[Xen-devel] [PATCH v3 08/27] ArmVirtualizationPkg: add padding to FDT allocation

[Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>]

Our primary user QEMU/mach-virt presents us with a FDT blob padded
to 64 KB with plenty of room to set additional properties. However,
in the general case, we should only add properties after making sure
there is enough room available.

Contributed-under: TianoCore Contribution Agreement 1.0
Reviewed-by: Laszlo Ersek <lersek@xxxxxxxxxx>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
---
 ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationPkg.dec      | 6 ++++++
 .../ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.c  | 8 +++++---
 .../Library/PlatformPeiLib/PlatformPeiLib.inf                     | 1 +
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationPkg.dec 
b/ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationPkg.dec
index 868488906643..4ebfcddfa595 100644
--- a/ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationPkg.dec
+++ b/ArmPlatformPkg/ArmVirtualizationPkg/ArmVirtualizationPkg.dec
@@ -43,6 +43,12 @@
   #
   
gArmVirtualizationTokenSpaceGuid.PcdDeviceTreeInitialBaseAddress|0x0|UINT64|0x00000001
 
+  #
+  # Padding in bytes to add to the device tree allocation, so that the DTB can
+  # be modified in place (default: 256 bytes)
+  #
+  
gArmVirtualizationTokenSpaceGuid.PcdDeviceTreeAllocationPadding|256|UINT32|0x00000002
+
 [PcdsDynamic, PcdsFixedAtBuild]
   #
   # ARM PSCI function invocations can be done either through hypervisor
diff --git 
a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.c 
b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.c
index c500d5964b25..bdf2b57fcb1e 100644
--- 
a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.c
+++ 
b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.c
@@ -33,6 +33,7 @@ PlatformPeim (
   VOID               *Base;
   VOID               *NewBase;
   UINTN              FdtSize;
+  UINTN              FdtPages;
   UINT64             *FdtHobData;
   UINT64             *UartHobData;
   INT32              Node, Prev;
@@ -47,10 +48,11 @@ PlatformPeim (
   ASSERT (Base != NULL);
   ASSERT (fdt_check_header (Base) == 0);
 
-  FdtSize = fdt_totalsize (Base);
-  NewBase = AllocatePages (EFI_SIZE_TO_PAGES (FdtSize));
+  FdtSize = fdt_totalsize (Base) + PcdGet32 (PcdDeviceTreeAllocationPadding);
+  FdtPages = EFI_SIZE_TO_PAGES (FdtSize);
+  NewBase = AllocatePages (FdtPages);
   ASSERT (NewBase != NULL);
-  CopyMem (NewBase, Base, FdtSize);
+  fdt_open_into (Base, NewBase, EFI_PAGES_TO_SIZE (FdtPages));
 
   FdtHobData = BuildGuidHob (&gFdtHobGuid, sizeof *FdtHobData);
   ASSERT (FdtHobData != NULL);
diff --git 
a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.inf 
b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
index 96019e4009ff..6675a1f91561 100644
--- 
a/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
+++ 
b/ArmPlatformPkg/ArmVirtualizationPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
@@ -40,6 +40,7 @@
   gArmTokenSpaceGuid.PcdFvBaseAddress
   gArmTokenSpaceGuid.PcdFvSize
   gArmVirtualizationTokenSpaceGuid.PcdDeviceTreeInitialBaseAddress
+  gArmVirtualizationTokenSpaceGuid.PcdDeviceTreeAllocationPadding
 
 [Guids]
   gEarlyPL011BaseAddressGuid
-- 
1.8.3.2


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