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

Abdellatif El Khlifi abdellatif.elkhlifi at arm.com
Tue Nov 8 11:58:42 CET 2022


On Mon, Oct 24, 2022 at 03:30:11PM +0300, Ilias Apalodimas wrote:
> 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?

Thanks. Done in v7.

> 
> > +
> > +/* 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?

Yes, currently we only support Aarch64 which we currently need. Same done for the FF-A Linux kernel driver [1].
     
[1]: https://elixir.bootlin.com/linux/v6.1-rc3/source/drivers/firmware/arm_ffa/Kconfig#L5

> 
> > +	#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?

Done in v7.

> 
> > +
> > +	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


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