[PATCH v2 04/11] efi_loader: enable EFI runtime SetVariable()/GetVariable() using FF-A transport
Harsimran Singh Tungal
harsimransingh.tungal at arm.com
Thu May 14 14:49:17 CEST 2026
Route EFI runtime variable APIs through FF-A MM communication
Route EFI runtime variable services through the FF-A/MM backend in
lib/efi_loader/efi_variable_tee.c. After ExitBootServices(),
GetVariable(), SetVariable(), GetNextVariableName(), and
QueryVariableInfo() use the runtime entry points and continue to reach
the MM secure partition.
Keep the existing boot-time helpers unchanged and add runtime service
wrappers for variable access and property handling. Reuse the
runtime-safe setup_mm_hdr() and common mm_communicate() path, which
selects the FF-A transport appropriate for the current phase, and use
the EFI runtime-safe memory helpers in the runtime-only code.
Signed-off-by: Harsimran Singh Tungal <harsimransingh.tungal at arm.com>
---
Changelog:
===============
v2:
Simon:
- Cache attributes before reusing the FF-A shared buffer
- Move the read-only property check before `setup_mm_hdr()` in
efi_set_variable_runtime
- Drop the stale copied boot-path comment
- Split the `u16_strsize()` runtime annotation to a separate patch
lib/efi_loader/efi_variable_tee.c | 320 +++++++++++++++++++++++++++++-
1 file changed, 315 insertions(+), 5 deletions(-)
diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index ccd8d94a51e..8acd0ed127b 100644
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -698,6 +698,38 @@ out:
return ret;
}
+static efi_status_t __efi_runtime set_property_int_runtime(const u16 *variable_name,
+ efi_uintn_t name_size,
+ const efi_guid_t *vendor,
+ struct var_check_property *var_property)
+{
+ struct smm_variable_var_check_property *smm_property;
+ efi_uintn_t payload_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ payload_size = sizeof(*smm_property) + name_size;
+ if (payload_size > max_payload_size) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+ comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+ SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET,
+ &ret);
+ if (!comm_buf)
+ return ret;
+
+ efi_memcpy_runtime(&smm_property->guid, vendor, sizeof(*vendor));
+ smm_property->name_size = name_size;
+ efi_memcpy_runtime(&smm_property->property, var_property,
+ sizeof(smm_property->property));
+ efi_memcpy_runtime(smm_property->name, variable_name, name_size);
+
+ ret = mm_communicate(comm_buf, payload_size);
+
+ return ret;
+}
+
static efi_status_t get_property_int(const u16 *variable_name,
efi_uintn_t name_size,
const efi_guid_t *vendor,
@@ -743,6 +775,49 @@ out:
return ret;
}
+static efi_status_t __efi_runtime get_property_int_runtime(const u16 *variable_name,
+ efi_uintn_t name_size,
+ const efi_guid_t *vendor,
+ struct var_check_property *var_property)
+{
+ struct smm_variable_var_check_property *smm_property;
+ efi_uintn_t payload_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ efi_memset_runtime(var_property, 0, sizeof(*var_property));
+ payload_size = sizeof(*smm_property) + name_size;
+ if (payload_size > max_payload_size) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+ comm_buf = setup_mm_hdr((void **)&smm_property, payload_size,
+ SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET,
+ &ret);
+ if (!comm_buf)
+ return ret;
+
+ efi_memcpy_runtime(&smm_property->guid, vendor, sizeof(smm_property->guid));
+ smm_property->name_size = name_size;
+ efi_memcpy_runtime(smm_property->name, variable_name, name_size);
+
+ ret = mm_communicate(comm_buf, payload_size);
+ /*
+ * Currently only R/O property is supported in StMM.
+ * Variables that are not set to R/O will not set the property in StMM
+ * and the call will return EFI_NOT_FOUND. We are setting the
+ * properties to 0x0 so checking against that is enough for the
+ * EFI_NOT_FOUND case.
+ */
+ if (ret == EFI_NOT_FOUND)
+ ret = EFI_SUCCESS;
+ if (ret != EFI_SUCCESS)
+ return ret;
+ efi_memcpy_runtime(var_property, &smm_property->property, sizeof(*var_property));
+
+ return ret;
+}
+
efi_status_t efi_get_variable_int(const u16 *variable_name,
const efi_guid_t *vendor,
u32 *attributes, efi_uintn_t *data_size,
@@ -830,6 +905,95 @@ out:
return ret;
}
+efi_status_t __efi_runtime efi_get_variable_runtime(u16 *variable_name,
+ const efi_guid_t *vendor,
+ u32 *attributes,
+ efi_uintn_t *data_size,
+ void *data)
+{
+ struct var_check_property var_property;
+ struct smm_variable_access *var_acc;
+ efi_uintn_t payload_size;
+ efi_uintn_t name_size;
+ efi_uintn_t tmp_dsize;
+ u8 *comm_buf = NULL;
+ efi_status_t ret, tmp;
+ u32 var_attr = 0;
+
+ if (!variable_name || !vendor || !data_size) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+
+ /* Check payload size */
+ name_size = u16_strsize(variable_name);
+ if (name_size > max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+
+ /* Trim output buffer size */
+ tmp_dsize = *data_size;
+ if (name_size + tmp_dsize >
+ max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE) {
+ tmp_dsize = max_payload_size -
+ MM_VARIABLE_ACCESS_HEADER_SIZE -
+ name_size;
+ }
+
+ /* Get communication buffer and initialize header */
+ payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + tmp_dsize;
+ comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
+ SMM_VARIABLE_FUNCTION_GET_VARIABLE, &ret);
+ if (!comm_buf)
+ return ret;
+
+ /* Fill in contents */
+ efi_memcpy_runtime(&var_acc->guid, vendor, sizeof(var_acc->guid));
+ var_acc->data_size = tmp_dsize;
+ var_acc->name_size = name_size;
+ var_acc->attr = attributes ? *attributes : 0;
+ efi_memcpy_runtime(var_acc->name, variable_name, name_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret != EFI_SUCCESS && ret != EFI_BUFFER_TOO_SMALL)
+ return ret;
+
+ /* Update with reported data size for trimmed case */
+ *data_size = var_acc->data_size;
+ if (attributes)
+ var_attr = var_acc->attr;
+
+ /* Copy the data if ret is EFI_SUCCESS */
+ if (ret == EFI_SUCCESS) {
+ if (data)
+ efi_memcpy_runtime(data, (u8 *)var_acc->name + var_acc->name_size,
+ var_acc->data_size);
+ else
+ ret = EFI_INVALID_PARAMETER;
+ }
+
+ /*
+ * UEFI > 2.7 needs the attributes set even if the buffer is
+ * smaller
+ */
+ if (attributes) {
+ tmp = get_property_int_runtime(variable_name, name_size, vendor,
+ &var_property);
+ if (tmp != EFI_SUCCESS) {
+ ret = tmp;
+ return ret;
+ }
+ *attributes = var_attr;
+ if (var_property.property &
+ VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)
+ *attributes |= EFI_VARIABLE_READ_ONLY;
+ }
+
+ return ret;
+}
+
efi_status_t efi_get_next_variable_name_int(efi_uintn_t *variable_name_size,
u16 *variable_name,
efi_guid_t *guid)
@@ -894,6 +1058,68 @@ out:
return ret;
}
+efi_status_t __efi_runtime efi_get_next_variable_name_runtime(efi_uintn_t *variable_name_size,
+ u16 *variable_name,
+ efi_guid_t *guid)
+{
+ struct smm_variable_getnext *var_getnext;
+ efi_uintn_t payload_size;
+ efi_uintn_t out_name_size;
+ efi_uintn_t in_name_size;
+ u8 *comm_buf = NULL;
+ efi_status_t ret;
+
+ if (!variable_name_size || !variable_name || !guid) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+
+ out_name_size = *variable_name_size;
+ in_name_size = u16_strsize(variable_name);
+
+ if (out_name_size < in_name_size) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+
+ if (in_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE) {
+ ret = EFI_INVALID_PARAMETER;
+ return ret;
+ }
+
+ /* Trim output buffer size */
+ if (out_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
+ out_name_size = max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE;
+
+ payload_size = MM_VARIABLE_GET_NEXT_HEADER_SIZE + out_name_size;
+ comm_buf = setup_mm_hdr((void **)&var_getnext, payload_size,
+ SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME,
+ &ret);
+ if (!comm_buf)
+ return ret;
+
+ /* Fill in contents */
+ efi_memcpy_runtime(&var_getnext->guid, guid, sizeof(*guid));
+ var_getnext->name_size = out_name_size;
+ efi_memcpy_runtime(var_getnext->name, variable_name, in_name_size);
+ efi_memset_runtime((u8 *)var_getnext->name + in_name_size, 0x0,
+ out_name_size - in_name_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
+ /* Update with reported data size for trimmed case */
+ *variable_name_size = var_getnext->name_size;
+ }
+ if (ret != EFI_SUCCESS)
+ return ret;
+
+ efi_memcpy_runtime(guid, &var_getnext->guid, sizeof(*guid));
+ efi_memcpy_runtime(variable_name, var_getnext->name, var_getnext->name_size);
+
+ return ret;
+}
+
efi_status_t efi_set_variable_int(const u16 *variable_name,
const efi_guid_t *vendor, u32 attributes,
efi_uintn_t data_size, const void *data,
@@ -1036,11 +1262,11 @@ out:
*
* @attributes: bitmask to select variables to be
* queried
- * @maximum_variable_storage_size: maximum size of storage area for the
+ * @max_variable_storage_size: maximum size of storage area for the
* selected variable types
- * @remaining_variable_storage_size: remaining size of storage are for the
+ * @remain_variable_storage_size: remaining size of storage are for the
* selected variable types
- * @maximum_variable_size: maximum size of a variable of the
+ * @max_variable_size: maximum size of a variable of the
* selected type
* Return: status code
*/
@@ -1049,7 +1275,33 @@ efi_query_variable_info_runtime(u32 attributes, u64 *max_variable_storage_size,
u64 *remain_variable_storage_size,
u64 *max_variable_size)
{
- return EFI_UNSUPPORTED;
+ struct smm_variable_query_info *mm_query_info;
+ efi_uintn_t payload_size;
+ efi_status_t ret;
+ u8 *comm_buf;
+
+ if (!max_variable_storage_size ||
+ !remain_variable_storage_size ||
+ !max_variable_size || !attributes)
+ return EFI_INVALID_PARAMETER;
+
+ payload_size = sizeof(*mm_query_info);
+ comm_buf = setup_mm_hdr((void **)&mm_query_info, payload_size,
+ SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO,
+ &ret);
+ if (!comm_buf)
+ return ret;
+
+ mm_query_info->attr = attributes;
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret != EFI_SUCCESS)
+ return ret;
+ *max_variable_storage_size = mm_query_info->max_variable_storage;
+ *remain_variable_storage_size =
+ mm_query_info->remaining_variable_storage;
+ *max_variable_size = mm_query_info->max_variable_size;
+
+ return ret;
}
/**
@@ -1067,7 +1319,65 @@ efi_set_variable_runtime(u16 *variable_name, const efi_guid_t *guid,
u32 attributes, efi_uintn_t data_size,
const void *data)
{
- return EFI_UNSUPPORTED;
+ efi_status_t ret, mm_communicate_ret = EFI_SUCCESS;
+ struct var_check_property var_property;
+ struct smm_variable_access *var_acc;
+ efi_uintn_t payload_size;
+ efi_uintn_t name_size;
+ u8 *comm_buf = NULL;
+ bool ro;
+
+ if (!variable_name || variable_name[0] == 0 || !guid)
+ return EFI_INVALID_PARAMETER;
+
+ if (data_size > 0 && !data)
+ return EFI_INVALID_PARAMETER;
+
+ /* Check payload size */
+ name_size = u16_strsize(variable_name);
+ payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
+ if (payload_size > max_payload_size)
+ return EFI_INVALID_PARAMETER;
+
+ ro = !!(attributes & EFI_VARIABLE_READ_ONLY);
+ attributes &= EFI_VARIABLE_MASK;
+
+ ret = get_property_int_runtime(variable_name, name_size, guid,
+ &var_property);
+ if (ret != EFI_SUCCESS)
+ return ret;
+
+ if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)
+ return EFI_WRITE_PROTECTED;
+
+ comm_buf = setup_mm_hdr((void **)&var_acc, payload_size,
+ SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
+ if (!comm_buf)
+ return ret;
+
+ /* Fill in contents */
+ efi_memcpy_runtime(&var_acc->guid, guid, sizeof(*guid));
+ var_acc->data_size = data_size;
+ var_acc->name_size = name_size;
+ var_acc->attr = attributes;
+ efi_memcpy_runtime(var_acc->name, variable_name, name_size);
+ efi_memcpy_runtime((u8 *)var_acc->name + name_size, data, data_size);
+
+ /* Communicate */
+ ret = mm_communicate(comm_buf, payload_size);
+ if (ret != EFI_SUCCESS)
+ mm_communicate_ret = ret;
+
+ if (ro && !(var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY)) {
+ var_property.revision = VAR_CHECK_VARIABLE_PROPERTY_REVISION;
+ var_property.property |= VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY;
+ var_property.attributes = attributes;
+ var_property.minsize = 1;
+ var_property.maxsize = var_acc->data_size;
+ ret = set_property_int_runtime(variable_name, name_size, guid, &var_property);
+ }
+
+ return (mm_communicate_ret == EFI_SUCCESS) ? ret : mm_communicate_ret;
}
/**
--
2.34.1
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