specific identification
+ * 47:16 - Linux kernel version number
+ * 15:0  - Distro specific identification
+ *
+ *
+ */
+
+#define HV_LINUX_VENDOR_ID              0x8100
+
+/*
+ * Generate the guest ID based on the guideline described above.
+ */
+
+static inline  __u64 generate_guest_id(__u8 d_info1, __u32 kernel_version,
+                                        __u16 d_info2)
+{
+        __u64 guest_id = 0;
+
+        guest_id = (((__u64)HV_LINUX_VENDOR_ID) << 48);
+        guest_id |= (((__u64)(d_info1)) << 48);
+        guest_id |= (((__u64)(kernel_version)) << 16);
+        guest_id |= ((__u64)(d_info2));
+
+        return guest_id;
+}
+
 
 #define HV_CPU_POWER_MANAGEMENT         (1 << 0)
 #define HV_RECOMMENDATIONS_MAX          4