[PATCH v2 3/4] ArmVirtPkg/NorFlashQemuLib: disregard our primary FV

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

The primary FV contains the firmware boot image, which is not
runtime updatable in our case. So exposing it to the NOR flash
driver is undesirable, since it may attempt to modify the NOR
flash contents. It is also rather pointless, since we don't
keep anything there that we care to expose. (the SEC and PEI
phase modules are not executable from DXE context, and the
contents of the embedded DXE phase FV are exposed by the DXE
core directly via the FVB2 protocol)

So let's disregard the NOR flash block that covers the primary
FV.

Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.inf |  5 +++++
 ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.c   | 13 +++++++++++--
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.inf b/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.inf
index d86ff36dbd58..c5752a243e6b 100644
--- a/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.inf
+++ b/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.inf
@@ -28,6 +28,7 @@ [Sources.common]
 [Packages]
   MdePkg/MdePkg.dec
   ArmPlatformPkg/ArmPlatformPkg.dec
+  ArmPkg/ArmPkg.dec
   ArmVirtPkg/ArmVirtPkg.dec
 
 [LibraryClasses]
@@ -40,3 +41,7 @@ [Protocols]
 
 [Depex]
   gFdtClientProtocolGuid
+
+[Pcd]
+  gArmTokenSpaceGuid.PcdFvBaseAddress
+  gArmTokenSpaceGuid.PcdFvSize
diff --git a/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.c b/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.c
index 2678f57eaaad..d238e39a59f1 100644
--- a/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.c
+++ b/ArmVirtPkg/Library/NorFlashQemuLib/NorFlashQemuLib.c
@@ -75,13 +75,22 @@ NorFlashPlatformGetDevices (
       Size = SwapBytes64 (ReadUnaligned64 ((VOID *)&Reg[2]));
       Reg += 4;
 
+      PropSize -= 4 * sizeof (UINT32);
+
+      //
+      // Disregard any flash devices that overlap with the primary FV.
+      // The firmware is not updatable from inside the guest anyway.
+      //
+      if ((PcdGet64 (PcdFvBaseAddress) + PcdGet32 (PcdFvSize) > Base) &&
+          (Base + Size) > PcdGet64 (PcdFvBaseAddress)) {
+        continue;
+      }
+
       mNorFlashDevices[Num].DeviceBaseAddress = (UINTN)Base;
       mNorFlashDevices[Num].RegionBaseAddress = (UINTN)Base;
       mNorFlashDevices[Num].Size              = (UINTN)Size;
       mNorFlashDevices[Num].BlockSize         = QEMU_NOR_BLOCK_SIZE;
       Num++;
-
-      PropSize -= 4 * sizeof (UINT32);
     }
   }
 
-- 
2.19.1