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

Abdellatif El Khlifi
2022-11-08T10:58:54Z

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