Arm CCA requires the software in a Realm to treat the most
significant bit of an IPA as a protection attribute. To
enable/disable sharing of memory regions with the host, the
protection attribute needs to be set/cleared accordingly.
Therefore, introduce SetMemoryProtectionAttribute() so that
the memory regions can be shared/unshared with the host.
Cc: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Leif Lindholm <quic_llind...@quicinc.com>
Signed-off-by: Sami Mujawar <sami.muja...@arm.com>
---
ArmPkg/Include/Library/ArmMmuLib.h | 55 ++++++++++++
ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c | 90 ++++++++++++++++++++
2 files changed, 145 insertions(+)
diff --git a/ArmPkg/Include/Library/ArmMmuLib.h
b/ArmPkg/Include/Library/ArmMmuLib.h
index
2ce948e8db1d34e5ba0228de3dc347e186f31c11..1cea71ee6e88d351a3c57c4b97fe229305bfc1af
100644
--- a/ArmPkg/Include/Library/ArmMmuLib.h
+++ b/ArmPkg/Include/Library/ArmMmuLib.h
@@ -71,4 +71,59 @@ ArmSetMemoryAttributes (
IN UINT64 AttributeMask
);
+#ifdef MDE_CPU_AARCH64
+
+/**
+ Configure the protection attribute for the page tables
+ describing the memory region.
+
+ 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.
+
+ A Protected IPA is an address in the lower half of a Realms IPA
+ space. The most significant bit of a Protected IPA is 0.
+
+ An Unprotected IPA is an address in the upper half of a Realms
+ IPA space. The most significant bit of an Unprotected IPA is 1.
+
+ Note:
+ - Configuring the memory region as Unprotected IPA enables the
+ Realm to share the memory region with the Host.
+ - This function updates the page table entries to reflect the
+ protection attribute.
+ - A separate call to transition the memory range using the Realm
+ Service Interface (RSI) RSI_IPA_STATE_SET command is additionally
+ required and is expected to be done outside this function.
+ - The caller must ensure that this function call is invoked by code
+ executing within the Realm.
+
+ @param [in] BaseAddress Base address of the memory region.
+ @param [in] Length Length of the memory region.
+ @param [in] IpaWidth IPA width of the Realm.
+ @param [in] Share If TRUE, set the most significant
+ bit of the IPA to configure the memory
+ region as Unprotected IPA.
+ If FALSE, clear the most significant
+ bit of the IPA to configure the memory
+ region as Protected IPA.
+
+ @retval EFI_SUCCESS IPA protection attribute updated.
+ @retval EFI_INVALID_PARAMETER A parameter is invalid.
+ @retval EFI_UNSUPPORTED RME is not supported.
+**/
+EFI_STATUS
+EFIAPI
+SetMemoryProtectionAttribute (
+ IN EFI_PHYSICAL_ADDRESS BaseAddress,
+ IN UINT64 Length,
+ IN UINT64 IpaWidth,
+ IN BOOLEAN Share
+ );
+
+#endif
+
#endif // ARM_MMU_LIB_H_
diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
index
9d9c623581fe0010e35cb33c0c8ef4061720a6f7..25d32cceb61e1f0fd62d878202cf8ead05cfd9e2
100644
--- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
+++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibCore.c
@@ -7,6 +7,10 @@
*
* SPDX-License-Identifier: BSD-2-Clause-Patent
*
+* @par Glossary:
+* - Rsi or RSI - Realm Service Interface
+* - IPA - Intermediate Physical Address
+* - RIPAS - Realm IPA state
**/
#include <Uefi.h>
@@ -749,3 +753,89 @@ ArmMmuBaseLibConstructor (
return RETURN_SUCCESS;
}
+
+/**
+ Configure the protection attribute for the page tables
+ describing the memory region.
+
+ 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.
+
+ A Protected IPA is an address in the lower half of a Realms IPA
+ space. The most significant bit of a Protected IPA is 0.
+
+ An Unprotected IPA is an address in the upper half of a Realms
+ IPA space. The most significant bit of an Unprotected IPA is 1.
+
+ Note:
+ - Configuring the memory region as Unprotected IPA enables the
+ Realm to share the memory region with the Host.
+ - This function updates the page table entries to reflect the
+ protection attribute.
+ - A separate call to transition the memory range using the Realm
+ Service Interface (RSI) RSI_IPA_STATE_SET command is additionally
+ required and is expected to be done outside this function.
+ - The caller must ensure that this function call is invoked by code
+ executing within the Realm.
+
+ @param [in] BaseAddress Base address of the memory region.
+ @param [in] Length Length of the memory region.
+ @param [in] IpaWidth IPA width of the Realm.
+ @param [in] Share If TRUE, set the most significant
+ bit of the IPA to configure the memory
+ region as Unprotected IPA.
+ If FALSE, clear the most significant
+ bit of the IPA to configure the memory
+ region as Protected IPA.
+
+ @retval EFI_SUCCESS IPA protection attribute updated.
+ @retval EFI_INVALID_PARAMETER A parameter is invalid.
+ @retval EFI_UNSUPPORTED RME is not supported.
+**/
+EFI_STATUS
+EFIAPI
+SetMemoryProtectionAttribute (
+ IN EFI_PHYSICAL_ADDRESS BaseAddress,
+ IN UINT64 Length,
+ IN UINT64 IpaWidth,
+ IN BOOLEAN Share
+ )
+{
+ UINT64 Attributes;
+ UINT64 Mask;
+ UINT64 ProtectionAttributeMask;
+
+ if ((Length == 0) || (IpaWidth == 0)) {
+ return EFI_INVALID_PARAMETER;
+ }
+
+ if (!ArmHasRme ()) {
+ return EFI_UNSUPPORTED;
+ }
+
+ /* Software in a Realm should treat the most significant bit of an
+ IPA as a protection attribute.
+ */
+ ProtectionAttributeMask = 1ULL << (IpaWidth - 1);
+
+ if (Share) {
+ Attributes = ProtectionAttributeMask;
+ Mask = ~TT_ADDRESS_MASK_BLOCK_ENTRY;
+ } else {
+ Attributes = 0;
+ Mask = ~(TT_ADDRESS_MASK_BLOCK_ENTRY | ProtectionAttributeMask);
+ }
+
+ return UpdateRegionMapping (
+ BaseAddress,
+ Length,
+ Attributes,
+ Mask,
+ ArmGetTTBR0BaseAddress (),
+ TRUE
+ );
+}
--
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
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