Re: [PATCH v6 09/10] arm_ffa: efi: introduce FF-A MM communication

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

Hi Abdellatif,

[...]

>  
>  #include <common.h>
> @@ -15,6 +17,36 @@
>  #include <malloc.h>
>  #include <mm_communication.h>
>  
> +#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
> +
> +#include <arm_ffa.h>
> +#include <cpu_func.h>
> +#include <mapmem.h>
> +
> +#ifndef FFA_SHARED_MM_BUFFER_SIZE
> +#warning "FFA_SHARED_MM_BUFFER_SIZE must be defined in include/configs/<board>.h"
> +#define FFA_SHARED_MM_BUFFER_SIZE 0
> +#endif
> +
> +#ifndef FFA_SHARED_MM_BUFFER_OFFSET
> +#warning "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
> +#warning "FFA_SHARED_MM_BUFFER_ADDR must be defined in include/configs/<board>.h"
> +#define FFA_SHARED_MM_BUFFER_ADDR 0
> +#endif

Is the device going to work with these defaults? I am assuming not, so
isn't better to treat this as compile time errors?

> +
> +/* MM return codes */
> +#define MM_SUCCESS (0)
> +
> +const char *mm_sp_svc_uuid = MM_SP_UUID;

static ?

> +
> +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 +56,7 @@ struct mm_connection {
>  	u32 session;
>  };
>  
> +#if (IS_ENABLED(CONFIG_OPTEE))
>  /**
>   * get_connection() - Retrieve OP-TEE session for a specific UUID.
>   *
> @@ -143,13 +176,224 @@ 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 ffa_notify_mm_sp(void)
> +{
> +	struct ffa_send_direct_data msg = {0};
> +	int ret;
> +	int sp_event_ret = -1;
> +
> +	if (!ffa_bus_ops_get())
> +		return -EINVAL;
> +
> +	msg.data0 = FFA_SHARED_MM_BUFFER_OFFSET; /* x3 */
> +
> +	ret = ffa_bus_ops_get()->sync_send_receive(mm_sp_id, &msg);
> +	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
> +	 */
> +
> +	return -EACCES;
> +}
>  
>  /**
> - * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
> + * 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, size = 0;
> +	int ret;
> +	struct ffa_partition_info *parts_info;
> +
> +	if (!ffa_bus_ops_get())
> +		return -EINVAL;
> +
> +	/*
> +	 * get from the driver the count of the SPs matching the UUID
> +	 */
> +	ret = ffa_bus_ops_get()->partition_info_get(mm_sp_svc_uuid, &count, NULL);
> +	if (ret != 0) {
> +		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
> +	 */
> +
> +	log_info("EFI: Pre-allocating %d partition(s) info structures\n", count);
> +
> +	parts_info = calloc(count, sizeof(struct ffa_partition_info));
> +	if (!parts_info)
> +		return -EINVAL;

-ENOMEM here is more accurate

> +
> +	size = count * sizeof(struct ffa_partition_info);
> +
> +	/*
> +	 * ask the driver to fill the
> +	 * buffer with the SPs info
> +	 */
> +	ret = ffa_bus_ops_get()->partition_info_get(mm_sp_svc_uuid, &size, parts_info);
> +	if (ret != 0) {
> +		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;
> +}
> +
> +/**
> + * 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;
> +	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 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);
> +	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();

Is this only for arm64?

> +	#endif
> +
> +	/* Announce there is data in the shared buffer */
> +
> +	ffa_ret = ffa_notify_mm_sp();
> +	if (ffa_ret)
> +		unmap_sysmem(virt_shared_buf);

This is a bit confusing handled in different places, can't we just move the
check at the end of the switch cases and remote unmap_sysmem() from case 0?

> +
> +	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) {
> +			unmap_sysmem(virt_shared_buf);
> +			return EFI_OUT_OF_RESOURCES;
> +		}
> +
> +		memcpy(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 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 mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
> @@ -162,7 +406,12 @@ 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;
>  
> -	ret = optee_mm_communicate(comm_buf, dsize);
> +	ret = ffa_bus_discover();
> +	if (ret != 0)
> +		ret = optee_mm_communicate(comm_buf, dsize);
> +	else
> +		ret = ffa_mm_communicate(comm_buf, dsize);
> +
>  	if (ret != EFI_SUCCESS) {
>  		log_err("%s failed!\n", __func__);
>  		return ret;
> @@ -258,6 +507,13 @@ 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 +953,7 @@ 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
> 

Thanks
/Ilias