Re: [PATCH v9 09/10] arm_ffa: efi: introduce FF-A MM communication

Simon Glass
2023-03-10T20:56:52Z

Hi Abdellatif,

On Fri, 10 Mar 2023 at 06:11, Abdellatif El Khlifi
<abdellatif.elkhlifi@arm.com> wrote:
>
> Add MM communication support using FF-A transport
>
> This feature allows accessing MM partitions services through
> EFI MM communication protocol. MM partitions such as StandAlonneMM
> or smm-gateway secure partitions which reside in secure world.
>
> An MM shared buffer and a door bell event are used to exchange
> the 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.
>
> MM communication protocol supports FF-A 64-bit direct messaging.
>
> 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>
> Cc: Simon Glass <sjg@chromium.org>
> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org>
> Cc: Jens Wiklander <jens.wiklander@linaro.org>
>
> ---
> Changelog:
> ===============
>
> v9: align how FF-A is used with FF-A discovery through DM
>
> v8:
>
> * isolate the compilation choices between FF-A and OP-TEE
> * update partition_info_get() second argument to be an SP count
> * pass NULL device pointer to the FF-A bus discovery and operations
>
> v7:
>
> * set the MM door bell event to use 64-bit direct messaging
> * issue a compile time error when one of these macros are not found :
> FFA_SHARED_MM_BUFFER_SIZE, FFA_SHARED_MM_BUFFER_OFFSET, FFA_SHARED_MM_BUFFER_ADDR
> * make mm_sp_svc_uuid static
> * replace EINVAL with ENOMEM in ffa_discover_mm_sp_id() when calloc() fails
> * improve use of unmap_sysmem() in ffa_mm_communicate()
>
> v6:
>
> * add FF-A runtime discovery at MM communication level
> * drop EFI runtime support for FF-A MM communication
> * revert the changes in include/mm_communication.h for
> efi_mm_communicate_header and smm_variable_access structures
>
> v4:
>
> * use the new FF-A driver interfaces
> * discover MM partitions at runtime
> * copy FF-A driver private data to EFI runtime section at
> ExitBootServices()
> * drop use of FFA_ERR_STAT_SUCCESS error code
> * replace EFI_BUFFER_TOO_SMALL with EFI_OUT_OF_RESOURCES
> in ffa_mm_communicate(). No need for efi_memcpy_runtime() anymore
> * revert the error log in mm_communicate() in case of failure
> * remove packed attribute from efi_mm_communicate_header and
> smm_variable_communicate_header
>
> v2:
>
> * set default values to 0 for FFA_SHARED_MM_BUFFER_SIZE, FFA_SHARED_MM_BUFFER_ADDR and MM_SP_UUID_DATA and add warnings
>
> v1:
>
> * introduce FF-A MM communication
>
> include/mm_communication.h | 6 +
> lib/efi_loader/Kconfig | 14 +-
> lib/efi_loader/efi_variable_tee.c | 317 +++++++++++++++++++++++++++++-
> 3 files changed, 331 insertions(+), 6 deletions(-)
>
> diff --git a/include/mm_communication.h b/include/mm_communication.h
> index e65fbde60d..87509fec3f 100644
> --- a/include/mm_communication.h
> +++ b/include/mm_communication.h
> @@ -6,6 +6,9 @@
> * Copyright (c) 2017, Intel Corporation. All rights reserved.
> * Copyright (C) 2020 Linaro Ltd. <sughosh.ganu@linaro.org>
> * Copyright (C) 2020 Linaro Ltd. <ilias.apalodimas@linaro.org>
> + * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
> + * Authors:
> + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> */
>
> #ifndef _MM_COMMUNICATION_H_
> @@ -13,6 +16,9 @@
>
> #include <part_efi.h>
>
> +/* MM service UUID string (big-endian format). This UUID is common across all MM SPs */
> +#define MM_SP_UUID "33d532ed-e699-0942-c09c-a798d9cd722d"
> +
> /*
> * Interface to the pseudo Trusted Application (TA), which provides a
> * communication channel with the Standalone MM (Management Mode)
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index c5835e6ef6..08a6b84101 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
> + Allowing access to the MM SP services (SPs such as StandAlonneMM, smm-gateway).
> + When using the u-boot OP-TEE driver, StandAlonneMM is supported.
> + When using the u-boot FF-A driver any MM SP is 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 in the secure 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.
> +
> config EFI_VARIABLE_NO_STORE
> bool "Don't persist non-volatile UEFI variables"
> help
> diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
> index dfef18435d..86207f1ff2 100644
> --- a/lib/efi_loader/efi_variable_tee.c
> +++ b/lib/efi_loader/efi_variable_tee.c
> @@ -4,9 +4,14 @@
> *
> * Copyright (C) 2019 Linaro Ltd. <sughosh.ganu@linaro.org>
> * Copyright (C) 2019 Linaro Ltd. <ilias.apalodimas@linaro.org>
> + * Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office@arm.com>
> + *
> + * Authors:
> + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> */
>
> #include <common.h>
> +#include <dm.h>
> #include <efi.h>
> #include <efi_api.h>
> #include <efi_loader.h>
> @@ -15,6 +20,36 @@
> #include <malloc.h>
> #include <mm_communication.h>
>
> +#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))

Please avoid excluding code unless you need to

> +
> +#include <arm_ffa.h>
> +#include <cpu_func.h>
> +#include <mapmem.h>
> +
> +#ifndef FFA_SHARED_MM_BUFFER_SIZE
> +#error "FFA_SHARED_MM_BUFFER_SIZE must be defined in include/configs/<board>.h"
> +#define FFA_SHARED_MM_BUFFER_SIZE 0

Shouldn't that info be in the DT?

> +#endif
> +
> +#ifndef FFA_SHARED_MM_BUFFER_OFFSET
> +#error "FFA_SHARED_MM_BUFFER_OFFSET must be defined in include/configs/<board>.h"
> +#define FFA_SHARED_MM_BUFFER_OFFSET 0
> +#endif
> +
> +#ifndef FFA_SHARED_MM_BUFFER_ADDR
> +#error "FFA_SHARED_MM_BUFFER_ADDR must be defined in include/configs/<board>.h"
> +#define FFA_SHARED_MM_BUFFER_ADDR 0
> +#endif
> +
> +/* MM return codes */
> +#define MM_SUCCESS (0)
> +
> +static const char *mm_sp_svc_uuid = MM_SP_UUID;
> +
> +static 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 +59,7 @@ struct mm_connection {
> u32 session;
> };
>
> +#if (IS_ENABLED(CONFIG_OPTEE))

same here

> /**
> * get_connection() - Retrieve OP-TEE session for a specific UUID.
> *
> @@ -143,13 +179,269 @@ static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)
>
> return ret;
> }
> +#endif
> +
> +#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))

and here

> +
> +/**
> + * 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 ffa_notify_mm_sp(void)
> +{
> + struct ffa_send_direct_data msg = {0};
> + int ret;
> + int sp_event_ret = -1;
> + struct udevice *ffa_dev = NULL;
> + struct ffa_bus_ops *ffa_ops = NULL;
> +
> + uclass_get_device_by_name(UCLASS_FFA, "arm_ffa", &ffa_dev);

uclass_first_device()

> + if (!ffa_dev) {
> + log_err("EFI: Cannot find FF-A bus device, notify MM SP failure\n");
> + return -ENODEV;
> + }
> +
> + ffa_ops = (struct ffa_bus_ops *)ffa_bus_get_ops(ffa_dev);
> + if (!ffa_ops) {
> + log_err("EFI: Invalid FF-A ops, notify MM SP failure\n");
> + return -EINVAL;
> + }
> +
> + msg.data0 = FFA_SHARED_MM_BUFFER_OFFSET; /* x3 */
> +
> + ret = ffa_ops->sync_send_receive(ffa_dev, mm_sp_id, &msg, 1);
> + if (ret != 0)
> + return ret;
> +
> + sp_event_ret = msg.data0; /* x3 */
> +
> + if (sp_event_ret == MM_SUCCESS)
> + return 0;
> +
> + /*
> + * Failure to notify the MM SP
> + */

/* Failure ... */

> +
> + 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)
> +{
> + u32 count = 0;
> + int ret;
> + struct ffa_partition_info *parts_info;
> + struct udevice *ffa_dev = NULL;
> + struct ffa_bus_ops *ffa_ops = NULL;
> +
> + uclass_get_device_by_name(UCLASS_FFA, "arm_ffa", &ffa_dev);
> + if (!ffa_dev) {
> + log_err("EFI: Cannot find FF-A bus device, MM SP discovery failure\n");
> + return -ENODEV;
> + }
> +
> + ffa_ops = (struct ffa_bus_ops *)ffa_bus_get_ops(ffa_dev);
> + if (!ffa_ops) {
> + log_err("EFI: Invalid FF-A ops, MM SP discovery failure\n");
> + return -EINVAL;
> + }
> +
> + /* Get from the driver the count of the SPs matching the UUID */
> + ret = ffa_ops->partition_info_get(ffa_dev, mm_sp_svc_uuid, &count, NULL);
> + if (ret != 0) {
> + log_err("EFI: Failure in querying SPs count (%d), MM SP discovery failure\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 */
> +
> + log_info("EFI: Pre-allocating %d partition(s) info structures\n", count);
> +
> + parts_info = calloc(count, sizeof(*parts_info));
> + if (!parts_info)
> + return -ENOMEM;
> +
> + /* Ask the driver to fill the buffer with the SPs info */
> + ret = ffa_ops->partition_info_get(ffa_dev, mm_sp_svc_uuid, &count, parts_info);
> + if (ret) {
> + log_err("EFI: Failure in querying SPs info (%d), MM SP discovery failure\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;
> +}
> +
> +/**
> + * 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 ffa_mm_communicate(void *comm_buf, ulong comm_buf_size)
> +{
> + ulong tx_data_size;
> + int ffa_ret;
> + efi_status_t efi_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() != 0) {
> + log_err("EFI: Failure to discover MM SP ID at boot time, FF-A MM comms failure\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 = map_sysmem((phys_addr_t)FFA_SHARED_MM_BUFFER_ADDR, 0);
> + memcpy(virt_shared_buf, comm_buf, tx_data_size);
> +
> + /*
> + * The secure world might have cache disabled for
> + * the device region used for shared buffer (which is the case for Optee).
> + * In this case, 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();

indent, I think?

> + #endif
> +
> + /* Announce there is data in the shared buffer */
> +
> + ffa_ret = ffa_notify_mm_sp();
> +
> + switch (ffa_ret) {
> + case 0:
> + {

Don't we normally put the { at the end of the previous line?

> + 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_ret = EFI_OUT_OF_RESOURCES;
> + break;
> + }
> +
> + memcpy(comm_buf, virt_shared_buf, rx_data_size);
> + efi_ret = EFI_SUCCESS;
> + break;
> + }
> + case -EINVAL:
> + efi_ret = EFI_DEVICE_ERROR;
> + break;
> + case -EPERM:
> + efi_ret = EFI_INVALID_PARAMETER;
> + break;
> + case -EACCES:
> + efi_ret = EFI_ACCESS_DENIED;
> + break;
> + case -EBUSY:
> + efi_ret = EFI_OUT_OF_RESOURCES;
> + break;
> + default:
> + efi_ret = EFI_ACCESS_DENIED;
> + }
> +
> + unmap_sysmem(virt_shared_buf);
> + return efi_ret;
> +}
> +#endif
> +
> +/**
> + * select_ffa_mm_comms() - checks FF-A support availability
> + *
> + * Making sure FF-A is compiled in. If that's the case try to make sure
> + * the FF-A bus is probed successfully which means FF-A communication
> + * with secure world works and ready to be used.
> + *
> + * Return:
> + *
> + * 0: FF-A ready for use. Otherwise, failure
> + */
> +static efi_status_t select_ffa_mm_comms(void)
> +{
> + efi_status_t ret = EFI_UNSUPPORTED;
> +
> + if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT)) {
> + struct udevice *dev = NULL;
> +
> + uclass_get_device_by_name(UCLASS_FFA, "arm_ffa", &dev);
> + if (!dev) {
> + log_err("EFI: Cannot find FF-A bus device, cannot select FF-A comms\n");
> + ret = EFI_NOT_READY;
> + } else {
> + ret = EFI_SUCCESS;
> + }
> + }
> +
> + return ret;
> +}
>
> /**
> - * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
speeding

> + * mm_communicate() - Adjust the communication buffer to the MM SP and send
> * it to OP-TEE
> *
> - * @comm_buf: locally allocted communcation buffer

spelling

> + * @comm_buf: locally allocated communication buffer
> * @dsize: buffer size
> + *
> + * The SP (also called partition) can be any MM SP such as 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, any MM SP is supported.
> + *
> * Return: status code
> */
> static efi_status_t (u8 *comm_buf, efi_uintn_t dsize)
> @@ -162,7 +454,17 @@ 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;

smm_var_comms_hdr would be a lot shorter!

>
> - ret = optee_mm_communicate(comm_buf, dsize);
> + ret = select_ffa_mm_comms();
> + if (ret != EFI_SUCCESS) {
> +#if (IS_ENABLED(CONFIG_OPTEE))
> + ret = optee_mm_communicate(comm_buf, dsize);
> +#endif
> + } else {
> +#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
> + ret = ffa_mm_communicate(comm_buf, dsize);
> +#endif
> + }
> +
> if (ret != EFI_SUCCESS) {
> log_err("%s failed!\n", __func__);
> return ret;
> @@ -258,6 +560,13 @@ 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 +1006,7 @@ 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);
>
> /*
> --
> 2.25.1
>

Regards,
Simonn