ArmVirtPkg/ArmCcaLib: Use GUID HOB to cache IsRealm value

When run early in the QEMU boot, writing the static variable
FlagsInitialised causes a Synchronous Exception. Supposedly the data
page containing the static variable isn't mapped writable at this point,
but I didn't investigate further. Use a GUID HOB to cache the variable.

Signed-off-by: Jean-Philippe Brucker <[email protected]>

Author: jpbrucker

ArmVirtPkg/ArmVirtPkg.dec

@@ -37,6 +37,7 @@
   gEarly16550UartBaseAddressGuid   = { 0xea67ca3e, 0x1f54, 0x436b, { 0x97, 0x88, 0xd4, 0xeb, 0x29, 0xc3, 0x42, 0x67 } }
   gArmVirtSystemMemorySizeGuid     = { 0x504eccb9, 0x1bf0, 0x4420, { 0x86, 0x5d, 0xdc, 0x66, 0x06, 0xd4, 0x13, 0xbf } }
   gArmCcaIpaWidthGuid              = { 0xbdb66787, 0xfc8a, 0x412e, { 0xa0, 0x9b, 0x84, 0x96, 0x61, 0x81, 0x72, 0xc0 } }
+  gArmCcaIsRealmGuid               = { 0x0b3bbff3, 0xed27, 0x4228, { 0xa2, 0x99, 0x8e, 0xd5, 0x14, 0xfb, 0xa2, 0x94 } }
 
 [PcdsFeatureFlag]
   #

ArmVirtPkg/Library/ArmCcaLib/ArmCcaLib.c

@@ -15,6 +15,7 @@
 #include <Library/ArmCcaRsiLib.h>
 #include <Library/ArmMmuLib.h>
 #include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
 
 #include <Uefi/UefiMultiPhase.h>
 #include <Uefi/UefiSpec.h>
@@ -38,11 +39,12 @@ IsRealm (
   UINT32          UefiImpl;
   UINT32          RmmImplLow;
   UINT32          RmmImplHigh;
-  STATIC BOOLEAN  RealmWorld       = FALSE;
-  STATIC BOOLEAN  FlagsInitialised = FALSE;
+  VOID            *Hob;
+  UINT64          *IsRealmHobData;
+  BOOLEAN         RealmWorld       = FALSE;
 
-  if (!FlagsInitialised) {
-    FlagsInitialised = TRUE;
+  Hob = GetFirstGuidHob (&gArmCcaIsRealmGuid);
+  if (Hob == NULL) {
     if (ArmHasRme ()) {
       Status = RsiGetVersion (
                  &UefiImpl,
@@ -53,9 +55,26 @@ IsRealm (
         RealmWorld = TRUE;
       }
     }
+
+    IsRealmHobData = BuildGuidHob (&gArmCcaIsRealmGuid,
+                                   sizeof (*IsRealmHobData));
+    ASSERT (IsRealmHobData != NULL);
+    if (IsRealmHobData == NULL) {
+      return FALSE;
+    }
+    *IsRealmHobData = RealmWorld;
+
+    Hob = GetFirstGuidHob (&gArmCcaIsRealmGuid);
+
+  } else {
+    if (GET_GUID_HOB_DATA_SIZE (Hob) != sizeof (*IsRealmHobData)) {
+      ASSERT (0);
+      return FALSE;
+    }
+    IsRealmHobData = GET_GUID_HOB_DATA (Hob);
   }
 
-  return RealmWorld;
+  return *IsRealmHobData;
 }
 
 /**

ArmVirtPkg/Library/ArmCcaLib/ArmCcaLib.inf

@@ -32,3 +32,4 @@
 
 [Guids]
   gArmCcaIpaWidthGuid
+  gArmCcaIsRealmGuid