Merge tag 'efi-next-for-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi

Pull EFI updates from Ard Biesheuvel:

 - Fix a syzbot reported issue in efivarfs where concurrent accesses to
   the file system resulted in list corruption

 - Add support for accessing EFI variables via the TEE subsystem (and a
   trusted application in the secure world) instead of via EFI runtime
   firmware running in the OS's execution context

 - Avoid linker tricks to discover the image base on LoongArch

* tag 'efi-next-for-v6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  efi: memmap: fix kernel-doc warnings
  efi/loongarch: Directly position the loaded image file
  efivarfs: automatically update super block flag
  efi: Add tee-based EFI variable driver
  efi: Add EFI_ACCESS_DENIED status code
  efi: expose efivar generic ops register function
  efivarfs: Move efivarfs list into superblock s_fs_info
  efivarfs: Free s_fs_info on unmount
  efivarfs: Move efivar availability check into FS context init
  efivarfs: force RO when remounting if SetVariable is not supported

10 files changed, 912 insertions, 9 deletions

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index cb374b2da9b7..72f2537d90ca 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -301,3 +301,18 @@ config UEFI_CPER_X86
 	bool
 	depends on UEFI_CPER && X86
 	default y
+
+config TEE_STMM_EFI
+	tristate "TEE-based EFI runtime variable service driver"
+	depends on EFI && OPTEE
+	help
+	  Select this config option if TEE is compiled to include StandAloneMM
+	  as a separate secure partition. It has the ability to check and store
+	  EFI variables on an RPMB or any other non-volatile medium used by
+	  StandAloneMM.
+
+	  Enabling this will change the EFI runtime services from the firmware
+	  provided functions to TEE calls.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called tee_stmm_efi.
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index e489fefd23da..a2d0009560d0 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -42,3 +42,4 @@ obj-$(CONFIG_EFI_EARLYCON)		+= earlycon.o
 obj-$(CONFIG_UEFI_CPER_ARM)		+= cper-arm.o
 obj-$(CONFIG_UEFI_CPER_X86)		+= cper-x86.o
 obj-$(CONFIG_UNACCEPTED_MEMORY)		+= unaccepted_memory.o
+obj-$(CONFIG_TEE_STMM_EFI)		+= stmm/tee_stmm_efi.o
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 9d3910d1abe1..4fcda50acfa4 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -32,6 +32,7 @@
 #include <linux/ucs2_string.h>
 #include <linux/memblock.h>
 #include <linux/security.h>
+#include <linux/notifier.h>
 
 #include <asm/early_ioremap.h>
 
@@ -187,6 +188,9 @@ static const struct attribute_group efi_subsys_attr_group = {
 	.is_visible = efi_attr_is_visible,
 };
 
+struct blocking_notifier_head efivar_ops_nh;
+EXPORT_SYMBOL_GPL(efivar_ops_nh);
+
 static struct efivars generic_efivars;
 static struct efivar_operations generic_ops;
 
@@ -231,6 +235,18 @@ static void generic_ops_unregister(void)
 	efivars_unregister(&generic_efivars);
 }
 
+void efivars_generic_ops_register(void)
+{
+	generic_ops_register();
+}
+EXPORT_SYMBOL_GPL(efivars_generic_ops_register);
+
+void efivars_generic_ops_unregister(void)
+{
+	generic_ops_unregister();
+}
+EXPORT_SYMBOL_GPL(efivars_generic_ops_unregister);
+
 #ifdef CONFIG_EFI_CUSTOM_SSDT_OVERLAYS
 #define EFIVAR_SSDT_NAME_MAX	16UL
 static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
@@ -419,6 +435,8 @@ static int __init efisubsys_init(void)
 		platform_device_register_simple("efivars", 0, NULL, 0);
 	}
 
+	BLOCKING_INIT_NOTIFIER_HEAD(&efivar_ops_nh);
+
 	error = sysfs_create_group(efi_kobj, &efi_subsys_attr_group);
 	if (error) {
 		pr_err("efi: Sysfs attribute export failed with error %d.\n",
diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
index d6ec5d4b8dbe..736b6aae323d 100644
--- a/drivers/firmware/efi/libstub/loongarch-stub.c
+++ b/drivers/firmware/efi/libstub/loongarch-stub.c
@@ -8,10 +8,10 @@
 #include <asm/efi.h>
 #include <asm/addrspace.h>
 #include "efistub.h"
+#include "loongarch-stub.h"
 
 extern int kernel_asize;
 extern int kernel_fsize;
-extern int kernel_offset;
 extern int kernel_entry;
 
 efi_status_t handle_kernel_image(unsigned long *image_addr,
@@ -24,7 +24,7 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	efi_status_t status;
 	unsigned long kernel_addr = 0;
 
-	kernel_addr = (unsigned long)&kernel_offset - kernel_offset;
+	kernel_addr = (unsigned long)image->image_base;
 
 	status = efi_relocate_kernel(&kernel_addr, kernel_fsize, kernel_asize,
 		     EFI_KIMG_PREFERRED_ADDRESS, efi_get_kimg_min_align(), 0x0);
@@ -35,9 +35,10 @@ efi_status_t handle_kernel_image(unsigned long *image_addr,
 	return status;
 }
 
-unsigned long kernel_entry_address(unsigned long kernel_addr)
+unsigned long kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image)
 {
-	unsigned long base = (unsigned long)&kernel_offset - kernel_offset;
+	unsigned long base = (unsigned long)image->image_base;
 
 	return (unsigned long)&kernel_entry - base + kernel_addr;
 }
diff --git a/drivers/firmware/efi/libstub/loongarch-stub.h b/drivers/firmware/efi/libstub/loongarch-stub.h
new file mode 100644
index 000000000000..cd015955a015
--- /dev/null
+++ b/drivers/firmware/efi/libstub/loongarch-stub.h
@@ -0,0 +1,4 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+unsigned long kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image);
diff --git a/drivers/firmware/efi/libstub/loongarch.c b/drivers/firmware/efi/libstub/loongarch.c
index 0e0aa6cda73f..684c9354637c 100644
--- a/drivers/firmware/efi/libstub/loongarch.c
+++ b/drivers/firmware/efi/libstub/loongarch.c
@@ -8,6 +8,7 @@
 #include <asm/efi.h>
 #include <asm/addrspace.h>
 #include "efistub.h"
+#include "loongarch-stub.h"
 
 typedef void __noreturn (*kernel_entry_t)(bool efi, unsigned long cmdline,
 					  unsigned long systab);
@@ -37,7 +38,8 @@ static efi_status_t exit_boot_func(struct efi_boot_memmap *map, void *priv)
 	return EFI_SUCCESS;
 }
 
-unsigned long __weak kernel_entry_address(unsigned long kernel_addr)
+unsigned long __weak kernel_entry_address(unsigned long kernel_addr,
+		efi_loaded_image_t *image)
 {
 	return *(unsigned long *)(kernel_addr + 8) - VMLINUX_LOAD_ADDRESS + kernel_addr;
 }
@@ -73,7 +75,7 @@ efi_status_t efi_boot_kernel(void *handle, efi_loaded_image_t *image,
 	csr_write64(CSR_DMW0_INIT, LOONGARCH_CSR_DMWIN0);
 	csr_write64(CSR_DMW1_INIT, LOONGARCH_CSR_DMWIN1);
 
-	real_kernel_entry = (void *)kernel_entry_address(kernel_addr);
+	real_kernel_entry = (void *)kernel_entry_address(kernel_addr, image);
 
 	real_kernel_entry(true, (unsigned long)cmdline_ptr,
 			  (unsigned long)efi_system_table);
diff --git a/drivers/firmware/efi/memmap.c b/drivers/firmware/efi/memmap.c
index a1180461a445..3365944f7965 100644
--- a/drivers/firmware/efi/memmap.c
+++ b/drivers/firmware/efi/memmap.c
@@ -32,7 +32,7 @@
  * space isn't setup.  Once the kernel is fully booted we can fallback
  * to the more robust memremap*() API.
  *
- * Returns zero on success, a negative error code on failure.
+ * Returns: zero on success, a negative error code on failure.
  */
 int __init __efi_memmap_init(struct efi_memory_map_data *data)
 {
@@ -77,6 +77,8 @@ int __init __efi_memmap_init(struct efi_memory_map_data *data)
  *
  * Use early_memremap() to map the passed in EFI memory map and assign
  * it to efi.memmap.
+ *
+ * Returns: zero on success, a negative error code on failure.
  */
 int __init efi_memmap_init_early(struct efi_memory_map_data *data)
 {
@@ -107,7 +109,7 @@ void __init efi_memmap_unmap(void)
 
 /**
  * efi_memmap_init_late - Map efi.memmap with memremap()
- * @phys_addr: Physical address of the new EFI memory map
+ * @addr: Physical address of the new EFI memory map
  * @size: Size in bytes of the new EFI memory map
  *
  * Setup a mapping of the EFI memory map using ioremap_cache(). This
@@ -126,7 +128,7 @@ void __init efi_memmap_unmap(void)
  * runtime so that things like efi_mem_desc_lookup() and
  * efi_mem_attributes() always work.
  *
- * Returns zero on success, a negative error code on failure.
+ * Returns: zero on success, a negative error code on failure.
  */
 int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
 {
diff --git a/drivers/firmware/efi/stmm/mm_communication.h b/drivers/firmware/efi/stmm/mm_communication.h
new file mode 100644
index 000000000000..52a1f32cd1eb
--- /dev/null
+++ b/drivers/firmware/efi/stmm/mm_communication.h
@@ -0,0 +1,236 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ *  Headers for EFI variable service via StandAloneMM, EDK2 application running
+ *  in OP-TEE. Most of the structs and defines resemble the EDK2 naming.
+ *
+ *  Copyright (c) 2017, Intel Corporation. All rights reserved.
+ *  Copyright (C) 2020 Linaro Ltd.
+ */
+
+#ifndef _MM_COMMUNICATION_H_
+#define _MM_COMMUNICATION_H_
+
+/*
+ * Interface to the pseudo Trusted Application (TA), which provides a
+ * communication channel with the Standalone MM (Management Mode)
+ * Secure Partition running at Secure-EL0
+ */
+
+#define PTA_STMM_CMD_COMMUNICATE 0
+
+/*
+ * Defined in OP-TEE, this UUID is used to identify the pseudo-TA.
+ * OP-TEE is using big endian GUIDs while UEFI uses little endian ones
+ */
+#define PTA_STMM_UUID \
+	UUID_INIT(0xed32d533, 0x99e6, 0x4209, \
+		  0x9c, 0xc0, 0x2d, 0x72, 0xcd, 0xd9, 0x98, 0xa7)
+
+#define EFI_MM_VARIABLE_GUID \
+	EFI_GUID(0xed32d533, 0x99e6, 0x4209, \
+		 0x9c, 0xc0, 0x2d, 0x72, 0xcd, 0xd9, 0x98, 0xa7)
+
+/**
+ * struct efi_mm_communicate_header - Header used for SMM variable communication
+
+ * @header_guid:  header use for disambiguation of content
+ * @message_len:  length of the message. Does not include the size of the
+ *                header
+ * @data:         payload of the message
+ *
+ * Defined in the PI spec as EFI_MM_COMMUNICATE_HEADER.
+ * To avoid confusion in interpreting frames, the communication buffer should
+ * always begin with efi_mm_communicate_header.
+ */
+struct efi_mm_communicate_header {
+	efi_guid_t header_guid;
+	size_t     message_len;
+	u8         data[];
+} __packed;
+
+#define MM_COMMUNICATE_HEADER_SIZE \
+	(sizeof(struct efi_mm_communicate_header))
+
+/* SPM return error codes */
+#define ARM_SVC_SPM_RET_SUCCESS               0
+#define ARM_SVC_SPM_RET_NOT_SUPPORTED        -1
+#define ARM_SVC_SPM_RET_INVALID_PARAMS       -2
+#define ARM_SVC_SPM_RET_DENIED               -3
+#define ARM_SVC_SPM_RET_NO_MEMORY            -5
+
+#define SMM_VARIABLE_FUNCTION_GET_VARIABLE  1
+/*
+ * The payload for this function is
+ * SMM_VARIABLE_COMMUNICATE_GET_NEXT_VARIABLE_NAME.
+ */
+#define SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME  2
+/*
+ * The payload for this function is SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE.
+ */
+#define SMM_VARIABLE_FUNCTION_SET_VARIABLE  3
+/*
+ * The payload for this function is
+ * SMM_VARIABLE_COMMUNICATE_QUERY_VARIABLE_INFO.
+ */
+#define SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO  4
+/*
+ * It is a notify event, no extra payload for this function.
+ */
+#define SMM_VARIABLE_FUNCTION_READY_TO_BOOT  5
+/*
+ * It is a notify event, no extra payload for this function.
+ */
+#define SMM_VARIABLE_FUNCTION_EXIT_BOOT_SERVICE  6
+/*
+ * The payload for this function is VARIABLE_INFO_ENTRY.
+ * The GUID in EFI_SMM_COMMUNICATE_HEADER is gEfiSmmVariableProtocolGuid.
+ */
+#define SMM_VARIABLE_FUNCTION_GET_STATISTICS  7
+/*
+ * The payload for this function is SMM_VARIABLE_COMMUNICATE_LOCK_VARIABLE
+ */
+#define SMM_VARIABLE_FUNCTION_LOCK_VARIABLE   8
+
+#define SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_SET  9
+
+#define SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET  10
+
+#define SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE  11
+/*
+ * The payload for this function is
+ * SMM_VARIABLE_COMMUNICATE_RUNTIME_VARIABLE_CACHE_CONTEXT
+ */
+#define SMM_VARIABLE_FUNCTION_INIT_RUNTIME_VARIABLE_CACHE_CONTEXT 12
+
+#define SMM_VARIABLE_FUNCTION_SYNC_RUNTIME_CACHE  13
+/*
+ * The payload for this function is
+ * SMM_VARIABLE_COMMUNICATE_GET_RUNTIME_CACHE_INFO
+ */
+#define SMM_VARIABLE_FUNCTION_GET_RUNTIME_CACHE_INFO  14
+
+/**
+ * struct smm_variable_communicate_header - Used for SMM variable communication
+
+ * @function:     function to call in Smm.
+ * @ret_status:   return status
+ * @data:         payload
+ */
+struct smm_variable_communicate_header {
+	size_t  function;
+	efi_status_t ret_status;
+	u8 data[];
+};
+
+#define MM_VARIABLE_COMMUNICATE_SIZE \
+	(sizeof(struct smm_variable_communicate_header))
+
+/**
+ * struct smm_variable_access - Used to communicate with StMM by
+ *                              SetVariable and GetVariable.
+
+ * @guid:         vendor GUID
+ * @data_size:    size of EFI variable data
+ * @name_size:    size of EFI name
+ * @attr:         attributes
+ * @name:         variable name
+ *
+ */
+struct smm_variable_access {
+	efi_guid_t  guid;
+	size_t data_size;
+	size_t name_size;
+	u32 attr;
+	u16 name[];
+};
+
+#define MM_VARIABLE_ACCESS_HEADER_SIZE \
+	(sizeof(struct smm_variable_access))
+/**
+ * struct smm_variable_payload_size - Used to get the max allowed
+ *                                    payload used in StMM.
+ *
+ * @size:  size to fill in
+ *
+ */
+struct smm_variable_payload_size {
+	size_t size;
+};
+
+/**
+ * struct smm_variable_getnext - Used to communicate with StMM for
+ *                               GetNextVariableName.
+ *
+ * @guid:       vendor GUID
+ * @name_size:  size of the name of the variable
+ * @name:       variable name
+ *
+ */
+struct smm_variable_getnext {
+	efi_guid_t  guid;
+	size_t name_size;
+	u16         name[];
+};
+
+#define MM_VARIABLE_GET_NEXT_HEADER_SIZE \
+	(sizeof(struct smm_variable_getnext))
+
+/**
+ * struct smm_variable_query_info - Used to communicate with StMM for
+ *                                  QueryVariableInfo.
+ *
+ * @max_variable_storage:        max available storage
+ * @remaining_variable_storage:  remaining available storage
+ * @max_variable_size:           max variable supported size
+ * @attr:                        attributes to query storage for
+ *
+ */
+struct smm_variable_query_info {
+	u64 max_variable_storage;
+	u64 remaining_variable_storage;
+	u64 max_variable_size;
+	u32 attr;
+};
+
+#define VAR_CHECK_VARIABLE_PROPERTY_REVISION 0x0001
+#define VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY BIT(0)
+/**
+ * struct var_check_property - Used to store variable properties in StMM
+ *
+ * @revision:   magic revision number for variable property checking
+ * @property:   properties mask for the variable used in StMM.
+ *              Currently RO flag is supported
+ * @attributes: variable attributes used in StMM checking when properties
+ *              for a variable are enabled
+ * @minsize:    minimum allowed size for variable payload checked against
+ *              smm_variable_access->datasize in StMM
+ * @maxsize:    maximum allowed size for variable payload checked against
+ *              smm_variable_access->datasize in StMM
+ *
+ */
+struct var_check_property {
+	u16 revision;
+	u16 property;
+	u32 attributes;
+	size_t minsize;
+	size_t maxsize;
+};
+
+/**
+ * struct smm_variable_var_check_property - Used to communicate variable
+ *                                          properties with StMM
+ *
+ * @guid:       vendor GUID
+ * @name_size:  size of EFI name
+ * @property:   variable properties struct
+ * @name:       variable name
+ *
+ */
+struct smm_variable_var_check_property {
+	efi_guid_t guid;
+	size_t name_size;
+	struct var_check_property property;
+	u16 name[];
+};
+
+#endif /* _MM_COMMUNICATION_H_ */
diff --git a/drivers/firmware/efi/stmm/tee_stmm_efi.c b/drivers/firmware/efi/stmm/tee_stmm_efi.c
new file mode 100644
index 000000000000..f741ca279052
--- /dev/null
+++ b/drivers/firmware/efi/stmm/tee_stmm_efi.c
@@ -0,0 +1,616 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ *  EFI variable service via TEE
+ *
+ *  Copyright (C) 2022 Linaro
+ */
+
+#include <linux/efi.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/tee.h>
+#include <linux/tee_drv.h>
+#include <linux/ucs2_string.h>
+#include "mm_communication.h"
+
+static struct efivars tee_efivars;
+static struct efivar_operations tee_efivar_ops;
+
+static size_t max_buffer_size; /* comm + var + func + data */
+static size_t max_payload_size; /* func + data */
+
+struct tee_stmm_efi_private {
+	struct tee_context *ctx;
+	u32 session;
+	struct device *dev;
+};
+
+static struct tee_stmm_efi_private pvt_data;
+
+/* UUID of the stmm PTA */
+static const struct tee_client_device_id tee_stmm_efi_id_table[] = {
+	{PTA_STMM_UUID},
+	{}
+};
+
+static int tee_ctx_match(struct tee_ioctl_version_data *ver, const void *data)
+{
+	/* currently only OP-TEE is supported as a communication path */
+	if (ver->impl_id == TEE_IMPL_ID_OPTEE)
+		return 1;
+	else
+		return 0;
+}
+
+/**
+ * tee_mm_communicate() - Pass a buffer to StandaloneMM running in TEE
+ *
+ * @comm_buf:		locally allocated communication buffer
+ * @dsize:		buffer size
+ * Return:		status code
+ */
+static efi_status_t tee_mm_communicate(void *comm_buf, size_t dsize)
+{
+	size_t buf_size;
+	struct efi_mm_communicate_header *mm_hdr;
+	struct tee_ioctl_invoke_arg arg;
+	struct tee_param param[4];
+	struct tee_shm *shm = NULL;
+	int rc;
+
+	if (!comm_buf)
+		return EFI_INVALID_PARAMETER;
+
+	mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+	buf_size = mm_hdr->message_len + sizeof(efi_guid_t) + sizeof(size_t);
+
+	if (dsize != buf_size)
+		return EFI_INVALID_PARAMETER;
+
+	shm = tee_shm_register_kernel_buf(pvt_data.ctx, comm_buf, buf_size);
+	if (IS_ERR(shm)) {
+		dev_err(pvt_data.dev, "Unable to register shared memory\n");
+		return EFI_UNSUPPORTED;
+	}
+
+	memset(&arg, 0, sizeof(arg));
+	arg.func = PTA_STMM_CMD_COMMUNICATE;
+	arg.session = pvt_data.session;
+	arg.num_params = 4;
+
+	memset(param, 0, sizeof(param));
+	param[0].attr = TEE_IOCTL_PARAM_ATTR_TYPE_MEMREF_INOUT;
+	param[0].u.memref.size = buf_size;
+	param[0].u.memref.shm = shm;
+	param[1].attr = TEE_IOCTL_PARAM_ATTR_TYPE_VALUE_OUTPUT;
+	param[2].attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
+	param[3].attr = TEE_IOCTL_PARAM_ATTR_TYPE_NONE;
+
+	rc = tee_client_invoke_func(pvt_data.ctx, &arg, param);
+	tee_shm_free(shm);
+
+	if (rc < 0 || arg.ret != 0) {
+		dev_err(pvt_data.dev,
+			"PTA_STMM_CMD_COMMUNICATE invoke error: 0x%x\n", arg.ret);
+		return EFI_DEVICE_ERROR;
+	}
+
+	switch (param[1].u.value.a) {
+	case ARM_SVC_SPM_RET_SUCCESS:
+		return EFI_SUCCESS;
+
+	case ARM_SVC_SPM_RET_INVALID_PARAMS:
+		return EFI_INVALID_PARAMETER;
+
+	case ARM_SVC_SPM_RET_DENIED:
+		return EFI_ACCESS_DENIED;
+
+	case ARM_SVC_SPM_RET_NO_MEMORY:
+		return EFI_OUT_OF_RESOURCES;
+
+	default:
+		return EFI_ACCESS_DENIED;
+	}
+}
+
+/**
+ * mm_communicate() - Adjust the communication buffer to StandAlonneMM and send
+ * it to TEE
+ *
+ * @comm_buf:		locally allocated communication buffer, buffer should
+ *			be enough big to have some headers and payload
+ * @payload_size:	payload size
+ * Return:		status code
+ */
+static efi_status_t mm_communicate(u8 *comm_buf, size_t payload_size)
+{
+	size_t dsize;
+	efi_status_t ret;
+	struct efi_mm_communicate_header *mm_hdr;
+	struct smm_variable_communicate_header *var_hdr;
+
+	dsize = payload_size + MM_COMMUNICATE_HEADER_SIZE +
+		MM_VARIABLE_COMMUNICATE_SIZE;
+	mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+	var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
+
+	ret = tee_mm_communicate(comm_buf, dsize);
+	if (ret != EFI_SUCCESS) {
+		dev_err(pvt_data.dev, "%s failed!\n", __func__);
+		return ret;
+	}
+
+	return var_hdr->ret_status;
+}
+
+/**
+ * setup_mm_hdr() -	Allocate a buffer for StandAloneMM and initialize the
+ *			header data.
+ *
+ * @dptr:		pointer address to store allocated buffer
+ * @payload_size:	payload size
+ * @func:		standAloneMM function number
+ * @ret:		EFI return code
+ * Return:		pointer to corresponding StandAloneMM function buffer or NULL
+ */
+static void *setup_mm_hdr(u8 **dptr, size_t payload_size, size_t func,
+			  efi_status_t *ret)
+{
+	const efi_guid_t mm_var_guid = EFI_MM_VARIABLE_GUID;
+	struct efi_mm_communicate_header *mm_hdr;
+	struct smm_variable_communicate_header *var_hdr;
+	u8 *comm_buf;
+
+	/* In the init function we initialize max_buffer_size with
+	 * get_max_payload(). So skip the test if max_buffer_size is initialized
+	 * StandAloneMM will perform similar checks and drop the buffer if it's
+	 * too long
+	 */
+	if (max_buffer_size &&
+	    max_buffer_size < (MM_COMMUNICATE_HEADER_SIZE +
+			       MM_VARIABLE_COMMUNICATE_SIZE + payload_size)) {
+		*ret = EFI_INVALID_PARAMETER;
+		return NULL;
+	}
+
+	comm_buf = kzalloc(MM_COMMUNICATE_HEADER_SIZE +
+				   MM_VARIABLE_COMMUNICATE_SIZE + payload_size,
+			   GFP_KERNEL);
+	if (!comm_buf) {
+		*ret = EFI_OUT_OF_RESOURCES;
+		return NULL;
+	}
+
+	mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+	memcpy(&mm_hdr->header_guid, &mm_var_guid, sizeof(mm_hdr->header_guid));
+	mm_hdr->message_len = MM_VARIABLE_COMMUNICATE_SIZE + payload_size;
+
+	var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;
+	var_hdr->function = func;
+	if (dptr)
+		*dptr = comm_buf;
+	*ret = EFI_SUCCESS;
+
+	return var_hdr->data;
+}
+
+/**
+ * get_max_payload() - Get variable payload size from StandAloneMM.
+ *
+ * @size:    size of the variable in storage
+ * Return:   status code
+ */
+static efi_status_t get_max_payload(size_t *size)
+{
+	struct smm_variable_payload_size *var_payload = NULL;
+	size_t payload_size;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	if (!size)
+		return EFI_INVALID_PARAMETER;
+
+	payload_size = sizeof(*var_payload);
+	var_payload = setup_mm_hdr(&comm_buf, payload_size,
+				   SMM_VARIABLE_FUNCTION_GET_PAYLOAD_SIZE,
+				   &ret);
+	if (!var_payload)
+		return EFI_OUT_OF_RESOURCES;
+
+	ret = mm_communicate(comm_buf, payload_size);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	/* Make sure the buffer is big enough for storing variables */
+	if (var_payload->size < MM_VARIABLE_ACCESS_HEADER_SIZE + 0x20) {
+		ret = EFI_DEVICE_ERROR;
+		goto out;
+	}
+	*size = var_payload->size;
+	/*
+	 * There seems to be a bug in EDK2 miscalculating the boundaries and
+	 * size checks, so deduct 2 more bytes to fulfill this requirement. Fix
+	 * it up here to ensure backwards compatibility with older versions
+	 * (cf. StandaloneMmPkg/Drivers/StandaloneMmCpu/AArch64/EventHandle.c.
+	 * sizeof (EFI_MM_COMMUNICATE_HEADER) instead the size minus the
+	 * flexible array member).
+	 *
+	 * size is guaranteed to be > 2 due to checks on the beginning.
+	 */
+	*size -= 2;
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static efi_status_t get_property_int(u16 *name, size_t name_size,
+				     const efi_guid_t *vendor,
+				     struct var_check_property *var_property)
+{
+	struct smm_variable_var_check_property *smm_property;
+	size_t payload_size;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	memset(var_property, 0, sizeof(*var_property));
+	payload_size = sizeof(*smm_property) + name_size;
+	if (payload_size > max_payload_size)
+		return EFI_INVALID_PARAMETER;
+
+	smm_property = setup_mm_hdr(
+		&comm_buf, payload_size,
+		SMM_VARIABLE_FUNCTION_VAR_CHECK_VARIABLE_PROPERTY_GET, &ret);
+	if (!smm_property)
+		return EFI_OUT_OF_RESOURCES;
+
+	memcpy(&smm_property->guid, vendor, sizeof(smm_property->guid));
+	smm_property->name_size = name_size;
+	memcpy(smm_property->name, 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)
+		goto out;
+	memcpy(var_property, &smm_property->property, sizeof(*var_property));
+
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static efi_status_t tee_get_variable(u16 *name, efi_guid_t *vendor,
+				     u32 *attributes, unsigned long *data_size,
+				     void *data)
+{
+	struct var_check_property var_property;
+	struct smm_variable_access *var_acc;
+	size_t payload_size;
+	size_t name_size;
+	size_t tmp_dsize;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	if (!name || !vendor || !data_size)
+		return EFI_INVALID_PARAMETER;
+
+	name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
+	if (name_size > max_payload_size - MM_VARIABLE_ACCESS_HEADER_SIZE)
+		return EFI_INVALID_PARAMETER;
+
+	/* 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;
+	}
+
+	payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + tmp_dsize;
+	var_acc = setup_mm_hdr(&comm_buf, payload_size,
+			       SMM_VARIABLE_FUNCTION_GET_VARIABLE, &ret);
+	if (!var_acc)
+		return EFI_OUT_OF_RESOURCES;
+
+	/* Fill in contents */
+	memcpy(&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;
+	memcpy(var_acc->name, name, name_size);
+
+	ret = mm_communicate(comm_buf, payload_size);
+	if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL)
+		/* Update with reported data size for trimmed case */
+		*data_size = var_acc->data_size;
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	ret = get_property_int(name, name_size, vendor, &var_property);
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	if (attributes)
+		*attributes = var_acc->attr;
+
+	if (!data) {
+		ret = EFI_INVALID_PARAMETER;
+		goto out;
+	}
+	memcpy(data, (u8 *)var_acc->name + var_acc->name_size,
+	       var_acc->data_size);
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static efi_status_t tee_get_next_variable(unsigned long *name_size,
+					  efi_char16_t *name, efi_guid_t *guid)
+{
+	struct smm_variable_getnext *var_getnext;
+	size_t payload_size;
+	size_t out_name_size;
+	size_t in_name_size;
+	u8 *comm_buf = NULL;
+	efi_status_t ret;
+
+	if (!name_size || !name || !guid)
+		return EFI_INVALID_PARAMETER;
+
+	out_name_size = *name_size;
+	in_name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
+
+	if (out_name_size < in_name_size)
+		return EFI_INVALID_PARAMETER;
+
+	if (in_name_size > max_payload_size - MM_VARIABLE_GET_NEXT_HEADER_SIZE)
+		return EFI_INVALID_PARAMETER;
+
+	/* 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;
+	var_getnext = setup_mm_hdr(&comm_buf, payload_size,
+				   SMM_VARIABLE_FUNCTION_GET_NEXT_VARIABLE_NAME,
+				   &ret);
+	if (!var_getnext)
+		return EFI_OUT_OF_RESOURCES;
+
+	/* Fill in contents */
+	memcpy(&var_getnext->guid, guid, sizeof(var_getnext->guid));
+	var_getnext->name_size = out_name_size;
+	memcpy(var_getnext->name, name, in_name_size);
+	memset((u8 *)var_getnext->name + in_name_size, 0x0,
+	       out_name_size - in_name_size);
+
+	ret = mm_communicate(comm_buf, payload_size);
+	if (ret == EFI_SUCCESS || ret == EFI_BUFFER_TOO_SMALL) {
+		/* Update with reported data size for trimmed case */
+		*name_size = var_getnext->name_size;
+	}
+	if (ret != EFI_SUCCESS)
+		goto out;
+
+	memcpy(guid, &var_getnext->guid, sizeof(*guid));
+	memcpy(name, var_getnext->name, var_getnext->name_size);
+
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static efi_status_t tee_set_variable(efi_char16_t *name, efi_guid_t *vendor,
+				     u32 attributes, unsigned long data_size,
+				     void *data)
+{
+	efi_status_t ret;
+	struct var_check_property var_property;
+	struct smm_variable_access *var_acc;
+	size_t payload_size;
+	size_t name_size;
+	u8 *comm_buf = NULL;
+
+	if (!name || name[0] == 0 || !vendor)
+		return EFI_INVALID_PARAMETER;
+
+	if (data_size > 0 && !data)
+		return EFI_INVALID_PARAMETER;
+
+	/* Check payload size */
+	name_size = (ucs2_strnlen(name, EFI_VAR_NAME_LEN) + 1) * sizeof(u16);
+	payload_size = MM_VARIABLE_ACCESS_HEADER_SIZE + name_size + data_size;
+	if (payload_size > max_payload_size)
+		return EFI_INVALID_PARAMETER;
+
+	/*
+	 * Allocate the buffer early, before switching to RW (if needed)
+	 * so we won't need to account for any failures in reading/setting
+	 * the properties, if the allocation fails
+	 */
+	var_acc = setup_mm_hdr(&comm_buf, payload_size,
+			       SMM_VARIABLE_FUNCTION_SET_VARIABLE, &ret);
+	if (!var_acc)
+		return EFI_OUT_OF_RESOURCES;
+
+	/*
+	 * The API has the ability to override RO flags. If no RO check was
+	 * requested switch the variable to RW for the duration of this call
+	 */
+	ret = get_property_int(name, name_size, vendor, &var_property);
+	if (ret != EFI_SUCCESS) {
+		dev_err(pvt_data.dev, "Getting variable property failed\n");
+		goto out;
+	}
+
+	if (var_property.property & VAR_CHECK_VARIABLE_PROPERTY_READ_ONLY) {
+		ret = EFI_WRITE_PROTECTED;
+		goto out;
+	}
+
+	/* Fill in contents */
+	memcpy(&var_acc->guid, vendor, sizeof(var_acc->guid));
+	var_acc->data_size = data_size;
+	var_acc->name_size = name_size;
+	var_acc->attr = attributes;
+	memcpy(var_acc->name, name, name_size);
+	memcpy((u8 *)var_acc->name + name_size, data, data_size);
+
+	ret = mm_communicate(comm_buf, payload_size);
+	dev_dbg(pvt_data.dev, "Set Variable %s %d %lx\n", __FILE__, __LINE__, ret);
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static efi_status_t tee_set_variable_nonblocking(efi_char16_t *name,
+						 efi_guid_t *vendor,
+						 u32 attributes,
+						 unsigned long data_size,
+						 void *data)
+{
+	return EFI_UNSUPPORTED;
+}
+
+static efi_status_t tee_query_variable_info(u32 attributes,
+					    u64 *max_variable_storage_size,
+					    u64 *remain_variable_storage_size,
+					    u64 *max_variable_size)
+{
+	struct smm_variable_query_info *mm_query_info;
+	size_t payload_size;
+	efi_status_t ret;
+	u8 *comm_buf;
+
+	payload_size = sizeof(*mm_query_info);
+	mm_query_info = setup_mm_hdr(&comm_buf, payload_size,
+				SMM_VARIABLE_FUNCTION_QUERY_VARIABLE_INFO,
+				&ret);
+	if (!mm_query_info)
+		return EFI_OUT_OF_RESOURCES;
+
+	mm_query_info->attr = attributes;
+	ret = mm_communicate(comm_buf, payload_size);
+	if (ret != EFI_SUCCESS)
+		goto out;
+	*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;
+
+out:
+	kfree(comm_buf);
+	return ret;
+}
+
+static void tee_stmm_efi_close_context(void *data)
+{
+	tee_client_close_context(pvt_data.ctx);
+}
+
+static void tee_stmm_efi_close_session(void *data)
+{
+	tee_client_close_session(pvt_data.ctx, pvt_data.session);
+}
+
+static void tee_stmm_restore_efivars_generic_ops(void)
+{
+	efivars_unregister(&tee_efivars);
+	efivars_generic_ops_register();
+}
+
+static int tee_stmm_efi_probe(struct device *dev)
+{
+	struct tee_ioctl_open_session_arg sess_arg;
+	efi_status_t ret;
+	int rc;
+
+	pvt_data.ctx = tee_client_open_context(NULL, tee_ctx_match, NULL, NULL);
+	if (IS_ERR(pvt_data.ctx))
+		return -ENODEV;
+
+	rc = devm_add_action_or_reset(dev, tee_stmm_efi_close_context, NULL);
+	if (rc)
+		return rc;
+
+	/* Open session with StMM PTA */
+	memset(&sess_arg, 0, sizeof(sess_arg));
+	export_uuid(sess_arg.uuid, &tee_stmm_efi_id_table[0].uuid);
+	rc = tee_client_open_session(pvt_data.ctx, &sess_arg, NULL);
+	if ((rc < 0) || (sess_arg.ret != 0)) {
+		dev_err(dev, "tee_client_open_session failed, err: %x\n",
+			sess_arg.ret);
+		return -EINVAL;
+	}
+	pvt_data.session = sess_arg.session;
+	pvt_data.dev = dev;
+	rc = devm_add_action_or_reset(dev, tee_stmm_efi_close_session, NULL);
+	if (rc)
+		return rc;
+
+	ret = get_max_payload(&max_payload_size);
+	if (ret != EFI_SUCCESS)
+		return -EIO;
+
+	max_buffer_size = MM_COMMUNICATE_HEADER_SIZE +
+			  MM_VARIABLE_COMMUNICATE_SIZE +
+			  max_payload_size;
+
+	tee_efivar_ops.get_variable		= tee_get_variable;
+	tee_efivar_ops.get_next_variable	= tee_get_next_variable;
+	tee_efivar_ops.set_variable		= tee_set_variable;
+	tee_efivar_ops.set_variable_nonblocking	= tee_set_variable_nonblocking;
+	tee_efivar_ops.query_variable_store	= efi_query_variable_store;
+	tee_efivar_ops.query_variable_info	= tee_query_variable_info;
+
+	efivars_generic_ops_unregister();
+	pr_info("Using TEE-based EFI runtime variable services\n");
+	efivars_register(&tee_efivars, &tee_efivar_ops);
+
+	return 0;
+}
+
+static int tee_stmm_efi_remove(struct device *dev)
+{
+	tee_stmm_restore_efivars_generic_ops();
+
+	return 0;
+}
+
+MODULE_DEVICE_TABLE(tee, tee_stmm_efi_id_table);
+
+static struct tee_client_driver tee_stmm_efi_driver = {
+	.id_table	= tee_stmm_efi_id_table,
+	.driver		= {
+		.name		= "tee-stmm-efi",
+		.bus		= &tee_bus_type,
+		.probe		= tee_stmm_efi_probe,
+		.remove		= tee_stmm_efi_remove,
+	},
+};
+
+static int __init tee_stmm_efi_mod_init(void)
+{
+	return driver_register(&tee_stmm_efi_driver.driver);
+}
+
+static void __exit tee_stmm_efi_mod_exit(void)
+{
+	driver_unregister(&tee_stmm_efi_driver.driver);
+}
+
+module_init(tee_stmm_efi_mod_init);
+module_exit(tee_stmm_efi_mod_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ilias Apalodimas <ilias.apalodimas@linaro.org>");
+MODULE_AUTHOR("Masahisa Kojima <masahisa.kojima@linaro.org>");
+MODULE_DESCRIPTION("TEE based EFI runtime variable service driver");
diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index e9dc7116daf1..f654e6f6af87 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -63,6 +63,7 @@ int efivars_register(struct efivars *efivars,
 		     const struct efivar_operations *ops)
 {
 	int rv;
+	int event;
 
 	if (down_interruptible(&efivars_lock))
 		return -EINTR;
@@ -77,6 +78,13 @@ int efivars_register(struct efivars *efivars,
 
 	__efivars = efivars;
 
+	if (efivar_supports_writes())
+		event = EFIVAR_OPS_RDWR;
+	else
+		event = EFIVAR_OPS_RDONLY;
+
+	blocking_notifier_call_chain(&efivar_ops_nh, event, NULL);
+
 	pr_info("Registered efivars operations\n");
 	rv = 0;
 out: