OvmfPkg/PlatformInitLib: check PcdUse1GPageTable

If PcdUse1GPageTable is not enabled restrict the physical address space
used to 1TB, to limit the amount of memory needed for identity mapping
page tables.

The same already happens in case the processor has no support for
gigabyte pages.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>

OvmfPkg/Library/PlatformInitLib/MemDetect.c

@@ -663,6 +663,11 @@ PlatformAddressWidthFromCpuid (
       PhysBits = 40;
     }
 
+    if (!FixedPcdGetBool (PcdUse1GPageTable) && (PhysBits > 40)) {
+      DEBUG ((DEBUG_INFO, "%a: limit PhysBits to 40 (PcdUse1GPageTable is false)\n", __func__));
+      PhysBits = 40;
+    }
+
     PlatformInfoHob->PhysMemAddressWidth = PhysBits;
     PlatformInfoHob->FirstNonAddress     = LShiftU64 (1, PlatformInfoHob->PhysMemAddressWidth);
   }

OvmfPkg/Library/PlatformInitLib/PlatformInitLib.inf

@@ -58,6 +58,7 @@
 
 [Pcd]
   gEfiMdePkgTokenSpaceGuid.PcdPciExpressBaseAddress
+  gEfiMdeModulePkgTokenSpaceGuid.PcdUse1GPageTable
 
 [FixedPcd]
   gUefiOvmfPkgTokenSpaceGuid.PcdOvmfWorkAreaBase