[PATCH v3] MdeModulePkg/PeiCore: honour minimal runtime allocation granularity

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

Architectures such as AArch64 may run the OS with 16 KB or 64 KB sized
pages, and for this reason, the UEFI spec mandates a minimal allocation
granularity of 64 KB for regions that may require different memory
attributes at OS runtime.

So make PeiCore's implementation of AllocatePages () take this into
account as well.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
v3: allocate a memory allocation HOB to cover the memory lost to rounding

 MdeModulePkg/Core/Pei/Memory/MemoryServices.c | 39 +++++++++++++++++++-
 MdeModulePkg/Core/Pei/PeiMain.h               | 18 +++++++++
 2 files changed, 55 insertions(+), 2 deletions(-)

diff --git a/MdeModulePkg/Core/Pei/Memory/MemoryServices.c b/MdeModulePkg/Core/Pei/Memory/MemoryServices.c
index 4efe14313ca5..573fd606b4cc 100644
--- a/MdeModulePkg/Core/Pei/Memory/MemoryServices.c
+++ b/MdeModulePkg/Core/Pei/Memory/MemoryServices.c
@@ -140,6 +140,8 @@ PeiAllocatePages (
   EFI_PHYSICAL_ADDRESS                    *FreeMemoryTop;
   EFI_PHYSICAL_ADDRESS                    *FreeMemoryBottom;
   UINTN                                   RemainingPages;
+  UINTN                                   Granularity;
+  UINTN                                   Padding;
 
   if ((MemoryType != EfiLoaderCode) &&
       (MemoryType != EfiLoaderData) &&
@@ -153,6 +155,20 @@ PeiAllocatePages (
     return EFI_INVALID_PARAMETER;
   }
 
+  Granularity = DEFAULT_PAGE_ALLOCATION_GRANULARITY;
+
+  if  (RUNTIME_PAGE_ALLOCATION_GRANULARITY > DEFAULT_PAGE_ALLOCATION_GRANULARITY &&
+       (MemoryType == EfiACPIReclaimMemory   ||
+        MemoryType == EfiACPIMemoryNVS       ||
+        MemoryType == EfiRuntimeServicesCode ||
+        MemoryType == EfiRuntimeServicesData)) {
+
+    Granularity = RUNTIME_PAGE_ALLOCATION_GRANULARITY;
+
+    DEBUG ((DEBUG_INFO, "AllocatePages: rounding up allocation to %d KB\n",
+      Granularity));
+  }
+
   PrivateData = PEI_CORE_INSTANCE_FROM_PS_THIS (PeiServices);
   Hob.Raw     = PrivateData->HobList.Raw;
   
@@ -176,9 +192,27 @@ PeiAllocatePages (
   }
 
   //
-  // Check to see if on 4k boundary, If not aligned, make the allocation aligned.
+  // Check to see if on correct boundary for the memory type.
+  // If not aligned, make the allocation aligned.
   //
-  *(FreeMemoryTop) -= *(FreeMemoryTop) & 0xFFF;
+  Padding = *(FreeMemoryTop) & (Granularity - 1);
+  if ((UINTN) (*FreeMemoryTop - *FreeMemoryBottom) < Padding) {
+    DEBUG ((DEBUG_ERROR, "AllocatePages failed: Out of space after padding.\n"));
+    return EFI_OUT_OF_RESOURCES;
+  }
+
+  *(FreeMemoryTop) -= Padding;
+  if (Padding >= EFI_PAGE_SIZE) {
+    //
+    // Create a memory allocation HOB to cover
+    // the pages that we will lose to rounding
+    //
+    BuildMemoryAllocationHob (
+      *(FreeMemoryTop),
+      Padding & ~((UINTN)EFI_PAGE_SIZE - 1),
+      EfiConventionalMemory
+      );
+  }
 
   //
   // Verify that there is sufficient memory to satisfy the allocation.
@@ -192,6 +226,7 @@ PeiAllocatePages (
   //
   // The number of remaining pages needs to be greater than or equal to that of the request pages.
   //
+  Pages = ALIGN_VALUE (Pages, EFI_SIZE_TO_PAGES (Granularity));
   if (RemainingPages < Pages) {
     DEBUG ((EFI_D_ERROR, "AllocatePages failed: No 0x%lx Pages is available.\n", (UINT64) Pages));
     DEBUG ((EFI_D_ERROR, "There is only left 0x%lx pages memory resource to be allocated.\n", (UINT64) RemainingPages));
diff --git a/MdeModulePkg/Core/Pei/PeiMain.h b/MdeModulePkg/Core/Pei/PeiMain.h
index 69eea514920b..e8358d3c4e6d 100644
--- a/MdeModulePkg/Core/Pei/PeiMain.h
+++ b/MdeModulePkg/Core/Pei/PeiMain.h
@@ -55,6 +55,24 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 ///
 #define PEI_CORE_INTERNAL_FFS_FILE_DISPATCH_TYPE   0xff
 
+#if defined (MDE_CPU_AARCH64)
+///
+/// 64-bit ARM systems allow the OS to execute with 64 KB page size,
+/// so for improved interoperability with the firmware, align the
+/// runtime regions to 64 KB as well
+///
+#define RUNTIME_PAGE_ALLOCATION_GRANULARITY       (SIZE_64KB)
+#define DEFAULT_PAGE_ALLOCATION_GRANULARITY       (EFI_PAGE_SIZE)
+
+#else
+///
+/// For generic EFI machines make the default allocations 4K aligned
+///
+#define RUNTIME_PAGE_ALLOCATION_GRANULARITY       (EFI_PAGE_SIZE)
+#define DEFAULT_PAGE_ALLOCATION_GRANULARITY       (EFI_PAGE_SIZE)
+
+#endif
+
 ///
 /// Pei Core private data structures
 ///
-- 
2.7.4