[RFC PATCH v1 10/30] ArmVirtPkg: ArmCcaRsiLib: Add an interface to make a RSI Host Call

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

The Section A4.5 Host call, RMM Specification, version A-bet0
describes the programming model for Realm communication with
the Host and specifies the following:
  DYDJWT - A Host call is a call made by the Realm to the Host, by
           execution of the RSI_HOST_CALL command.
  IXNFKZ - A Host call can be used by a Realm to make a hypercall.
  DYDJWT - A Host call is a call made by the Realm to the Host, by
           execution of the RSI_HOST_CALL command.

Therefore, introduce definition of HOST_CALL_ARGS structure that
represents the arguments to the RSI_HOST_CALL command as defined
in Section B4.3.3 RSI_HOST_CALL command.

Also update the ArmCcaRsiLib library to add a new interface
RsiHostCall () to make a Host call.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---
 ArmVirtPkg/Include/Library/ArmCcaRsiLib.h      | 36 ++++++++++++++++++
 ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsi.h    |  1 +
 ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsiLib.c | 40 ++++++++++++++++++++
 3 files changed, 77 insertions(+)

diff --git a/ArmVirtPkg/Include/Library/ArmCcaRsiLib.h b/ArmVirtPkg/Include/Library/ArmCcaRsiLib.h
index 51527071ab87aa82efa9ddc3064bb88803d5ba13..5468b2506522bbc9a1467045df0eed6fc70f24de 100644
--- a/ArmVirtPkg/Include/Library/ArmCcaRsiLib.h
+++ b/ArmVirtPkg/Include/Library/ArmCcaRsiLib.h
@@ -81,6 +81,21 @@ typedef struct RealmConfig {
   UINT8     Reserved[SIZE_4KB - sizeof (UINT64)];
 } REALM_CONFIG;
 
+/** A structure describing the Host Call arguments
+    See Section 4.4.2 RsiHostCall type, RMM Specification, version A-bet0
+*/
+typedef struct HostCallArgs {
+  UINT64    Imm;
+  UINT64    Gprs0;
+  UINT64    Gprs1;
+  UINT64    Gprs2;
+  UINT64    Gprs3;
+  UINT64    Gprs4;
+  UINT64    Gprs5;
+  UINT64    Gprs6;
+  UINT8     Reserved[0x1000 - (sizeof (UINT64) * 8)];
+} HOST_CALL_ARGS;
+
 /**
   Retrieve an attestation token from the RMM.
 
@@ -198,6 +213,27 @@ RsiGetRealmConfig (
   IN  REALM_CONFIG  *Config
   );
 
+/**
+  Make a Host Call.
+
+  A Host call can be used by a Realm to make a hypercall.
+  On Realm execution of HVC, an Unknown exception is taken to the Realm.
+
+  @param [in] Args    Pointer to the IPA of the Host call data
+                      structure.
+
+  Note: The IPA of the Host call arguments data structure must be aligned
+         to the Realm granule size.
+
+  @retval RETURN_SUCCESS            Success.
+  @retval RETURN_INVALID_PARAMETER  A parameter is invalid.
+**/
+RETURN_STATUS
+EFIAPI
+RsiHostCall (
+  IN  HOST_CALL_ARGS  *Args
+  );
+
 /**
    Get the version of the RSI implementation.
 
diff --git a/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsi.h b/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsi.h
index 6f0ee3061ade5a4a99b717a52d5a241e0e446270..70e84a20711f04c32a5850230cc907a6d231f50b 100644
--- a/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsi.h
+++ b/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsi.h
@@ -20,6 +20,7 @@
 // FIDs for Realm Service Interface calls.
 #define FID_RSI_ATTESTATION_TOKEN_CONTINUE  0xC4000195
 #define FID_RSI_ATTESTATION_TOKEN_INIT      0xC4000194
+#define FID_RSI_HOST_CALL                   0xC4000199
 #define FID_RSI_IPA_STATE_GET               0xC4000198
 #define FID_RSI_IPA_STATE_SET               0xC4000197
 #define FID_RSI_MEASUREMENT_EXTEND          0xC4000193
diff --git a/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsiLib.c b/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsiLib.c
index fd29fc61caf880bcaf96d982f3a4d973e7ebb70f..5b04c8af890fead113b827030f86af5f07698354 100644
--- a/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsiLib.c
+++ b/ArmVirtPkg/Library/ArmCcaRsiLib/ArmCcaRsiLib.c
@@ -489,6 +489,46 @@ RsiGetRealmConfig (
   return RsiCmdStatusToEfiStatus (SmcCmd.Arg0);
 }
 
+/**
+  Make a Host Call.
+
+  A Host call can be used by a Realm to make a hypercall.
+  On Realm execution of HVC, an Unknown exception is taken to the Realm.
+
+  @param [in] Args    Pointer to the IPA of the Host call data
+                      structure.
+
+  Note: The IPA of the Host call arguments data structure must be aligned
+         to the Realm granule size.
+
+  @retval RETURN_SUCCESS            Success.
+  @retval RETURN_INVALID_PARAMETER  A parameter is invalid.
+**/
+RETURN_STATUS
+EFIAPI
+RsiHostCall (
+  IN  HOST_CALL_ARGS  *Args
+  )
+{
+  ARM_SMC_ARGS  SmcCmd;
+
+  if ((Args == NULL) || (!AddrIsGranuleAligned ((UINT64 *)Args))) {
+    return RETURN_INVALID_PARAMETER;
+  }
+
+  STATIC_ASSERT (sizeof (HOST_CALL_ARGS) == SIZE_4KB);
+
+  // Clear the reserved fields
+  ZeroMem (&Args->Reserved, sizeof (Args->Reserved));
+
+  ZeroMem (&SmcCmd, sizeof (SmcCmd));
+  SmcCmd.Arg0 = FID_RSI_HOST_CALL;
+  SmcCmd.Arg1 = (UINTN)Args;
+
+  ArmCallSmc (&SmcCmd);
+  return RsiCmdStatusToEfiStatus (SmcCmd.Arg0);
+}
+
 /**
    Get the version of the RSI implementation.
 
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'