[PATCH v3 10/13] StandaloneMmMmuLib: Allow FF-A calls to get memory region's attributes

["Sughosh Ganu" <sughosh.ganu@linaro.org>]

From: Achin Gupta <achin.gupta@arm.com>

Allow getting memory region's permissions using either of the Firmware
Framework(FF-A) ABI transport or through the earlier used SVC calls.

Signed-off-by: Achin Gupta <achin.gupta@arm.com>
Co-developed-by: Sughosh Ganu <sughosh.ganu@linaro.org>
---

Changes since V2:
* Check for the return value in Arg0 after the Direct Request call to
  handle errors returned
* Put a comment to reflect the fact that FFA_INTERRUPT and FFA_SUCCESS
  response won't be expected in return to a Direct Request call to get
  the memory attributes

 ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf       |  3 +
 ArmPkg/Include/IndustryStandard/ArmFfaSvc.h                       | 18 +++++
 ArmPkg/Library/StandaloneMmMmuLib/AArch64/ArmMmuStandaloneMmLib.c | 78 ++++++++++++++++++--
 3 files changed, 93 insertions(+), 6 deletions(-)

diff --git a/ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf b/ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf
index 85973687f5..a29dd800b5 100644
--- a/ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf
+++ b/ArmPkg/Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf
@@ -23,6 +23,9 @@
   ArmPkg/ArmPkg.dec
   MdePkg/MdePkg.dec
 
+[Pcd]
+  gArmTokenSpaceGuid.PcdFfaEnable
+
 [LibraryClasses]
   ArmLib
   CacheMaintenanceLib
diff --git a/ArmPkg/Include/IndustryStandard/ArmFfaSvc.h b/ArmPkg/Include/IndustryStandard/ArmFfaSvc.h
index bdf6ce4676..65b8343ade 100644
--- a/ArmPkg/Include/IndustryStandard/ArmFfaSvc.h
+++ b/ArmPkg/Include/IndustryStandard/ArmFfaSvc.h
@@ -23,4 +23,22 @@
 #define SPM_MAJOR_VERSION_FFA                           1
 #define SPM_MINOR_VERSION_FFA                           0
 
+#define ARM_FFA_SPM_RET_SUCCESS                          0
+#define ARM_FFA_SPM_RET_NOT_SUPPORTED                   -1
+#define ARM_FFA_SPM_RET_INVALID_PARAMETERS              -2
+#define ARM_FFA_SPM_RET_NO_MEMORY                       -3
+#define ARM_FFA_SPM_RET_BUSY                            -4
+#define ARM_FFA_SPM_RET_INTERRUPTED                     -5
+#define ARM_FFA_SPM_RET_DENIED                          -6
+#define ARM_FFA_SPM_RET_RETRY                           -7
+#define ARM_FFA_SPM_RET_ABORTED                         -8
+
+// For now, the destination id to be used in the FF-A calls
+// is being hard-coded. Subsequently, support will be added
+// to get the endpoint id's dynamically
+// This is the endpoint id used by the optee os's implementation
+// of the spmc.
+// https://github.com/OP-TEE/optee_os/blob/master/core/arch/arm/kernel/stmm_sp.c#L66
+#define ARM_FFA_DESTINATION_ENDPOINT_ID                  3
+
 #endif // ARM_FFA_SVC_H_
diff --git a/ArmPkg/Library/StandaloneMmMmuLib/AArch64/ArmMmuStandaloneMmLib.c b/ArmPkg/Library/StandaloneMmMmuLib/AArch64/ArmMmuStandaloneMmLib.c
index e2770636fb..14fe781630 100644
--- a/ArmPkg/Library/StandaloneMmMmuLib/AArch64/ArmMmuStandaloneMmLib.c
+++ b/ArmPkg/Library/StandaloneMmMmuLib/AArch64/ArmMmuStandaloneMmLib.c
@@ -17,6 +17,7 @@
 #include <Library/BaseLib.h>
 #include <Library/BaseMemoryLib.h>
 #include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
 
 STATIC
 EFI_STATUS
@@ -25,20 +26,85 @@ GetMemoryPermissions (
   OUT UINT32                    *MemoryAttributes
   )
 {
+  INT32         Ret;
   ARM_SVC_ARGS  GetMemoryPermissionsSvcArgs;
+  BOOLEAN       FfaEnabled;
 
   ZeroMem (&GetMemoryPermissionsSvcArgs, sizeof (ARM_SVC_ARGS));
 
-  GetMemoryPermissionsSvcArgs.Arg0 = ARM_SVC_ID_SP_GET_MEM_ATTRIBUTES_AARCH64;
-  GetMemoryPermissionsSvcArgs.Arg1 = BaseAddress;
+  FfaEnabled = FeaturePcdGet (PcdFfaEnable);
+  if (FfaEnabled) {
+    GetMemoryPermissionsSvcArgs.Arg0 = ARM_SVC_ID_FFA_MSG_SEND_DIRECT_REQ_AARCH64;
+    GetMemoryPermissionsSvcArgs.Arg1 = ARM_FFA_DESTINATION_ENDPOINT_ID;
+    GetMemoryPermissionsSvcArgs.Arg2 = 0;
+    GetMemoryPermissionsSvcArgs.Arg3 = ARM_SVC_ID_SP_GET_MEM_ATTRIBUTES_AARCH64;
+    GetMemoryPermissionsSvcArgs.Arg4 = BaseAddress;
+  } else {
+    GetMemoryPermissionsSvcArgs.Arg0 = ARM_SVC_ID_SP_GET_MEM_ATTRIBUTES_AARCH64;
+    GetMemoryPermissionsSvcArgs.Arg1 = BaseAddress;
+    GetMemoryPermissionsSvcArgs.Arg2 = 0;
+    GetMemoryPermissionsSvcArgs.Arg3 = 0;
+  }
 
+  *MemoryAttributes = 0;
   ArmCallSvc (&GetMemoryPermissionsSvcArgs);
-  if (GetMemoryPermissionsSvcArgs.Arg0 == ARM_SVC_SPM_RET_INVALID_PARAMS) {
-    *MemoryAttributes = 0;
-    return EFI_INVALID_PARAMETER;
+  if (FfaEnabled) {
+    // Getting memory attributes is an atomic call, with
+    // StandaloneMm at S-EL0 being the caller and the SPM
+    // core being the callee. Thus there won't be a
+    // FFA_INTERRUPT or FFA_SUCCESS response to the Direct
+    // Request sent above. This will have to be considered
+    // for other Direct Request calls which are not atomic
+    // We therefore check only for Direct Response by the
+    // callee.
+    if (GetMemoryPermissionsSvcArgs.Arg0 !=
+        ARM_SVC_ID_FFA_MSG_SEND_DIRECT_RESP_AARCH64) {
+      // If Arg0 is not a Direct Response, that means we
+      // have an FF-A error. We need to check Arg2 for the
+      // FF-A error code.
+      Ret = GetMemoryPermissionsSvcArgs.Arg2;
+      switch (Ret) {
+      case ARM_FFA_SPM_RET_INVALID_PARAMETERS:
+
+        return EFI_INVALID_PARAMETER;
+
+      case ARM_FFA_SPM_RET_DENIED:
+        return EFI_NOT_READY;
+
+      case ARM_FFA_SPM_RET_NOT_SUPPORTED:
+        return EFI_UNSUPPORTED;
+
+      case ARM_FFA_SPM_RET_BUSY:
+        return EFI_NOT_READY;
+
+      case ARM_FFA_SPM_RET_ABORTED:
+        return EFI_ABORTED;
+      }
+    } else if (GetMemoryPermissionsSvcArgs.Arg0 ==
+               ARM_SVC_ID_FFA_MSG_SEND_DIRECT_RESP_AARCH64) {
+      // A Direct Response means FF-A success
+      // Now check the payload for errors
+      // The callee sends back the return value
+      // in Arg3
+      Ret = GetMemoryPermissionsSvcArgs.Arg3;
+    }
+  } else {
+    Ret = GetMemoryPermissionsSvcArgs.Arg0;
+  }
+
+  if (Ret & BIT31) {
+    // Bit 31 set means there is an error retured
+    switch (Ret) {
+    case ARM_SVC_SPM_RET_INVALID_PARAMS:
+      return EFI_INVALID_PARAMETER;
+
+    case ARM_SVC_SPM_RET_NOT_SUPPORTED:
+      return EFI_UNSUPPORTED;
+    }
+  } else {
+    *MemoryAttributes = Ret;
   }
 
-  *MemoryAttributes = GetMemoryPermissionsSvcArgs.Arg0;
   return EFI_SUCCESS;
 }
 
-- 
2.17.1