[PATCH v2 3/5] MdePkg/DxeServicesLib: introduce AllocatePeiAccessiblePages routine

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

Add a routine to DxeServicesLib that abstracts the allocation of memory
that should be accessible by PEI after a warm reboot. We will use it to
replace open coded implementations that limit the address to < 4 GB,
which may not be possible on non-Intel systems that have no 32-bit
addressable memory at all.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 MdePkg/Include/Library/DxeServicesLib.h          | 23 +++++++-
 MdePkg/Library/DxeServicesLib/DxeServicesLib.c   | 55 ++++++++++++++++++++
 MdePkg/Library/DxeServicesLib/DxeServicesLib.inf |  3 ++
 3 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/MdePkg/Include/Library/DxeServicesLib.h b/MdePkg/Include/Library/DxeServicesLib.h
index 7c1c62236d96..20aee68af558 100644
--- a/MdePkg/Include/Library/DxeServicesLib.h
+++ b/MdePkg/Include/Library/DxeServicesLib.h
@@ -305,5 +305,26 @@ GetFileDevicePathFromAnyFv (
   OUT       EFI_DEVICE_PATH_PROTOCOL  **FvFileDevicePath
   );
 
-#endif
+/**
+  Allocates one or more 4KB pages of a given type from a memory region that is
+  accessible to PEI.
+
+  Allocates the number of 4KB pages of type 'MemoryType' and returns a
+  pointer to the allocated buffer.  The buffer returned is aligned on a 4KB
+  boundary.  If Pages is 0, then NULL is returned.  If there is not enough
+  memory remaining to satisfy the request, then NULL is returned.
 
+  @param[in]  MemoryType            The memory type to allocate
+  @param[in]  Pages                 The number of 4 KB pages to allocate.
+
+  @return A pointer to the allocated buffer or NULL if allocation fails.
+
+**/
+VOID *
+EFIAPI
+AllocatePeiAccessiblePages (
+  IN EFI_MEMORY_TYPE  MemoryType,
+  IN UINTN            Pages
+  );
+
+#endif
diff --git a/MdePkg/Library/DxeServicesLib/DxeServicesLib.c b/MdePkg/Library/DxeServicesLib/DxeServicesLib.c
index 1827c9216fbc..6719aabe5d04 100644
--- a/MdePkg/Library/DxeServicesLib/DxeServicesLib.c
+++ b/MdePkg/Library/DxeServicesLib/DxeServicesLib.c
@@ -16,6 +16,7 @@
 
 #include <PiDxe.h>
 #include <Library/DebugLib.h>
+#include <Library/HobLib.h>
 #include <Library/MemoryAllocationLib.h>
 #include <Library/UefiBootServicesTableLib.h>
 #include <Library/DevicePathLib.h>
@@ -1093,3 +1094,57 @@ Done:
 
   return Status;
 }
+
+/**
+  Allocates one or more 4KB pages of a given type from a memory region that is
+  accessible to PEI.
+
+  Allocates the number of 4KB pages of type 'MemoryType' and returns a
+  pointer to the allocated buffer.  The buffer returned is aligned on a 4KB
+  boundary.  If Pages is 0, then NULL is returned.  If there is not enough
+  memory remaining to satisfy the request, then NULL is returned.
+
+  @param[in]  MemoryType            The memory type to allocate
+  @param[in]  Pages                 The number of 4 KB pages to allocate.
+
+  @return A pointer to the allocated buffer or NULL if allocation fails.
+
+**/
+VOID *
+EFIAPI
+AllocatePeiAccessiblePages (
+  IN EFI_MEMORY_TYPE  MemoryType,
+  IN UINTN            Pages
+  )
+{
+  EFI_STATUS                  Status;
+  EFI_ALLOCATE_TYPE           AllocType;
+  EFI_PHYSICAL_ADDRESS        Memory;
+#ifdef MDE_CPU_X64
+  EFI_HOB_HANDOFF_INFO_TABLE  *PhitHob;
+#endif
+
+  if (Pages == 0) {
+    return NULL;
+  }
+
+  AllocType = AllocateAnyPages;
+#ifdef MDE_CPU_X64
+  //
+  // On X64 systems, a X64 build of DXE may be combined with a 32-bit build of
+  // PEI, and so we need to check the memory limit set by PEI, and allocate
+  // below 4 GB if the limit is set to 4 GB or lower.
+  //
+  PhitHob = (EFI_HOB_HANDOFF_INFO_TABLE *)GetHobList ();
+  if (PhitHob->EfiFreeMemoryTop <= MAX_UINT32) {
+    AllocType = AllocateMaxAddress;
+    Memory = MAX_UINT32;
+  }
+#endif
+
+  Status = gBS->AllocatePages (AllocType, MemoryType, Pages, &Memory);
+  if (EFI_ERROR (Status)) {
+    return NULL;
+  }
+  return (VOID *)(UINTN)Memory;
+}
diff --git a/MdePkg/Library/DxeServicesLib/DxeServicesLib.inf b/MdePkg/Library/DxeServicesLib/DxeServicesLib.inf
index bd2faf2f6f2d..b0306c09872f 100644
--- a/MdePkg/Library/DxeServicesLib/DxeServicesLib.inf
+++ b/MdePkg/Library/DxeServicesLib/DxeServicesLib.inf
@@ -44,6 +44,9 @@ [LibraryClasses]
   UefiLib
   UefiBootServicesTableLib
 
+[LibraryClasses.common.X64]
+  HobLib
+
 [Guids]
   gEfiFileInfoGuid                              ## SOMETIMES_CONSUMES ## UNDEFINED
 
-- 
2.17.0