ArmVirtPkg: Use dynamic PCD to set the SMCCC conduit

On ARM systems, whether SMC or HVC instructions need to be used to issue monitor calls is typically dependent on the exception level, but there are also cases where EL1 might use SMC instructions, so there is no hard and fast rule. For ArmVirtQemu, this does depend strictly on the exception level, so set the default to HVC (for EL1 execution) and override it to SMC when booted at EL2. Cc: Ard Biesheuvel <ardb+tianocore@kernel.org> Cc: Leif Lindholm <quic_llindhol@quicinc.com> Cc: Sami Mujawar <sami.mujawar@arm.com> Cc: Gerd Hoffmann <kraxel@redhat.com> Committed-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Doug Flick [MSFT] <doug.edk2@gmail.com> Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
chengangc · May 24, 2024 · c98f7f7 · c98f7f7
1 parent 865229b
commit c98f7f7
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diff --git a/ArmVirtPkg/ArmVirtCloudHv.dsc b/ArmVirtPkg/ArmVirtCloudHv.dsc
@@ -201,6 +201,9 @@
 [PcdsDynamicHii]
   gUefiOvmfPkgTokenSpaceGuid.PcdForceNoAcpi|L"ForceNoAcpi"|gOvmfVariableGuid|0x0|FALSE|NV,BS
 
+[PcdsPatchableInModule.common]
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
+
 ################################################################################
 #
 # Components Section - list of all EDK II Modules needed by this Platform

diff --git a/ArmVirtPkg/ArmVirtQemu.dsc b/ArmVirtPkg/ArmVirtQemu.dsc
@@ -293,6 +293,10 @@
   gEfiNetworkPkgTokenSpaceGuid.PcdIPv4PXESupport|0x01
   gEfiNetworkPkgTokenSpaceGuid.PcdIPv6PXESupport|0x01
 
+  # whether to use HVC or SMC to issue monitor calls - this typically depends
+  # on the exception level at which the UEFI system firmware executes
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
+
   #
   # TPM2 support
   #

diff --git a/ArmVirtPkg/ArmVirtQemuKernel.dsc b/ArmVirtPkg/ArmVirtQemuKernel.dsc
@@ -203,6 +203,8 @@
   gArmTokenSpaceGuid.PcdFdBaseAddress|0x0
   gArmTokenSpaceGuid.PcdFvBaseAddress|0x0
 
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
+
 [PcdsDynamicDefault.common]
   gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|3
 

diff --git a/ArmVirtPkg/ArmVirtXen.dsc b/ArmVirtPkg/ArmVirtXen.dsc
@@ -120,6 +120,8 @@
   gArmTokenSpaceGuid.PcdFdBaseAddress|0x0
   gArmTokenSpaceGuid.PcdFvBaseAddress|0x0
 
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc|TRUE
+
 [PcdsDynamicDefault.common]
 
   gArmTokenSpaceGuid.PcdArmArchTimerSecIntrNum|0x0

diff --git a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.c
@@ -18,6 +18,8 @@
 #include <Library/FdtSerialPortAddressLib.h>
 #include <libfdt.h>
 
+#include <Chipset/AArch64.h>
+
 #include <Guid/EarlyPL011BaseAddress.h>
 #include <Guid/FdtHob.h>
 
@@ -224,5 +226,17 @@ PlatformPeim (
 
   BuildFvHob (PcdGet64 (PcdFvBaseAddress), PcdGet32 (PcdFvSize));
 
+ #ifdef MDE_CPU_AARCH64
+  //
+  // Set the SMCCC conduit to SMC if executing at EL2, which is typically the
+  // exception level that services HVCs rather than the one that invokes them.
+  //
+  if (ArmReadCurrentEL () == AARCH64_EL2) {
+    Status = PcdSetBoolS (PcdMonitorConduitHvc, FALSE);
+    ASSERT_EFI_ERROR (Status);
+  }
+
+ #endif
+
   return EFI_SUCCESS;
 }
diff --git a/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf b/ArmVirtPkg/Library/PlatformPeiLib/PlatformPeiLib.inf
@@ -45,6 +45,7 @@
 
 [Pcd]
   gArmTokenSpaceGuid.PcdFvBaseAddress
+  gArmTokenSpaceGuid.PcdMonitorConduitHvc
   gEfiSecurityPkgTokenSpaceGuid.PcdTpmBaseAddress             ## SOMETIMES_PRODUCES
   gUefiOvmfPkgTokenSpaceGuid.PcdDeviceTreeInitialBaseAddress