[RFC PATCH v1 16/30] ArmVirtPkg: Define an interface to configure MMIO regions for Arm CCA

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

The IPA space of a Realm is divided into two halves:
  - Protected IPA space and
  - Unprotected IPA space.

Software in a Realm should treat the most significant bit of an
IPA as a protection attribute.

The Unprotected IPA space is used for sharing memory and for performing
MMIO accesses with the Host.

An Unprotected IPA is an address in the upper half of a Realm's
IPA space. The most significant bit of an Unprotected IPA is 1.

Therefore, the page tables for the MMIO regions must be updated to set
the most significant bit of the IPA space.

To facilitate this define ArmCcaConfigureMmio () that can be called
during the early firmware startup.

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---
 ArmVirtPkg/Include/Library/ArmVirtMemInfoLib.h | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/ArmVirtPkg/Include/Library/ArmVirtMemInfoLib.h b/ArmVirtPkg/Include/Library/ArmVirtMemInfoLib.h
index 7812c2e28657ca9525880dcc0d16d7bca90cc334..b70a96ed923e8c2654e51c9714074744a4d5f0c2 100644
--- a/ArmVirtPkg/Include/Library/ArmVirtMemInfoLib.h
+++ b/ArmVirtPkg/Include/Library/ArmVirtMemInfoLib.h
@@ -1,6 +1,6 @@
 /** @file
 
-  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
+  Copyright (c) 2011-2023, Arm Limited. All rights reserved.
   Copyright (c) 2017, Linaro, Ltd. All rights reserved.
 
   SPDX-License-Identifier: BSD-2-Clause-Patent
@@ -32,4 +32,21 @@ ArmVirtGetMemoryMap (
   OUT ARM_MEMORY_REGION_DESCRIPTOR  **VirtualMemoryMap
   );
 
+/**
+  Configure the MMIO regions as shared with the VMM.
+
+  Set the protection attribute for the MMIO regions as Unprotected IPA.
+
+  @param[in]    IpaWidth  IPA width of the Realm.
+
+  @retval RETURN_SUCCESS            Success.
+  @retval RETURN_INVALID_PARAMETER  A parameter is invalid.
+  @retval RETURN_UNSUPPORTED        The execution context is not in a Realm.
+**/
+EFI_STATUS
+EFIAPI
+ArmCcaConfigureMmio (
+  IN UINT64  IpaWidth
+  );
+
 #endif
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'