diff --git a/meta-arm/meta-arm-bsp/recipes-security/trusted-services/secure-partitions/corstone1000/0028-Revert-Add-uefi-variable-append-write-support.patch b/meta-arm/meta-arm-bsp/recipes-security/trusted-services/secure-partitions/corstone1000/0028-Revert-Add-uefi-variable-append-write-support.patch
new file mode 100644
index 0000000..9bb3f91
--- /dev/null
+++ b/meta-arm/meta-arm-bsp/recipes-security/trusted-services/secure-partitions/corstone1000/0028-Revert-Add-uefi-variable-append-write-support.patch
@@ -0,0 +1,1219 @@
+From da3bd0721f2403562b6ae6d1939f5f331fd141bb Mon Sep 17 00:00:00 2001
+From: Gowtham Suresh Kumar <gowtham.sureshkumar@arm.com>
+Date: Wed, 15 Dec 2021 17:23:25 +0000
+Subject: [PATCH] Revert "Add uefi variable append write support"
+
+This reverts commit e8758d9aff0eddae81a74b0191cd027bcdc92c04.
+
+Upstream-Status: Pending [Not submitted to upstream yet]
+Signed-off-by: Gowtham Suresh Kumar <gowtham.sureshkumar@arm.com>
+
+
+---
+ .../backend/test/variable_index_tests.cpp     |  90 +++---
+ .../backend/test/variable_store_tests.cpp     |  72 +----
+ .../backend/uefi_variable_store.c             | 293 ++++++------------
+ .../smm_variable/backend/variable_index.c     |  95 ++++--
+ .../smm_variable/backend/variable_index.h     |  58 ++--
+ .../backend/variable_index_iterator.c         |   4 +-
+ .../backend/variable_index_iterator.h         |   2 +-
+ .../service/smm_variable_service_tests.cpp    |  48 ---
+ protocols/service/smm_variable/parameters.h   |   3 -
+ 9 files changed, 239 insertions(+), 426 deletions(-)
+
+diff --git a/components/service/smm_variable/backend/test/variable_index_tests.cpp b/components/service/smm_variable/backend/test/variable_index_tests.cpp
+index 8edc0e70..c8bacf97 100644
+--- a/components/service/smm_variable/backend/test/variable_index_tests.cpp
++++ b/components/service/smm_variable/backend/test/variable_index_tests.cpp
+@@ -69,37 +69,34 @@ TEST_GROUP(UefiVariableIndexTests)
+ 
+ 	void create_variables()
+ 	{
+-		struct variable_info *info = NULL;
++		const struct variable_info *info = NULL;
+ 
+-		info = variable_index_add_entry(
++		info = variable_index_add_variable(
+ 			&m_variable_index,
+ 			&guid_1,
+ 			name_1.size() * sizeof(int16_t),
+-			name_1.data());
+-		CHECK_TRUE(info);
+-		variable_index_set_variable(
+-			info,
++			name_1.data(),
+ 			EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+-		info = variable_index_add_entry(
++		CHECK_TRUE(info);
++
++		info = variable_index_add_variable(
+ 			&m_variable_index,
+ 			&guid_2,
+ 			name_2.size() * sizeof(int16_t),
+-			name_2.data());
+-		CHECK_TRUE(info);
+-		variable_index_set_variable(
+-			info,
++			name_2.data(),
+ 			EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+-		info = variable_index_add_entry(
++		CHECK_TRUE(info);
++
++		info = variable_index_add_variable(
+ 			&m_variable_index,
+ 			&guid_1,
+ 			name_3.size() * sizeof(int16_t),
+-			name_3.data());
+-		CHECK_TRUE(info);
+-		variable_index_set_variable(
+-			info,
++			name_3.data(),
+ 			EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_RUNTIME_ACCESS);
++
++		CHECK_TRUE(info);
+ 	}
+ 
+ 	static const size_t MAX_VARIABLES = 10;
+@@ -114,7 +111,7 @@ TEST_GROUP(UefiVariableIndexTests)
+ 
+ TEST(UefiVariableIndexTests, emptyIndexOperations)
+ {
+-	struct variable_info *info = NULL;
++	const struct variable_info *info = NULL;
+ 
+ 	/* Expect not to find a variable */
+ 	info = variable_index_find(
+@@ -133,34 +130,36 @@ TEST(UefiVariableIndexTests, emptyIndexOperations)
+ 	POINTERS_EQUAL(NULL, info);
+ 
+ 	/* Remove should silently return */
+-	variable_index_clear_variable(
++	variable_index_remove_variable(
+ 		&m_variable_index,
+ 		info);
+ }
+ 
+ TEST(UefiVariableIndexTests, addWithOversizedName)
+ {
+-	struct variable_info *info = NULL;
++	const struct variable_info *info = NULL;
+ 	std::vector<int16_t> name;
+ 
+ 	name = to_variable_name(L"a long variable name that exceeds the length limit");
+ 
+-	info = variable_index_add_entry(
++	info = variable_index_add_variable(
+ 		&m_variable_index,
+ 		&guid_1,
+ 		name.size() * sizeof(int16_t),
+-		name.data());
++		name.data(),
++		EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+ 	/* Expect the add to fail because of an oversized name */
+ 	POINTERS_EQUAL(NULL, info);
+ 
+ 	name = to_variable_name(L"a long variable name that fits!");
+ 
+-	info = variable_index_add_entry(
++	info = variable_index_add_variable(
+ 		&m_variable_index,
+ 		&guid_1,
+ 		name.size() * sizeof(int16_t),
+-		name.data());
++		name.data(),
++		EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+ 	/* Expect the add succeed */
+ 	CHECK_TRUE(info);
+@@ -168,17 +167,18 @@ TEST(UefiVariableIndexTests, addWithOversizedName)
+ 
+ TEST(UefiVariableIndexTests, variableIndexFull)
+ {
+-	struct variable_info *info = NULL;
++	const struct variable_info *info = NULL;
+ 	EFI_GUID guid = guid_1;
+ 
+ 	/* Expect to be able to fill the index */
+ 	for (size_t i = 0; i < MAX_VARIABLES; ++i) {
+ 
+-		info = variable_index_add_entry(
++		info = variable_index_add_variable(
+ 			&m_variable_index,
+ 			&guid,
+ 			name_1.size() * sizeof(int16_t),
+-			name_1.data());
++			name_1.data(),
++			EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+ 		CHECK_TRUE(info);
+ 
+@@ -187,11 +187,12 @@ TEST(UefiVariableIndexTests, variableIndexFull)
+ 	}
+ 
+ 	/* Variable index should now be full */
+-	info = variable_index_add_entry(
++	info = variable_index_add_variable(
+ 		&m_variable_index,
+ 		&guid,
+ 		name_1.size() * sizeof(int16_t),
+-		name_1.data());
++		name_1.data(),
++		EFI_VARIABLE_BOOTSERVICE_ACCESS);
+ 
+ 	POINTERS_EQUAL(NULL, info);
+ }
+@@ -322,7 +323,7 @@ TEST(UefiVariableIndexTests, dumpBufferTooSmall)
+ TEST(UefiVariableIndexTests, removeVariable)
+ {
+ 	uint8_t buffer[MAX_VARIABLES * sizeof(struct variable_metadata)];
+-	struct variable_info *info = NULL;
++	const struct variable_info *info = NULL;
+ 
+ 	create_variables();
+ 
+@@ -333,7 +334,7 @@ TEST(UefiVariableIndexTests, removeVariable)
+ 		name_2.size() * sizeof(int16_t),
+ 		name_2.data());
+ 
+-	variable_index_clear_variable(
++	variable_index_remove_variable(
+ 		&m_variable_index,
+ 		info);
+ 
+@@ -351,7 +352,7 @@ TEST(UefiVariableIndexTests, removeVariable)
+ 		name_1.size() * sizeof(int16_t),
+ 		name_1.data());
+ 
+-	variable_index_clear_variable(
++	variable_index_remove_variable(
+ 		&m_variable_index,
+ 		info);
+ 
+@@ -369,7 +370,7 @@ TEST(UefiVariableIndexTests, removeVariable)
+ 		name_3.size() * sizeof(int16_t),
+ 		name_3.data());
+ 
+-	variable_index_clear_variable(
++	variable_index_remove_variable(
+ 		&m_variable_index,
+ 		info);
+ 
+@@ -394,7 +395,7 @@ TEST(UefiVariableIndexTests, removeVariable)
+ 
+ TEST(UefiVariableIndexTests, checkIterator)
+ {
+-	struct variable_info *info = NULL;
++	const struct variable_info *info = NULL;
+ 
+ 	create_variables();
+ 
+@@ -418,7 +419,7 @@ TEST(UefiVariableIndexTests, checkIterator)
+ 	UNSIGNED_LONGS_EQUAL(name_2.size() * sizeof(int16_t), info->metadata.name_size);
+ 	MEMCMP_EQUAL(name_2.data(), info->metadata.name, info->metadata.name_size);
+ 
+-	struct variable_info *info_to_remove = info;
++	const struct variable_info *info_to_remove = info;
+ 
+ 	variable_index_iterator_next(&iter);
+ 	CHECK_FALSE(variable_index_iterator_is_done(&iter));
+@@ -434,8 +435,7 @@ TEST(UefiVariableIndexTests, checkIterator)
+ 	CHECK_TRUE(variable_index_iterator_is_done(&iter));
+ 
+ 	/* Now remove the middle entry */
+-	variable_index_clear_variable(&m_variable_index, info_to_remove);
+-	variable_index_remove_unused_entry(&m_variable_index, info_to_remove);
++	variable_index_remove_variable(&m_variable_index, info_to_remove);
+ 
+ 	/* Iterate again but this time there should only be two entries */
+ 	variable_index_iterator_first(&iter, &m_variable_index);
+@@ -478,7 +478,7 @@ TEST(UefiVariableIndexTests, setCheckConstraintsExistingVar)
+ 	constraints.max_size = 100;
+ 
+ 	/* Set check constraints on one of the variables */
+-	struct variable_info *info = variable_index_find(
++	const struct variable_info *info = variable_index_find(
+ 		&m_variable_index,
+ 		&guid_2,
+ 		name_2.size() * sizeof(int16_t),
+@@ -488,7 +488,7 @@ TEST(UefiVariableIndexTests, setCheckConstraintsExistingVar)
+ 	CHECK_TRUE(info->is_variable_set);
+ 	CHECK_FALSE(info->is_constraints_set);
+ 
+-	variable_index_set_constraints(info, &constraints);
++	variable_index_update_constraints(info, &constraints);
+ 
+ 	CHECK_TRUE(info->is_constraints_set);
+ 	CHECK_TRUE(info->is_variable_set);
+@@ -496,7 +496,7 @@ TEST(UefiVariableIndexTests, setCheckConstraintsExistingVar)
+ 	/* Remove the variable but still expect the variable to be indexed
+ 	 * because of the set constraints.
+ 	 */
+-	variable_index_clear_variable(
++	variable_index_remove_variable(
+ 		&m_variable_index,
+ 		info);
+ 
+@@ -588,7 +588,7 @@ TEST(UefiVariableIndexTests, setCheckConstraintsNonExistingVar)
+ 	constraints.max_size = 100;
+ 
+ 	/* Initially expect no variable_info */
+-	struct variable_info *info = variable_index_find(
++	const struct variable_info *info = variable_index_find(
+ 		&m_variable_index,
+ 		&guid_2,
+ 		name_2.size() * sizeof(int16_t),
+@@ -597,19 +597,19 @@ TEST(UefiVariableIndexTests, setCheckConstraintsNonExistingVar)
+ 	CHECK_FALSE(info);
+ 
+ 	/* Adding the check constraints should result in an entry being added */
+-	info = variable_index_add_entry(
++	info = variable_index_add_constraints(
+ 		&m_variable_index,
+ 		&guid_2,
+ 		name_2.size() * sizeof(int16_t),
+-		name_2.data());
+-	CHECK_TRUE(info);
++		name_2.data(),
++		&constraints);
+ 
+-	variable_index_set_constraints(info, &constraints);
++	CHECK_TRUE(info);
+ 	CHECK_FALSE(info->is_variable_set);
+ 	CHECK_TRUE(info->is_constraints_set);
+ 
+ 	/* Updating the variable should cause the variable to be marked as set */
+-	variable_index_set_variable(info, EFI_VARIABLE_RUNTIME_ACCESS);
++	variable_index_update_variable(info, EFI_VARIABLE_RUNTIME_ACCESS);
+ 
+ 	CHECK_TRUE(info->is_variable_set);
+ 	CHECK_TRUE(info->is_constraints_set);
+diff --git a/components/service/smm_variable/backend/test/variable_store_tests.cpp b/components/service/smm_variable/backend/test/variable_store_tests.cpp
+index e90c1067..235642e6 100644
+--- a/components/service/smm_variable/backend/test/variable_store_tests.cpp
++++ b/components/service/smm_variable/backend/test/variable_store_tests.cpp
+@@ -305,37 +305,6 @@ TEST(UefiVariableStoreTests, setGetRoundtrip)
+ 	/* Expect got variable data to be the same as the set value */
+ 	UNSIGNED_LONGLONGS_EQUAL(input_data.size(), output_data.size());
+ 	LONGS_EQUAL(0, input_data.compare(output_data));
+-
+-	/* Extend the variable using an append write */
+-	std::string input_data2 = " jumps over the lazy dog";
+-
+-	status = set_variable(var_name, input_data2, EFI_VARIABLE_APPEND_WRITE);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	status = get_variable(var_name, output_data);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	std::string expected_output = input_data + input_data2;
+-
+-	/* Expect the append write operation to have extended the variable */
+-	UNSIGNED_LONGLONGS_EQUAL(expected_output.size(), output_data.size());
+-	LONGS_EQUAL(0, expected_output.compare(output_data));
+-
+-	/* Expect query_variable_info to return consistent values */
+-	size_t max_variable_storage_size = 0;
+-	size_t remaining_variable_storage_size = 0;
+-	size_t max_variable_size = 0;
+-
+-	status = query_variable_info(
+-		0,
+-		&max_variable_storage_size,
+-		&remaining_variable_storage_size,
+-		&max_variable_size);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(STORE_CAPACITY, max_variable_storage_size);
+-	UNSIGNED_LONGLONGS_EQUAL(MAX_VARIABLE_SIZE, max_variable_size);
+-	UNSIGNED_LONGLONGS_EQUAL(STORE_CAPACITY - expected_output.size(), remaining_variable_storage_size);
+ }
+ 
+ TEST(UefiVariableStoreTests, persistentSetGet)
+@@ -345,8 +314,7 @@ TEST(UefiVariableStoreTests, persistentSetGet)
+ 	std::string input_data = "quick brown fox";
+ 	std::string output_data;
+ 
+-	status = set_variable(var_name, input_data,
+-		EFI_VARIABLE_NON_VOLATILE);
++	status = set_variable(var_name, input_data, EFI_VARIABLE_NON_VOLATILE);
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+ 
+ 	status = get_variable(var_name, output_data);
+@@ -356,22 +324,6 @@ TEST(UefiVariableStoreTests, persistentSetGet)
+ 	UNSIGNED_LONGLONGS_EQUAL(input_data.size(), output_data.size());
+ 	LONGS_EQUAL(0, input_data.compare(output_data));
+ 
+-	/* Extend the variable using an append write */
+-	std::string input_data2 = " jumps over the lazy dog";
+-
+-	status = set_variable(var_name, input_data2,
+-		EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_APPEND_WRITE);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	status = get_variable(var_name, output_data);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	std::string expected_output = input_data + input_data2;
+-
+-	/* Expect the append write operation to have extended the variable */
+-	UNSIGNED_LONGLONGS_EQUAL(expected_output.size(), output_data.size());
+-	LONGS_EQUAL(0, expected_output.compare(output_data));
+-
+ 	/* Expect the variable to survive a power cycle */
+ 	power_cycle();
+ 
+@@ -380,24 +332,8 @@ TEST(UefiVariableStoreTests, persistentSetGet)
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+ 
+ 	/* Still expect got variable data to be the same as the set value */
+-	UNSIGNED_LONGLONGS_EQUAL(expected_output.size(), output_data.size());
+-	LONGS_EQUAL(0, expected_output.compare(output_data));
+-
+-	/* Expect query_variable_info to return consistent values */
+-	size_t max_variable_storage_size = 0;
+-	size_t remaining_variable_storage_size = 0;
+-	size_t max_variable_size = 0;
+-
+-	status = query_variable_info(
+-		EFI_VARIABLE_NON_VOLATILE,
+-		&max_variable_storage_size,
+-		&remaining_variable_storage_size,
+-		&max_variable_size);
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(STORE_CAPACITY, max_variable_storage_size);
+-	UNSIGNED_LONGLONGS_EQUAL(MAX_VARIABLE_SIZE, max_variable_size);
+-	UNSIGNED_LONGLONGS_EQUAL(STORE_CAPACITY - expected_output.size(), remaining_variable_storage_size);
++	UNSIGNED_LONGLONGS_EQUAL(input_data.size(), output_data.size());
++	LONGS_EQUAL(0, input_data.compare(output_data));
+ }
+ 
+ TEST(UefiVariableStoreTests, removeVolatile)
+@@ -436,7 +372,7 @@ TEST(UefiVariableStoreTests, removePersistent)
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+ 
+ 	/* Remove by setting with zero data length */
+-	status = set_variable(var_name, std::string(), EFI_VARIABLE_NON_VOLATILE);
++	status = set_variable(var_name, std::string(), 0);
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, status);
+ 
+ 	/* Expect variable to no loger exist */
+diff --git a/components/service/smm_variable/backend/uefi_variable_store.c b/components/service/smm_variable/backend/uefi_variable_store.c
+index b7cfff40..6a90f46a 100644
+--- a/components/service/smm_variable/backend/uefi_variable_store.c
++++ b/components/service/smm_variable/backend/uefi_variable_store.c
+@@ -47,20 +47,6 @@ static efi_status_t load_variable_data(
+ 	SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE *var,
+ 	size_t max_data_len);
+ 
+-static psa_status_t store_overwrite(
+-	struct delegate_variable_store *delegate_store,
+-	uint32_t client_id,
+-	uint64_t uid,
+-	size_t data_length,
+-	const void *data);
+-
+-static psa_status_t store_append_write(
+-	struct delegate_variable_store *delegate_store,
+-	uint32_t client_id,
+-	uint64_t uid,
+-	size_t data_length,
+-	const void *data);
+-
+ static void purge_orphan_index_entries(
+ 	struct uefi_variable_store *context);
+ 
+@@ -168,45 +154,40 @@ efi_status_t uefi_variable_store_set_variable(
+ 	struct uefi_variable_store *context,
+ 	const SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE *var)
+ {
+-	bool should_sync_index = false;
+-
+-	/* Validate incoming request */
+ 	efi_status_t status = check_name_terminator(var->Name, var->NameSize);
+ 	if (status != EFI_SUCCESS) return status;
+ 
+ 	status = check_capabilities(var);
++	bool should_sync_index = false;
++
+ 	if (status != EFI_SUCCESS) return status;
+ 
+-	/* Find an existing entry in the variable index or add a new one */
+-	struct variable_info *info = variable_index_find(
++	/* Find in index */
++	const struct variable_info *info = variable_index_find(
+ 		&context->variable_index,
+ 		&var->Guid,
+ 		var->NameSize,
+ 		var->Name);
+ 
+-	if (!info) {
++	if (info) {
+ 
+-		info = variable_index_add_entry(
+-			&context->variable_index,
+-			&var->Guid,
+-			var->NameSize,
+-			var->Name);
++		/* Variable info already exists */
++		status = check_access_permitted_on_set(context, info, var);
+ 
+-		if (!info) return EFI_OUT_OF_RESOURCES;
+-	}
++		if (status == EFI_SUCCESS) {
+ 
+-	/* Control access */
+-	status = check_access_permitted_on_set(context, info, var);
++			should_sync_index =
++				(var->Attributes & EFI_VARIABLE_NON_VOLATILE) ||
++				(info->is_variable_set && (info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE));
+ 
+-	if (status == EFI_SUCCESS) {
++			if (var->DataSize) {
+ 
+-		/* Access permitted */
+-		if (info->is_variable_set) {
+-
+-			/* It's a request to update to an existing variable */
+-			if (!(var->Attributes &
+-				(EFI_VARIABLE_APPEND_WRITE | EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS_MASK)) &&
+-				!var->DataSize) {
++				/* It's a set rather than a remove operation */
++				variable_index_update_variable(
++					info,
++					var->Attributes);
++			}
++			else {
+ 
+ 				/* It's a remove operation - for a remove, the variable
+ 				 * data must be removed from the storage backend before
+@@ -215,30 +196,31 @@ efi_status_t uefi_variable_store_set_variable(
+ 				 * the storage backend without a corresponding index entry.
+ 				 */
+ 				remove_variable_data(context, info);
+-				variable_index_clear_variable(&context->variable_index, info);
++				variable_index_remove_variable(&context->variable_index, info);
+ 
+-				should_sync_index = (var->Attributes & EFI_VARIABLE_NON_VOLATILE);
+-			}
+-			else {
+-
+-				/* It's a set operation where variable data is potentially
+-				 * being overwritten or extended.
+-				 */
+-				if ((var->Attributes & ~EFI_VARIABLE_APPEND_WRITE) != info->metadata.attributes) {
+-
+-					/* Modifying attributes is forbidden */
+-					return EFI_INVALID_PARAMETER;
+-				}
++				/* Variable info no longer valid */
++				info = NULL;
+ 			}
+ 		}
+ 		else {
+ 
+-			/*  It's a request to create a new variable */
+-			variable_index_set_variable(info, var->Attributes);
+-
+-			should_sync_index = (var->Attributes & EFI_VARIABLE_NON_VOLATILE);
++			/* Access forbidden */
++			info = NULL;
+ 		}
+ 	}
++	else if (var->DataSize) {
++
++		/* It's a new variable */
++		info = variable_index_add_variable(
++			&context->variable_index,
++			&var->Guid,
++			var->NameSize,
++			var->Name,
++			var->Attributes);
++
++		if (!info) status = EFI_OUT_OF_RESOURCES;
++		should_sync_index = info && (info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE);
++	}
+ 
+ 	/* The order of these operations is important. For an update
+ 	 * or create operation, The variable index is always synchronized
+@@ -254,13 +236,11 @@ efi_status_t uefi_variable_store_set_variable(
+ 	}
+ 
+ 	/* Store any variable data to the storage backend */
+-	if (info->is_variable_set && (status == EFI_SUCCESS)) {
++	if (info && (status == EFI_SUCCESS)) {
+ 
+ 		status = store_variable_data(context, info, var);
+ 	}
+ 
+-	variable_index_remove_unused_entry(&context->variable_index, info);
+-
+ 	return status;
+ }
+ 
+@@ -373,41 +353,53 @@ efi_status_t uefi_variable_store_set_var_check_property(
+ 	efi_status_t status = check_name_terminator(property->Name, property->NameSize);
+ 	if (status != EFI_SUCCESS) return status;
+ 
+-	/* Find in index or create a new entry */
+-	struct variable_info *info = variable_index_find(
++	/* Find in index */
++	const struct variable_info *info = variable_index_find(
+ 		&context->variable_index,
+ 		&property->Guid,
+ 		property->NameSize,
+ 		property->Name);
+ 
+-	if (!info) {
++	if (info) {
+ 
+-		info = variable_index_add_entry(
+-			&context->variable_index,
+-			&property->Guid,
+-			property->NameSize,
+-			property->Name);
++		/* Applying check constraints to an existing variable that may have
++		 * constraints already set.  These could constrain the setting of
++		 * the constraints.
++		 */
++		struct variable_constraints constraints = info->check_constraints;
++
++		status = variable_checker_set_constraints(
++			&constraints,
++			info->is_constraints_set,
++			&property->VariableProperty);
++
++		if (status == EFI_SUCCESS) {
+ 
+-		if (!info) return EFI_OUT_OF_RESOURCES;
++			variable_index_update_constraints(info, &constraints);
++		}
+ 	}
++	else {
+ 
+-	/* Applying check constraints to an existing variable that may have
+-	 * constraints already set.  These could constrain the setting of
+-	 * the constraints.
+-	 */
+-	struct variable_constraints constraints = info->check_constraints;
++		/* Applying check constraints for a new variable */
++		struct variable_constraints constraints;
+ 
+-	status = variable_checker_set_constraints(
+-		&constraints,
+-		info->is_constraints_set,
+-		&property->VariableProperty);
++		status = variable_checker_set_constraints(
++			&constraints,
++			false,
++			&property->VariableProperty);
+ 
+-	if (status == EFI_SUCCESS) {
++		if (status == EFI_SUCCESS) {
+ 
+-		variable_index_set_constraints(info, &constraints);
+-	}
++			info = variable_index_add_constraints(
++				&context->variable_index,
++				&property->Guid,
++				property->NameSize,
++				property->Name,
++				&constraints);
+ 
+-	variable_index_remove_unused_entry(&context->variable_index, info);
++			if (!info) status = EFI_OUT_OF_RESOURCES;
++		}
++	}
+ 
+ 	return status;
+ }
+@@ -514,8 +506,7 @@ static efi_status_t check_capabilities(
+ 	if (var->Attributes & ~(
+ 		EFI_VARIABLE_NON_VOLATILE |
+ 		EFI_VARIABLE_BOOTSERVICE_ACCESS |
+-		EFI_VARIABLE_RUNTIME_ACCESS |
+-		EFI_VARIABLE_APPEND_WRITE)) {
++		EFI_VARIABLE_RUNTIME_ACCESS)) {
+ 
+ 		/* An unsupported attribute has been requested */
+ 		status = EFI_UNSUPPORTED;
+@@ -561,6 +552,17 @@ static efi_status_t check_access_permitted_on_set(
+ 			var->DataSize);
+ 	}
+ 
++	if ((status == EFI_SUCCESS) && var->DataSize) {
++
++		/* Restrict which attributes can be modified for an existing variable */
++		if ((var->Attributes & EFI_VARIABLE_NON_VOLATILE) !=
++			(info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE)) {
++
++			/* Don't permit change of storage class */
++			status = EFI_INVALID_PARAMETER;
++		}
++	}
++
+ 	return status;
+ }
+ 
+@@ -581,33 +583,20 @@ static efi_status_t store_variable_data(
+ 
+ 	if (delegate_store->storage_backend) {
+ 
+-		if (!(var->Attributes & EFI_VARIABLE_APPEND_WRITE)) {
+-
+-			/* Create or overwrite variable data */
+-			psa_status = store_overwrite(
+-				delegate_store,
+-				context->owner_id,
+-				info->metadata.uid,
+-				data_len,
+-				data);
+-		}
+-		else {
+-
+-			/* Append new data to existing variable data */
+-			psa_status = store_append_write(
+-				delegate_store,
+-				context->owner_id,
+-				info->metadata.uid,
+-				data_len,
+-				data);
+-		}
++		psa_status = delegate_store->storage_backend->interface->set(
++			delegate_store->storage_backend->context,
++			context->owner_id,
++			info->metadata.uid,
++			data_len,
++			data,
++			PSA_STORAGE_FLAG_NONE);
+ 	}
+ 
+ 	if ((psa_status != PSA_SUCCESS) && delegate_store->is_nv) {
+ 
+ 		/* A storage failure has occurred so attempt to fix any
+-		 * mismatch between the variable index and stored NV variables.
+-		 */
++		* mismatch between the variable index and stored NV variables.
++		*/
+ 		purge_orphan_index_entries(context);
+ 	}
+ 
+@@ -674,100 +663,6 @@ static efi_status_t load_variable_data(
+ 	return psa_to_efi_storage_status(psa_status);
+ }
+ 
+-static psa_status_t store_overwrite(
+-	struct delegate_variable_store *delegate_store,
+-	uint32_t client_id,
+-	uint64_t uid,
+-	size_t data_length,
+-	const void *data)
+-{
+-	/* Police maximum variable size limit */
+-	if (data_length > delegate_store->max_variable_size) return PSA_ERROR_INVALID_ARGUMENT;
+-
+-	psa_status_t psa_status = delegate_store->storage_backend->interface->set(
+-		delegate_store->storage_backend->context,
+-		client_id,
+-		uid,
+-		data_length,
+-		data,
+-		PSA_STORAGE_FLAG_NONE);
+-
+-	return psa_status;
+-}
+-
+-static psa_status_t store_append_write(
+-	struct delegate_variable_store *delegate_store,
+-	uint32_t client_id,
+-	uint64_t uid,
+-	size_t data_length,
+-	const void *data)
+-{
+-	struct psa_storage_info_t storage_info;
+-
+-	if (data_length == 0) return PSA_SUCCESS;
+-
+-	psa_status_t psa_status = delegate_store->storage_backend->interface->get_info(
+-		delegate_store->storage_backend->context,
+-		client_id,
+-		uid,
+-		&storage_info);
+-
+-	if (psa_status != PSA_SUCCESS) return psa_status;
+-
+-	/* Determine size of appended variable */
+-	size_t new_size = storage_info.size + data_length;
+-
+-	/* Defend against integer overflow */
+-	if (new_size < storage_info.size) return PSA_ERROR_INVALID_ARGUMENT;
+-
+-		/* Police maximum variable size limit */
+-	if (new_size > delegate_store->max_variable_size) return PSA_ERROR_INVALID_ARGUMENT;
+-
+-	/* Storage backend doesn't support an append operation so we need
+-	 * need to read the current variable data, extend it and write it back.
+-	 */
+-	uint8_t *rw_buf = malloc(new_size);
+-	if (!rw_buf) return PSA_ERROR_INSUFFICIENT_MEMORY;
+-
+-	size_t old_size = 0;
+-	psa_status = delegate_store->storage_backend->interface->get(
+-		delegate_store->storage_backend->context,
+-		client_id,
+-		uid,
+-		0,
+-		new_size,
+-		rw_buf,
+-		&old_size);
+-
+-	if (psa_status == PSA_SUCCESS) {
+-
+-		if ((old_size + data_length) <= new_size) {
+-
+-			/* Extend the variable data */
+-			memcpy(&rw_buf[old_size], data, data_length);
+-
+-			psa_status = delegate_store->storage_backend->interface->set(
+-				delegate_store->storage_backend->context,
+-				client_id,
+-				uid,
+-				old_size + data_length,
+-				rw_buf,
+-				storage_info.flags);
+-		}
+-		else {
+-
+-			/* There's a mismatch between the length obtained from
+-			 * get_info() and the subsequent length returned by get().
+-			 */
+-			psa_status = PSA_ERROR_STORAGE_FAILURE;
+-		}
+-	}
+-
+-	free(rw_buf);
+-
+-	return psa_status;
+-}
+-
+ static void purge_orphan_index_entries(
+ 	struct uefi_variable_store *context)
+ {
+@@ -782,7 +677,7 @@ static void purge_orphan_index_entries(
+ 	 */
+ 	while (!variable_index_iterator_is_done(&iter)) {
+ 
+-		struct variable_info *info = variable_index_iterator_current(&iter);
++		const struct variable_info *info = variable_index_iterator_current(&iter);
+ 
+ 		if (info->is_variable_set && (info->metadata.attributes & EFI_VARIABLE_NON_VOLATILE)) {
+ 
+@@ -799,7 +694,7 @@ static void purge_orphan_index_entries(
+ 			if (psa_status != PSA_SUCCESS) {
+ 
+ 				/* Detected a mismatch between the index and storage */
+-				variable_index_clear_variable(&context->variable_index, info);
++				variable_index_remove_variable(&context->variable_index, info);
+ 				any_orphans = true;
+ 			}
+ 		}
+diff --git a/components/service/smm_variable/backend/variable_index.c b/components/service/smm_variable/backend/variable_index.c
+index a8a55753..99d7c97a 100644
+--- a/components/service/smm_variable/backend/variable_index.c
++++ b/components/service/smm_variable/backend/variable_index.c
+@@ -132,13 +132,13 @@ size_t variable_index_max_dump_size(
+ 	return sizeof(struct variable_metadata) * context->max_variables;
+ }
+ 
+-struct variable_info *variable_index_find(
+-	struct variable_index *context,
++const struct variable_info *variable_index_find(
++	const struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+ 	const int16_t *name)
+ {
+-	struct variable_info *result = NULL;
++	const struct variable_info *result = NULL;
+ 	int pos = find_variable(context, guid, name_size, name);
+ 
+ 	if (pos >= 0) {
+@@ -149,13 +149,13 @@ struct variable_info *variable_index_find(
+ 	return result;
+ }
+ 
+-struct variable_info *variable_index_find_next(
++const struct variable_info *variable_index_find_next(
+ 	const struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+ 	const int16_t *name)
+ {
+-	struct variable_info *result = NULL;
++	const struct variable_info *result = NULL;
+ 
+ 	if (name_size >= sizeof(int16_t)) {
+ 
+@@ -263,11 +263,12 @@ static struct variable_entry *add_entry(
+ 	return entry;
+ }
+ 
+-struct variable_info *variable_index_add_entry(
++const struct variable_info *variable_index_add_variable(
+ 	struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+-	const int16_t *name)
++	const int16_t *name,
++	uint32_t attributes)
+ {
+ 	struct variable_info *info = NULL;
+ 	struct variable_entry *entry = add_entry(context, guid, name_size, name);
+@@ -275,41 +276,40 @@ struct variable_info *variable_index_add_entry(
+ 	if (entry) {
+ 
+ 		info = &entry->info;
++
++		info->metadata.attributes = attributes;
++		info->is_variable_set = true;
++
++		mark_dirty(entry);
+ 	}
+ 
+ 	return info;
+ }
+ 
+-void variable_index_remove_unused_entry(
++const struct variable_info *variable_index_add_constraints(
+ 	struct variable_index *context,
+-	struct variable_info *info)
++	const EFI_GUID *guid,
++	size_t name_size,
++	const int16_t *name,
++	const struct variable_constraints *constraints)
+ {
+-	if (info &&
+-		!info->is_constraints_set &&
+-		!info->is_variable_set) {
+-
+-		struct variable_entry *entry = containing_entry(info);
+-		entry->in_use = false;
++	struct variable_info *info = NULL;
++	struct variable_entry *entry = add_entry(context, guid, name_size, name);
+ 
+-		memset(info, 0, sizeof(struct variable_info));
+-	}
+-}
++	if (entry) {
+ 
+-void variable_index_set_variable(
+-	struct variable_info *info,
+-	uint32_t attributes)
+-{
+-	struct variable_entry *entry = containing_entry(info);
++		info = &entry->info;
+ 
+-	info->metadata.attributes = attributes;
+-	info->is_variable_set = true;
++		info->check_constraints = *constraints;
++		info->is_constraints_set = true;
++	}
+ 
+-	mark_dirty(entry);
++	return info;
+ }
+ 
+-void variable_index_clear_variable(
++void variable_index_remove_variable(
+ 	struct variable_index *context,
+-	struct variable_info *info)
++	const struct variable_info *info)
+ {
+ 	if (info) {
+ 
+@@ -318,17 +318,48 @@ void variable_index_clear_variable(
+ 
+ 		/* Mark variable as no longer set */
+ 		entry->info.is_variable_set = false;
++
++		/* Entry may still be needed if check constraints were set */
++		entry->in_use = info->is_constraints_set;
++
++		if (!entry->in_use) {
++
++			/* Entry not needed so wipe */
++			memset(&entry->info, 0, sizeof(struct variable_info));
++		}
+ 	}
+ }
+ 
+-void variable_index_set_constraints(
+-	struct variable_info *info,
++void variable_index_update_variable(
++	const struct variable_info *info,
++	uint32_t attributes)
++{
++	if (info) {
++
++		struct variable_info *modified_info = (struct variable_info*)info;
++		struct variable_entry *entry = containing_entry(modified_info);
++
++		if (!modified_info->is_variable_set ||
++			(attributes != modified_info->metadata.attributes)) {
++
++			/* The update changes the variable_info state */
++			modified_info->is_variable_set = true;
++			modified_info->metadata.attributes = attributes;
++			mark_dirty(entry);
++		}
++	}
++}
++
++void variable_index_update_constraints(
++	const struct variable_info *info,
+ 	const struct variable_constraints *constraints)
+ {
+ 	if (info) {
+ 
+-		info->check_constraints = *constraints;
+-		info->is_constraints_set = true;
++		struct variable_info *modified_info = (struct variable_info*)info;
++
++		modified_info->check_constraints = *constraints;
++		modified_info->is_constraints_set = true;
+ 	}
+ }
+ 
+diff --git a/components/service/smm_variable/backend/variable_index.h b/components/service/smm_variable/backend/variable_index.h
+index 63f42ab6..e109d0d1 100644
+--- a/components/service/smm_variable/backend/variable_index.h
++++ b/components/service/smm_variable/backend/variable_index.h
+@@ -119,8 +119,8 @@ size_t variable_index_max_dump_size(
+  *
+  * @return     Pointer to variable_info or NULL
+  */
+-struct variable_info *variable_index_find(
+-	struct variable_index *context,
++const struct variable_info *variable_index_find(
++	const struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+ 	const int16_t *name);
+@@ -135,76 +135,78 @@ struct variable_info *variable_index_find(
+  *
+  * @return     Pointer to variable_info or NULL
+  */
+-struct variable_info *variable_index_find_next(
++const struct variable_info *variable_index_find_next(
+ 	const struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+ 	const int16_t *name);
+ 
+ /**
+- * @brief      Add a new entry to the index
+- *
+- * An entry is needed either when a new variable is created or
+- * when variable constraints are set for a variable that doesn't
+- * yet exist.
++ * @brief      Add a new variable to the index
+  *
+  * @param[in]  context variable_index
+  * @param[in]  guid The variable's guid
+  * @param[in]  name_size The name parameter's size
+  * @param[in]  name The variable's name
++ * @param[in]  attributes The variable's attributes
+  *
+  * @return     Pointer to variable_info or NULL
+  */
+-struct variable_info *variable_index_add_entry(
++const struct variable_info *variable_index_add_variable(
+ 	struct variable_index *context,
+ 	const EFI_GUID *guid,
+ 	size_t name_size,
+-	const int16_t *name);
++	const int16_t *name,
++	uint32_t attributes);
+ 
+ /**
+- * @brief      Remove an unused entry from the index
++ * @brief      Remove a variable from the index
+  *
+- * Removes an entry if it is not in use.
++ * Removes a variable from the index if it exists.
+  *
+  * @param[in]  context variable_index
+  * @param[in]  info The variable info corresponding to the entry to remove
+  */
+-void variable_index_remove_unused_entry(
++void variable_index_remove_variable(
+ 	struct variable_index *context,
+-	struct variable_info *info);
++	const struct variable_info *info);
+ 
+ /**
+- * @brief      Set a variable to the index
+- *
+- * An entry for the variable must already exist.
++ * @brief      Update a variable that's already in the index
+  *
+  * @param[in]  info variable info
+  * @param[in]  attributes The variable's attributes
+  */
+-void variable_index_set_variable(
+-	struct variable_info *info,
++void variable_index_update_variable(
++	const struct variable_info *info,
+ 	uint32_t attributes);
+ 
+ /**
+- * @brief      Clear a variable from the index
+- *
+- * Clears a variable from the index
++ * @brief      Add a new check constraints object to the index
+  *
+  * @param[in]  context variable_index
+- * @param[in]  info The variable info corresponding to the variable to clear
++ * @param[in]  guid The variable's guid
++ * @param[in]  name_size The name parameter's size
++ * @param[in]  name The variable's name
++ * @param[in]  constraints The check constraints
++ *
++ * @return     Pointer to variable_info or NULL
+  */
+-void variable_index_clear_variable(
++const struct variable_info *variable_index_add_constraints(
+ 	struct variable_index *context,
+-	struct variable_info *info);
++	const EFI_GUID *guid,
++	size_t name_size,
++	const int16_t *name,
++	const struct variable_constraints *constraints);
+ 
+ /**
+- * @brief      Set a check constraints object associated with a variavle
++ * @brief      Update variable constraints that are already in the index
+  *
+  * @param[in]  info variable info
+  * @param[in]  constraints The check constraints
+  */
+-void variable_index_set_constraints(
+-	struct variable_info *info,
++void variable_index_update_constraints(
++	const struct variable_info *info,
+ 	const struct variable_constraints *constraints);
+ 
+ /**
+diff --git a/components/service/smm_variable/backend/variable_index_iterator.c b/components/service/smm_variable/backend/variable_index_iterator.c
+index 8f8fc741..7cc6dc7a 100644
+--- a/components/service/smm_variable/backend/variable_index_iterator.c
++++ b/components/service/smm_variable/backend/variable_index_iterator.c
+@@ -31,10 +31,10 @@ bool variable_index_iterator_is_done(
+ 	return iter->current_pos >= iter->variable_index->max_variables;
+ }
+ 
+-struct variable_info *variable_index_iterator_current(
++const struct variable_info *variable_index_iterator_current(
+ 	const struct variable_index_iterator *iter)
+ {
+-	struct variable_info *current = NULL;
++	const struct variable_info *current = NULL;
+ 
+ 	if (!variable_index_iterator_is_done(iter)) {
+ 
+diff --git a/components/service/smm_variable/backend/variable_index_iterator.h b/components/service/smm_variable/backend/variable_index_iterator.h
+index 7ff77c50..f64a2c49 100644
+--- a/components/service/smm_variable/backend/variable_index_iterator.h
++++ b/components/service/smm_variable/backend/variable_index_iterator.h
+@@ -54,7 +54,7 @@ bool variable_index_iterator_is_done(
+  *
+  * @return     Pointer to variable_info or NULL
+  */
+-struct variable_info *variable_index_iterator_current(
++const struct variable_info *variable_index_iterator_current(
+ 	const struct variable_index_iterator *iter);
+ 
+ /**
+diff --git a/components/service/smm_variable/test/service/smm_variable_service_tests.cpp b/components/service/smm_variable/test/service/smm_variable_service_tests.cpp
+index 15556e9d..38c08ebe 100644
+--- a/components/service/smm_variable/test/service/smm_variable_service_tests.cpp
++++ b/components/service/smm_variable/test/service/smm_variable_service_tests.cpp
+@@ -249,30 +249,6 @@ TEST(SmmVariableServiceTests, setAndGet)
+ 	UNSIGNED_LONGS_EQUAL(set_data.size(), get_data.size());
+ 	LONGS_EQUAL(0, get_data.compare(set_data));
+ 
+-	/* Extend the variable using an append write */
+-	std::string append_data = " values added with append write";
+-
+-	efi_status = m_client->set_variable(
+-		m_common_guid,
+-		var_name,
+-		append_data,
+-		EFI_VARIABLE_APPEND_WRITE);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+-
+-	efi_status = m_client->get_variable(
+-		m_common_guid,
+-		var_name,
+-		get_data);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+-
+-	std::string appended_data = set_data + append_data;
+-
+-	/* Expect the append write operation to have extended the variable */
+-	UNSIGNED_LONGLONGS_EQUAL(appended_data.size(), get_data.size());
+-	LONGS_EQUAL(0, appended_data.compare(get_data));
+-
+ 	/* Expect remove to be permitted */
+ 	efi_status = m_client->remove_variable(m_common_guid, var_name);
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+@@ -303,30 +279,6 @@ TEST(SmmVariableServiceTests, setAndGetNv)
+ 	UNSIGNED_LONGS_EQUAL(set_data.size(), get_data.size());
+ 	LONGS_EQUAL(0, get_data.compare(set_data));
+ 
+-	/* Extend the variable using an append write */
+-	std::string append_data = " values added with append write";
+-
+-	efi_status = m_client->set_variable(
+-		m_common_guid,
+-		var_name,
+-		append_data,
+-		EFI_VARIABLE_NON_VOLATILE | EFI_VARIABLE_APPEND_WRITE);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+-
+-	efi_status = m_client->get_variable(
+-		m_common_guid,
+-		var_name,
+-		get_data);
+-
+-	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+-
+-	std::string appended_data = set_data + append_data;
+-
+-	/* Expect the append write operation to have extended the variable */
+-	UNSIGNED_LONGLONGS_EQUAL(appended_data.size(), get_data.size());
+-	LONGS_EQUAL(0, appended_data.compare(get_data));
+-
+ 	/* Expect remove to be permitted */
+ 	efi_status = m_client->remove_variable(m_common_guid, var_name);
+ 	UNSIGNED_LONGLONGS_EQUAL(EFI_SUCCESS, efi_status);
+diff --git a/protocols/service/smm_variable/parameters.h b/protocols/service/smm_variable/parameters.h
+index 233f301b..1f795a9b 100644
+--- a/protocols/service/smm_variable/parameters.h
++++ b/protocols/service/smm_variable/parameters.h
+@@ -47,9 +47,6 @@ typedef struct {
+ 	 EFI_VARIABLE_HARDWARE_ERROR_RECORD | \
+ 	 EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS | \
+ 	 EFI_VARIABLE_APPEND_WRITE)
+-#define	EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS_MASK \
+-	(EFI_VARIABLE_AUTHENTICATED_WRITE_ACCESS | \
+-	 EFI_VARIABLE_TIME_BASED_AUTHENTICATED_WRITE_ACCESS)
+ 
+ /**
+  * Parameter structure for SetVariable and GetVariable.