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

Simon Glass sjg at chromium.org
Fri Mar 10 21:50:01 CET 2023


Hi Abdellatif,

On Fri, 10 Mar 2023 at 06:11, Abdellatif El Khlifi
<abdellatif.elkhlifi at 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 at arm.com>
> Signed-off-by: Gowtham Suresh Kumar <gowtham.sureshkumar at arm.com>
> Cc: Tom Rini <trini at konsulko.com>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
> Cc: Jens Wiklander <jens.wiklander at 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 at linaro.org>
>   *  Copyright (C) 2020 Linaro Ltd. <ilias.apalodimas at linaro.org>
> + *  Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office at arm.com>
> + *    Authors:
> + *      Abdellatif El Khlifi <abdellatif.elkhlifi at 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 at linaro.org>
>   *  Copyright (C) 2019 Linaro Ltd. <ilias.apalodimas at linaro.org>
> + *  Copyright 2022-2023 Arm Limited and/or its affiliates <open-source-office at arm.com>
> + *
> + *  Authors:
> + *    Abdellatif El Khlifi <abdellatif.elkhlifi at 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


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