[edk2-devel] [RFC PATCH v1 05/30] ArmPkg & ArmVirtPkg: Make PcdMonitorConduitHvc a dynamic PCD

[Sami Mujawar]

The monitor call conduit is fixed for a platform firmware in
most scenarios. For a normal virtual machine guest firmware,
the default conduit is HVC. However, for Arm CCA the Realm
code must use SMC as the conduit.

To have a common code base for Guest/Virtual firmware to be used
by both normal VMs and Realm VMs, make PcdMonitorConduitHvc as a
dynamic PCD. This allows the firmware to detect if it is running
in a Realm and it can configure the PcdMonitorConduitHvc as FALSE
(i.e. to use SMC as the conduit when running in a Realm).

Also update the ArmVirtPkg/ArmVirtKvmTool.dsc workspace to move
the PcdMonitorConduitHvc in the PcdsDynamic section to prevent
the build from breaking.

Signed-off-by: Sami Mujawar <sami.mujawar at arm.com>
---
 ArmPkg/ArmPkg.dec                            | 10 +++++-----
 ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.c |  4 ++--
 ArmVirtPkg/ArmVirtKvmTool.dsc                |  4 ++--
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/ArmPkg/ArmPkg.dec b/ArmPkg/ArmPkg.dec
index f17ba913e6de1326d49b93d6a15378ff2f522d24..0730533e512d60fcba19c4cfa84944061d16f02e 100644
--- a/ArmPkg/ArmPkg.dec
+++ b/ArmPkg/ArmPkg.dec
@@ -139,11 +139,6 @@ [PcdsFeatureFlag.common]
   # Define if the GICv3 controller should use the GICv2 legacy
   gArmTokenSpaceGuid.PcdArmGicV3WithV2Legacy|FALSE|BOOLEAN|0x00000042
 
-  ## Define the conduit to use for monitor calls.
-  # Default PcdMonitorConduitHvc = FALSE, conduit = SMC
-  # If PcdMonitorConduitHvc = TRUE, conduit = HVC
-  gArmTokenSpaceGuid.PcdMonitorConduitHvc|FALSE|BOOLEAN|0x00000047
-
 [PcdsFeatureFlag.ARM]
   # Whether to map normal memory as non-shareable. FALSE is the safe choice, but
   # TRUE may be appropriate to fix performance problems if you don't care about
@@ -393,6 +388,11 @@ [PcdsFixedAtBuild.common, PcdsDynamic.common]
   gArmTokenSpaceGuid.PcdPciBusMin|0x0|UINT32|0x00000059
   gArmTokenSpaceGuid.PcdPciBusMax|0x0|UINT32|0x0000005A
 
+  ## Define the conduit to use for monitor calls.
+  # Default PcdMonitorConduitHvc = FALSE, conduit = SMC
+  # If PcdMonitorConduitHvc = TRUE, conduit = HVC
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|FALSE|BOOLEAN|0x00000047
+
 [PcdsDynamicEx]
   #
   # This dynamic PCD hold the GUID of a firmware FFS which contains
diff --git a/ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.c b/ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.c
index 741f5c615744dc5cc5381ff3848078f93858dd2b..221724125ce3a8f351a55a81f441409a99bcb5cf 100644
--- a/ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.c
+++ b/ArmPkg/Library/ArmMonitorLib/ArmMonitorLib.c
@@ -1,7 +1,7 @@
 /** @file
   Arm Monitor Library.
 
-  Copyright (c) 2022, Arm Limited. All rights reserved.<BR>
+  Copyright (c) 2022 - 2023, Arm Limited. All rights reserved.<BR>
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
 
@@ -26,7 +26,7 @@ ArmMonitorCall (
   IN OUT ARM_MONITOR_ARGS  *Args
   )
 {
-  if (FeaturePcdGet (PcdMonitorConduitHvc)) {
+  if (PcdGetBool (PcdMonitorConduitHvc)) {
     ArmCallHvc ((ARM_HVC_ARGS *)Args);
   } else {
     ArmCallSmc ((ARM_SMC_ARGS *)Args);
diff --git a/ArmVirtPkg/ArmVirtKvmTool.dsc b/ArmVirtPkg/ArmVirtKvmTool.dsc
index d2228a95726b24fe5c2edfbc84b1f5c23a85feba..467e5c166e1bbad3acbae78f53c225f5bac525a9 100644
--- a/ArmVirtPkg/ArmVirtKvmTool.dsc
+++ b/ArmVirtPkg/ArmVirtKvmTool.dsc
@@ -117,8 +117,6 @@ [PcdsFeatureFlag.common]
   # Use MMIO for accessing RTC controller registers.
   gPcAtChipsetPkgTokenSpaceGuid.PcdRtcUseMmio|TRUE
 
-  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
-
 [PcdsFixedAtBuild.common]
   gEfiMdePkgTokenSpaceGuid.PcdDebugPrintErrorLevel|0x8000000F
 
@@ -237,6 +235,8 @@ [PcdsDynamicDefault.common]
   gPcAtChipsetPkgTokenSpaceGuid.PcdRtcIndexRegister64|0x0
   gPcAtChipsetPkgTokenSpaceGuid.PcdRtcTargetRegister64|0x0
 
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'



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