[PATCH 6/6] arm_ffa: introduce FF-A MM communication

abdellatif.elkhlifi
2022-03-29T16:15:49Z

From: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>

Add MM communication support using FF-A transport

FF-A MM communication allows exchanging data with StandAlonneMM
or smm-gateway secure partitions which run in OP-TEE.

An MM shared buffer and a door bell event are used to exchange
this data.

The data is used by EFI services such as GetVariable()/SetVariable()
and copied from the communication buffer to the MM shared buffer.

The secure partition is notified about availability of data in the
MM shared buffer by an FF-A message (door bell).

On such event, MM SP can read the data and updates the MM shared
buffer with the response data.

The response data is copied back to the communication buffer and
consumed by the EFI subsystem.

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
Signed-off-by: Gowtham Suresh Kumar <gowtham.sureshkumar@arm.com>
Cc: Tom Rini <trini@konsulko.com>
---
arch/arm/cpu/armv8/cache.S | 16 ++
arch/arm/cpu/armv8/cache_v8.c | 3 +-
include/mm_communication.h | 4 +-
lib/efi_loader/Kconfig | 14 +-
lib/efi_loader/efi_variable_tee.c | 294 +++++++++++++++++++++++++++++-
5 files changed, 321 insertions(+), 10 deletions(-)

diff --git a/arch/arm/cpu/armv8/cache.S b/arch/arm/cpu/armv8/cache.S
index d1cee23437..bdbe89e0c5 100644
--- a/arch/arm/cpu/armv8/cache.S
+++ b/arch/arm/cpu/armv8/cache.S
@@ -21,7 +21,11 @@
* x1: 0 clean & invalidate, 1 invalidate only
* x2~x9: clobbered
*/
+#ifdef CONFIG_ARM_FFA_TRANSPORT
+.pushsection .text.efi_runtime, "ax"
+#else
.pushsection .text.__asm_dcache_level, "ax"
+#endif
ENTRY(__asm_dcache_level)
lsl x12, x0, #1
msr csselr_el1, x12 /* select cache level */
@@ -65,7 +69,11 @@ ENDPROC(__asm_dcache_level)
*
* flush or invalidate all data cache by SET/WAY.
*/
+#ifdef CONFIG_ARM_FFA_TRANSPORT
+.pushsection .text.efi_runtime, "ax"
+#else
.pushsection .text.__asm_dcache_all, "ax"
+#endif
ENTRY(__asm_dcache_all)
mov x1, x0
dsb sy
@@ -109,7 +117,11 @@ ENTRY(__asm_flush_dcache_all)
ENDPROC(__asm_flush_dcache_all)
.popsection

+#ifdef CONFIG_ARM_FFA_TRANSPORT
+.pushsection .text.efi_runtime, "ax"
+#else
.pushsection .text.__asm_invalidate_dcache_all, "ax"
+#endif
ENTRY(__asm_invalidate_dcache_all)
mov x0, #0x1
b __asm_dcache_all
@@ -182,7 +194,11 @@ ENTRY(__asm_invalidate_icache_all)
ENDPROC(__asm_invalidate_icache_all)
.popsection

+#ifdef CONFIG_ARM_FFA_TRANSPORT
+.pushsection .text.efi_runtime, "ax"
+#else
.pushsection .text.__asm_invalidate_l3_dcache, "ax"
+#endif
WEAK(__asm_invalidate_l3_dcache)
mov x0, #0 /* return status as success */
ret
diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
index 3de18c7675..187a4497a7 100644
--- a/arch/arm/cpu/armv8/cache_v8.c
+++ b/arch/arm/cpu/armv8/cache_v8.c
@@ -9,6 +9,7 @@

#include <common.h>
#include <cpu_func.h>
+#include <efi_loader.h>
#include <hang.h>
#include <log.h>
#include <asm/cache.h>
@@ -425,7 +426,7 @@ __weak void mmu_setup(void)
/*
* Performs a invalidation of the entire data cache at all levels
*/
-void invalidate_dcache_all(void)
+void __efi_runtime invalidate_dcache_all(void)
{
__asm_invalidate_dcache_all();
__asm_invalidate_l3_dcache();
diff --git a/include/mm_communication.h b/include/mm_communication.h
index e65fbde60d..bb99190956 100644
--- a/include/mm_communication.h
+++ b/include/mm_communication.h
@@ -123,7 +123,7 @@ struct __packed efi_mm_communicate_header {
*
* Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_HEADER.
*/
-struct smm_variable_communicate_header {
+struct __packed smm_variable_communicate_header {
efi_uintn_t function;
efi_status_t ret_status;
u8 data[];
@@ -145,7 +145,7 @@ struct smm_variable_communicate_header {
* Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE.
*
*/
-struct smm_variable_access {
+struct __packed smm_variable_access {
efi_guid_t guid;
efi_uintn_t data_size;
efi_uintn_t name_size;
diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
index 28657f50c9..0d69133595 100644
--- a/lib/efi_loader/Kconfig
+++ b/lib/efi_loader/Kconfig
@@ -55,13 +55,23 @@ config EFI_VARIABLE_FILE_STORE
stored as file /ubootefi.var on the EFI system partition.

config EFI_MM_COMM_TEE
- bool "UEFI variables storage service via OP-TEE"
- depends on OPTEE
+ bool "UEFI variables storage service via the trusted world"
+ depends on OPTEE || ARM_FFA_TRANSPORT
help
+ The MM SP (also called partition) can be StandAlonneMM or smm-gateway.
+ When using the u-boot OP-TEE driver, StandAlonneMM is supported.
+ When using the u-boot FF-A driver, StandAlonneMM and smm-gateway are supported.
+
If OP-TEE is present and running StandAloneMM, dispatch all UEFI
variable related operations to that. The application will verify,
authenticate and store the variables on an RPMB.

+ When ARM_FFA_TRANSPORT is used, dispatch all UEFI variable related
+ operations to the MM SP running under Optee in the trusted world.
+ A door bell mechanism is used to notify the SP when there is data in the shared
+ MM buffer. The data is copied by u-boot to the shared buffer before issuing
+ the door bell event.
+
endchoice

config EFI_VARIABLES_PRESEED
diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
index dfef18435d..3d01985662 100644
--- a/lib/efi_loader/efi_variable_tee.c
+++ b/lib/efi_loader/efi_variable_tee.c
@@ -15,6 +15,53 @@
#include <malloc.h>
#include <mm_communication.h>

+#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
+
+#include <arm_ffa_helper.h>
+#include <cpu_func.h>
+#include <mapmem.h>
+
+#ifndef FFA_SHARED_MM_BUFFER_SIZE
+
+#include <linux/sizes.h>
+#define FFA_SHARED_MM_BUFFER_SIZE SZ_4K /* 4 KB */
+
+#endif
+
+#ifndef FFA_SHARED_MM_BUFFER_ADDR
+
+/*
+ * shared buffer physical address used for communication between
+ * u-boot and the MM SP
+ */
+#define FFA_SHARED_MM_BUFFER_ADDR (0x023F8000)
+
+#endif
+
+/* MM return codes */
+#define MM_SUCCESS (0)
+
+#define ARM_SVC_ID_SP_EVENT_COMPLETE_AARCH64 (0xC4000061)
+#define ARM_SVC_ID_SP_EVENT_COMPLETE ARM_SVC_ID_SP_EVENT_COMPLETE_AARCH64
+
+#ifndef MM_SP_UUID_DATA
+
+/* MM SP UUID binary data (little-endian format) */
+#define MM_SP_UUID_DATA \
+ 0xed, 0x32, 0xd5, 0x33, \
+ 0x99, 0xe6, 0x42, 0x09, \
+ 0x9c, 0xc0, 0x2d, 0x72, \
+ 0xcd, 0xd9, 0x98, 0xa7
+
+#endif
+
+/* MM_SP_UUID_DATA defined by the platform */
+union ffa_partition_uuid mm_sp_svc_uuid = {.bytes = {MM_SP_UUID_DATA}};
+
+static __efi_runtime_data u16 mm_sp_id;
+
+#endif
+
extern struct efi_var_file __efi_runtime_data *efi_var_buf;
static efi_uintn_t max_buffer_size; /* comm + var + func + data */
static efi_uintn_t max_payload_size; /* func + data */
@@ -24,6 +71,7 @@ struct mm_connection {
u32 session;
};

+#if (IS_ENABLED(CONFIG_OPTEE))
/**
* get_connection() - Retrieve OP-TEE session for a specific UUID.
*
@@ -143,16 +191,238 @@ static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)

return ret;
}
+#endif
+
+#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
+
+/**
+ * ffa_notify_mm_sp() - Announce there is data in the shared buffer
+ *
+ * Notifies the MM partition in the trusted world that
+ * data is available in the shared buffer.
+ * This is a blocking call during which trusted world has exclusive access
+ * to the MM shared buffer.
+ *
+ * Return:
+ *
+ * 0 on success
+ */
+static int __efi_runtime ffa_notify_mm_sp(void)
+{
+ struct ffa_interface_data func_data = {0};
+ struct ffa_send_direct_data msg = {0};
+ int ret;
+ u32 sp_event_complete;
+ int sp_event_ret;
+
+ func_data.data0_size = sizeof(mm_sp_id);
+ func_data.data0 = &mm_sp_id;
+
+ msg.a3 = FFA_SHARED_MM_BUFFER_ADDR;
+ msg.a4 = FFA_SHARED_MM_BUFFER_SIZE;
+ func_data.data1_size = sizeof(msg);
+ func_data.data1 = &msg;
+
+ ret = ffa_helper_msg_send_direct_req(&func_data);
+ if (ret != FFA_ERR_STAT_SUCCESS)
+ return ret;
+
+ sp_event_complete = msg.a3;
+ sp_event_ret = (int)msg.a4;
+
+ if (sp_event_complete == ARM_SVC_ID_SP_EVENT_COMPLETE && sp_event_ret == MM_SUCCESS)
+ return 0;
+
+ /*
+ * Failure to notify the MM SP
+ */
+
+ return -EACCES;
+}
+
+/**
+ * ffa_discover_mm_sp_id() - Query the MM partition ID
+ *
+ * Use the FF-A driver to get the MM partition ID.
+ * If multiple partitions are found, use the first one.
+ * This is a boot time function.
+ *
+ * Return:
+ *
+ * 0 on success
+ */
+static int ffa_discover_mm_sp_id(void)
+{
+ struct ffa_interface_data func_data = {0};
+ u32 count = 0;
+ int ret;
+ struct ffa_partition_info *parts_info;
+
+ /*
+ * get from the driver the count of the SPs matching the UUID
+ */
+ func_data.data0_size = sizeof(mm_sp_svc_uuid);
+ func_data.data0 = &mm_sp_svc_uuid;
+ func_data.data1_size = sizeof(count);
+ func_data.data1 = &count;
+
+ ret = ffa_helper_get_partitions_info(&func_data);
+ if (ret != FFA_ERR_STAT_SUCCESS) {
+ log_err("EFI: Failure in querying partitions count (error code: %d)\n", ret);
+ return ret;
+ }
+
+ if (!count) {
+ log_info("EFI: No MM partition found\n");
+ return ret;
+ }
+
+ /*
+ * pre-allocate a buffer to be filled by the driver
+ * with ffa_partition_info structs
+ */
+
+ parts_info = calloc(count, sizeof(struct ffa_partition_info));
+ if (!parts_info)
+ return -EINVAL;
+
+ log_info("EFI: Pre-allocating %d partition(s) info structures\n", count);
+
+ func_data.data1_size = count *
+ sizeof(struct ffa_partition_info);
+ func_data.data1 = parts_info;
+
+ /*
+ * ask the driver to fill the
+ * buffer with the SPs info
+ */
+ ret = ffa_helper_get_partitions_info(&func_data);
+ if (ret != FFA_ERR_STAT_SUCCESS) {
+ log_err("EFI: Failure in querying partition(s) info (error code: %d)\n", ret);
+ free(parts_info);
+ return ret;
+ }
+
+ /*
+ * MM SPs found , use the first one
+ */
+
+ mm_sp_id = parts_info[0].id;
+
+ log_info("EFI: MM partition ID 0x%x\n", mm_sp_id);
+
+ free(parts_info);
+
+ return 0;
+}

/**
- * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
+ * ffa_mm_communicate() - Exchange EFI services data with the MM partition using FF-A
+ * @comm_buf: locally allocated communication buffer used for rx/tx
+ * @dsize: communication buffer size
+ *
+ * Issues a door bell event to notify the MM partition (SP) running in OP-TEE
+ * that there is data to read from the shared buffer.
+ * Communication with the MM SP is performed using FF-A transport.
+ * On the event, MM SP can read the data from the buffer and
+ * update the MM shared buffer with response data.
+ * The response data is copied back to the communication buffer.
+ *
+ * Return:
+ *
+ * EFI status code
+ */
+static efi_status_t __efi_runtime ffa_mm_communicate(void *comm_buf, ulong comm_buf_size)
+{
+ ulong tx_data_size;
+ int ffa_ret;
+ struct efi_mm_communicate_header *mm_hdr;
+ void *virt_shared_buf;
+
+ if (!comm_buf)
+ return EFI_INVALID_PARAMETER;
+
+ /* Discover MM partition ID at boot time */
+ if (!mm_sp_id && ffa_discover_mm_sp_id() != FFA_ERR_STAT_SUCCESS) {
+ log_err("EFI: Failure to discover MM partition ID at boot time\n");
+ return EFI_UNSUPPORTED;
+ }
+
+ mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
+ tx_data_size = mm_hdr->message_len + sizeof(efi_guid_t) + sizeof(size_t);
+
+ if (comm_buf_size != tx_data_size || tx_data_size > FFA_SHARED_MM_BUFFER_SIZE)
+ return EFI_INVALID_PARAMETER;
+
+ /* Copy the data to the shared buffer */
+
+ virt_shared_buf = (void *)map_sysmem((phys_addr_t)FFA_SHARED_MM_BUFFER_ADDR, 0);
+ efi_memcpy_runtime(virt_shared_buf, comm_buf, tx_data_size);
+
+ /*
+ * The secure world has cache disabled for device region which we use for shared buffer.
+ * So, the secure world reads the data from DRAM. Let's flush the cache so the DRAM is
+ * updated with the latest data.
+ */
+ #ifdef CONFIG_ARM64
+ invalidate_dcache_all();
+ #endif
+
+ /* Announce there is data in the shared buffer */
+
+ ffa_ret = ffa_notify_mm_sp();
+ if (ffa_ret)
+ unmap_sysmem(virt_shared_buf);
+
+ switch (ffa_ret) {
+ case 0:
+ {
+ ulong rx_data_size;
+ /* Copy the MM SP response from the shared buffer to the communication buffer */
+ rx_data_size = ((struct efi_mm_communicate_header *)virt_shared_buf)->message_len +
+ sizeof(efi_guid_t) +
+ sizeof(size_t);
+
+ if (rx_data_size > comm_buf_size) {
+ efi_memcpy_runtime(comm_buf, virt_shared_buf, comm_buf_size);
+ unmap_sysmem(virt_shared_buf);
+ return EFI_BUFFER_TOO_SMALL;
+ }
+
+ efi_memcpy_runtime(comm_buf, virt_shared_buf, rx_data_size);
+ unmap_sysmem(virt_shared_buf);
+
+ return EFI_SUCCESS;
+ }
+ case -EINVAL:
+ return EFI_DEVICE_ERROR;
+ case -EPERM:
+ return EFI_INVALID_PARAMETER;
+ case -EACCES:
+ return EFI_ACCESS_DENIED;
+ case -EBUSY:
+ return EFI_OUT_OF_RESOURCES;
+ default:
+ return EFI_ACCESS_DENIED;
+ }
+}
+#endif
+
+/**
+ * mm_communicate() - Adjust the communication buffer to the MM SP and send
* it to OP-TEE
*
- * @comm_buf: locally allocted communcation buffer
+ * @comm_buf: locally allocated communication buffer
* @dsize: buffer size
+ *
+ * The MM SP (also called partition) can be StandAlonneMM or smm-gateway.
+ * The comm_buf format is the same for both partitions.
+ * When using the u-boot OP-TEE driver, StandAlonneMM is supported.
+ * When using the u-boot FF-A driver, StandAlonneMM and smm-gateway are supported.
+ *
* Return: status code
*/
-static efi_status_t mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
+static efi_status_t __efi_runtime mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
{
efi_status_t ret;
struct efi_mm_communicate_header *mm_hdr;
@@ -162,9 +432,16 @@ static efi_status_t mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
mm_hdr = (struct efi_mm_communicate_header *)comm_buf;
var_hdr = (struct smm_variable_communicate_header *)mm_hdr->data;

+ #if (IS_ENABLED(CONFIG_OPTEE))
ret = optee_mm_communicate(comm_buf, dsize);
+ #elif (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
+ ret = ffa_mm_communicate(comm_buf, dsize);
+ #endif
if (ret != EFI_SUCCESS) {
- log_err("%s failed!\n", __func__);
+ /* No need for showing a log here. mm_communicate failure happens
+ * when getVariable() is called with data size set to 0.
+ * This is not expected so no log shown.
+ */
return ret;
}

@@ -258,6 +535,13 @@ efi_status_t EFIAPI get_max_payload(efi_uintn_t *size)
goto out;
}
*size = var_payload->size;
+
+ #if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
+ if (*size > FFA_SHARED_MM_BUFFER_SIZE)
+ *size = FFA_SHARED_MM_BUFFER_SIZE - MM_COMMUNICATE_HEADER_SIZE -
+ MM_VARIABLE_COMMUNICATE_SIZE;
+ #endif
+
/*
* There seems to be a bug in EDK2 miscalculating the boundaries and
* size checks, so deduct 2 more bytes to fulfill this requirement. Fix
@@ -697,7 +981,7 @@ void efi_variables_boot_exit_notify(void)
ret = EFI_NOT_FOUND;

if (ret != EFI_SUCCESS)
- log_err("Unable to notify StMM for ExitBootServices\n");
+ log_err("Unable to notify the MM partition for ExitBootServices\n");
free(comm_buf);

/*
--
2.17.1