Add comments for hb/hypervisor communication struct and remove TODO

Add comments from a previous review and also removed TODOs now
that hdat code is in backing build

Change-Id: Ibf561fdfd7a61b66611a065d77a73fc81dd4e7e7
RTC: 180959
Reviewed-on: http://ralgit01.raleigh.ibm.com/gerrit1/50907
Reviewed-by: Martin Gloff <mgloff@us.ibm.com>
Tested-by: Jenkins Server <pfd-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP Build CI <op-jenkins+hostboot@us.ibm.com>
Reviewed-by: Daniel M. Crowell <dcrowell@us.ibm.com>
Tested-by: FSP CI Jenkins <fsp-CI-jenkins+hostboot@us.ibm.com>
Tested-by: Jenkins OP HW <op-hw-jenkins+hostboot@us.ibm.com>
Reviewed-by: William G. Hoffa <wghoffa@us.ibm.com>

2 files changed, 17 insertions, 7 deletions

diff --git a/src/usr/runtime/hdatstructs.H b/src/usr/runtime/hdatstructs.H
index 41cbd1b19..78c057fde 100644
--- a/src/usr/runtime/hdatstructs.H
+++ b/src/usr/runtime/hdatstructs.H
@@ -394,14 +394,24 @@ const uint64_t HYPECOMM_MAGIC_NUM = 0x48595045434f4d4d;
 // (offset to start of data in hbHypCommArea_t struct)
 const uint8_t  HYPCOMM_STRUCT_HRMOR_OFFSET = 24;
 
+
+//Note when adding data to this make sure to add at the bottom
+//and keep this struct 8 byte aligned
+// We never want to change the format of the first 24 bytes of this struct
 struct hbHypCommArea_t
 {
     uint64_t magicNum;          // 8 bytes 0x48595045434f4d4d = HYPECOMM
     size_t   size;              // 8 bytes
-    uint32_t version;           // 4 bytes
+    uint32_t version;           // 4 bytes keep track of version so we can set the size correctly
     uint8_t padding[4];         // 4 bytes put padding in so hrmor is 8 byte aligned
     //Start Data                // 0x18 or 24 byte offset to data
+    //
+    //The space allocated for HRMOR address can be written to by the hypervisor
+    //in the event that the hypervisor changes its hrmor. This will allow
+    //hostboot to know where to load the payload on MPIPL.
     uint64_t hrmorAddress;      // 8 bytes
+
+    //Total = 32 bytes
     hbHypCommArea_t(): magicNum(HYPECOMM_MAGIC_NUM), size(HB_HYP_COMM_STRUCT_SIZES[STRUCT_VERSION_LATEST]),
                        version(STRUCT_VERSION_LATEST), padding{0,0,0,0}, hrmorAddress(0)
     {
diff --git a/src/usr/runtime/populate_hbruntime.C b/src/usr/runtime/populate_hbruntime.C
index e22e4fa04..f4d69694c 100644
--- a/src/usr/runtime/populate_hbruntime.C
+++ b/src/usr/runtime/populate_hbruntime.C
@@ -533,11 +533,12 @@ errlHndl_t fill_RsvMem_hbData(uint64_t & io_start_address,
                         = sys->getAttr<TARGETING::ATTR_PAYLOAD_KIND>();
 
                     hbHypCommArea_t l_hbCommArea;
+                    static_assert((sizeof(hbHypCommArea_t) % 8) == 0,
+                                  "hbHypCommArea_t's size must be 8 byte aligned");
                     uint64_t l_hdatPtrToHrmorStashAddr = 0;
                     size_t   l_hdatPtrHrmorStashSize   = 0;
-                    //TODO RTC 180959 enable this when HDAT has added in HRMOR ptr space in MS Addr Config section of HDAT
-//                    uint64_t * l_pHdatPtrToHrmorStashAddr;
-//                    memcpy a copy of the hbHypCommArea struct to the end of the hbData section
+                    uint64_t * l_pHdatPtrToHrmorStashAddr;
+                    // memcpy a copy of the hbHypCommArea struct into the reserved mem area
                     memcpy( reinterpret_cast<void*>(l_prevDataAddr),
                             reinterpret_cast<void*>(&l_hbCommArea),
                             sizeof(hbHypCommArea_t));
@@ -564,12 +565,11 @@ errlHndl_t fill_RsvMem_hbData(uint64_t & io_start_address,
                                sizeof(uint64_t), l_hdatPtrHrmorStashSize);
 
                         //Cast the value returned from get_host_data_section to a uint64_t pointer
-    //                     l_pHdatPtrToHrmorStashAddr = reinterpret_cast<uint64_t *>(l_hdatPtrToHrmorStashAddr);
+                        l_pHdatPtrToHrmorStashAddr = reinterpret_cast<uint64_t *>(l_hdatPtrToHrmorStashAddr);
 
-                        //TODO RTC 180959 enable this when HDAT has added in HRMOR ptr space in MS Addr Config section of HDAT
                         //Set the value of the pointer to be the physical address
                         //of the hrmor stash in the hb-hyp communication area
-    //                     *l_pHdatPtrToHrmorStashAddr = io_start_address + l_hbTOC.entry[i].offset + HYPCOMM_STRUCT_HRMOR_OFFSET;
+                        *l_pHdatPtrToHrmorStashAddr = io_start_address + l_hbTOC.entry[i].offset + HYPCOMM_STRUCT_HRMOR_OFFSET;
 
                         TRACFCOMP( g_trac_runtime,
                                   "fill_RsvMem_hbData> HYPCOMM v address 0x%.16llX, size: %lld done",