[PATCH v2 4/5] ArmVirtPkg: Dispatch variable service if variable emulation is enabled

["Sami Mujawar" <sami.mujawar@arm.com>]

The VariableRuntimeDxe links with NvVarStoreFormattedLib which is
required to establish the dependency on OvmfPkg\VirtNorFlashDxe.
The VirtNorFlashDxe installs the gEdkiiNvVarStoreFormattedGuid to
indicate it has finished initialising the flash variable storage
and that the variable service can be dispatched.

However, the kvmtool guest firmware dynamically detects if CFI
flash is absent and sets PcdEmuVariableNvModeEnable to TRUE
indicating emulated runtime variable must be used. Therefore,
in this scenario install the gEdkiiNvVarStoreFormattedGuid so
that the variable service can be dispatched.

Also link the NorFlashKvmtoolLib as a NULL library so that
it can discover if the CFI flash is absent and setup the PCD
PcdEmuVariableNvModeEnable. This is required in case the
NorFlashDxe is not yet dispatched.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---
 ArmVirtPkg/ArmVirtKvmTool.dsc                        |  5 ++++-
 ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c   | 13 ++++++++++++-
 ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf |  4 +++-
 3 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/ArmVirtPkg/ArmVirtKvmTool.dsc b/ArmVirtPkg/ArmVirtKvmTool.dsc
index 25920ab4ae3cce20fdbe8e9ff7e25b8696d2c851..4541d03d23e0d98915b3d3ada688c48d979b75d2 100644
--- a/ArmVirtPkg/ArmVirtKvmTool.dsc
+++ b/ArmVirtPkg/ArmVirtKvmTool.dsc
@@ -311,7 +311,10 @@ [Components.common]
   #
   # Platform Driver
   #
-  ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
+  ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf {
+    <LibraryClasses>
+    NULL|ArmVirtPkg/Library/NorFlashKvmtoolLib/NorFlashKvmtoolLib.inf
+  }
   OvmfPkg/Fdt/VirtioFdtDxe/VirtioFdtDxe.inf
   EmbeddedPkg/Drivers/FdtClientDxe/FdtClientDxe.inf
   OvmfPkg/Fdt/HighMemDxe/HighMemDxe.inf
diff --git a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
index 3f5027fac4d65c4ae3f370c5349c6f410aae5b43..bf6fc1f1f070f32e3ce351f57da955c5cc849409 100644
--- a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
+++ b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.c
@@ -4,7 +4,7 @@
   - It decides if the firmware should expose ACPI or Device Tree-based
     hardware description to the operating system.
 
-  Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.
+  Copyright (c) 2018 - 2023, Arm Limited. All rights reserved.
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -75,6 +75,17 @@ KvmtoolPlatformDxeEntryPoint (
 {
   EFI_STATUS  Status;
 
+  if (PcdGetBool (PcdEmuVariableNvModeEnable)) {
+    // The driver implementing the variable service can now be dispatched.
+    Status = gBS->InstallProtocolInterface (
+                    &gImageHandle,
+                    &gEdkiiNvVarStoreFormattedGuid,
+                    EFI_NATIVE_INTERFACE,
+                    NULL
+                    );
+    ASSERT_EFI_ERROR (Status);
+  }
+
   Status = PlatformHasAcpiDt (ImageHandle);
   ASSERT_EFI_ERROR (Status);
 
diff --git a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
index c5bf798c3b2b7bf1f77e0c5ada9000f536123d6a..b0583d52058805aaeece31d7e3776ac498f101ad 100644
--- a/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
+++ b/ArmVirtPkg/KvmtoolPlatformDxe/KvmtoolPlatformDxe.inf
@@ -3,7 +3,7 @@
 #  - It decides if the firmware should expose ACPI or Device Tree-based
 #    hardware description to the operating system.
 #
-#  Copyright (c) 2018 - 2020, ARM Limited. All rights reserved.
+#  Copyright (c) 2018 - 2023, Arm Limited. All rights reserved.
 #
 #  SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -33,10 +33,12 @@ [LibraryClasses]
   UefiDriverEntryPoint
 
 [Guids]
+  gEdkiiNvVarStoreFormattedGuid   ## SOMETIMES_PRODUCES ## PROTOCOL
   gEdkiiPlatformHasAcpiGuid       ## SOMETIMES_PRODUCES ## PROTOCOL
   gEdkiiPlatformHasDeviceTreeGuid ## SOMETIMES_PRODUCES ## PROTOCOL
 
 [Pcd]
+  gEfiMdeModulePkgTokenSpaceGuid.PcdEmuVariableNvModeEnable
   gUefiOvmfPkgTokenSpaceGuid.PcdForceNoAcpi
 
 [Depex]
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'