Re: [PATCH v5 09/10] arm_ffa: introduce FF-A MM communication

Abdellatif El Khlifi
2022-10-14T10:38:43Z

On Thu, Sep 29, 2022 at 12:32:42PM +0300, Ilias Apalodimas wrote:
> Hi Abdellatif,
>
> > --- a/arch/arm/cpu/armv8/cache.S
> > +++ b/arch/arm/cpu/armv8/cache.S
> > @@ -3,6 +3,9 @@
> > * (C) Copyright 2013
> > * David Feng <fenghua@phytium.com.cn>
> > *
> > + * (C) Copyright 2022 ARM Limited
> > + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> > + *
> > * This file is based on sample code from ARMv8 ARM.
> > */
> >
> > @@ -21,7 +24,11 @@
> > * x1: 0 clean & invalidate, 1 invalidate only
> > * x2~x9: clobbered
> > */
> > +#ifdef CONFIG_EFI_LOADER
> > +.pushsection .text.efi_runtime, "ax"
>
> Maybe we discussed this in the past and I forgot, but why would you need
> __asm_dcache_level, __asm_dcache_all, __asm_invalidate_dcache_alla etc in
> the runtime section ?

Because cache invalidation needs to be done at ffa_mm_communicate() level (v4 patchset).
That code is runtime compatible so all the called functions must be under .text.efi_runtime

However, since we agreed to drop EFI runtime support from the patchset, v6 patchset takes
care of that.

>
> > +#else
> > .pushsection .text.__asm_dcache_level, "ax"
> > +#endif
> > ENTRY(__asm_dcache_level)
> > lsl x12, x0, #1
> > msr csselr_el1, x12 /* select cache level */
> > @@ -65,7 +72,11 @@ ENDPROC(__asm_dcache_level)
> > *
> > * flush or invalidate all data cache by SET/WAY.
> > */
> > +#ifdef CONFIG_EFI_LOADER
> > +.pushsection .text.efi_runtime, "ax"
> > +#else
> > .pushsection .text.__asm_dcache_all, "ax"
> > +#endif
> > ENTRY(__asm_dcache_all)
> > mov x1, x0
> > dsb sy
> > @@ -109,7 +120,11 @@ ENTRY(__asm_flush_dcache_all)
> > ENDPROC(__asm_flush_dcache_all)
> > .popsection
> >
> > +#ifdef CONFIG_EFI_LOADER
> > +.pushsection .text.efi_runtime, "ax"
> > +#else
> > .pushsection .text.__asm_invalidate_dcache_all, "ax"
> > +#endif
> > ENTRY(__asm_invalidate_dcache_all)
> > mov x0, #0x1
> > b __asm_dcache_all
> > @@ -182,7 +197,11 @@ ENTRY(__asm_invalidate_icache_all)
> > ENDPROC(__asm_invalidate_icache_all)
> > .popsection
> >
> > +#ifdef CONFIG_EFI_LOADER
> > +.pushsection .text.efi_runtime, "ax"
> > +#else
> > .pushsection .text.__asm_invalidate_l3_dcache, "ax"
> > +#endif
> > WEAK(__asm_invalidate_l3_dcache)
> > mov x0, #0 /* return status as success */
> > ret
> > diff --git a/arch/arm/cpu/armv8/cache_v8.c b/arch/arm/cpu/armv8/cache_v8.c
> > index e4736e5643..45f57372c2 100644
> > --- a/arch/arm/cpu/armv8/cache_v8.c
> > +++ b/arch/arm/cpu/armv8/cache_v8.c
> > @@ -5,10 +5,14 @@
> > *
> > * (C) Copyright 2016
> > * Alexander Graf <agraf@suse.de>
> > + *
> > + * (C) Copyright 2022 ARM Limited
> > + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> > */
> >
> > #include <common.h>
> > #include <cpu_func.h>
> > +#include <efi_loader.h>
> > #include <hang.h>
> > #include <log.h>
> > #include <asm/cache.h>
> > @@ -445,7 +449,7 @@ __weak void mmu_setup(void)
> > /*
> > * Performs a invalidation of the entire data cache at all levels
> > */
> > -void invalidate_dcache_all(void)
> > +void __efi_runtime invalidate_dcache_all(void)
> > {
> > __asm_invalidate_dcache_all();
> > __asm_invalidate_l3_dcache();
> > diff --git a/include/mm_communication.h b/include/mm_communication.h
> > index e65fbde60d..fe9104c56d 100644
> > --- a/include/mm_communication.h
>
> [...]
>
> > * always begin with efi_mm_communicate_header.
> > */
> > -struct __packed efi_mm_communicate_header {
> > +struct efi_mm_communicate_header {
> > efi_guid_t header_guid;
> > size_t message_len;
> > u8 data[];
> > @@ -145,7 +150,7 @@ struct smm_variable_communicate_header {
> > * Defined in EDK2 as SMM_VARIABLE_COMMUNICATE_ACCESS_VARIABLE.
> > *
> > */
> > -struct smm_variable_access {
> > +struct __packed smm_variable_access {
>
> You are randomly adding and deleting __packed cwin both structs. But you can't do that.
> Those structs are defined in StandAloneMM. This is the reason each struct
> description has the corresponding EDK2 definition.

Thanks for the comment.

However, we are not setting randomly the __packed keyword. There is a good reason for that.
It has been explained before in this reply [1]. Basically it's because of data padding issues
breaking the communication between u-boot and secure world (Optee).

When upgrading Optee to v3.18, no issues anymore.

The __packed changes have been dropped in patchset v6.

[1]: https://lore.kernel.org/all/20220926105620.GA22382@e121910.cambridge.arm.com/

>
> > efi_guid_t guid;
> > efi_uintn_t data_size;
> > efi_uintn_t name_size;
> > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > index b8fb2701a7..d292f57244 100644
> > --- a/lib/efi_loader/Kconfig
> > +++ b/lib/efi_loader/Kconfig
> > @@ -61,13 +61,23 @@ 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
>
> I think we discussed this in the past. I don't want ifdefs in the code for
> that. FF-A is a discoverable bus. So I think what we should do here, is
> fire up the variable access driver -> probe for FF-A -> decide what to use.
>
> So it looks something like
> **************************
> **** Variable Driver *****
> **************************
> |
> |
> |
> ***************************
> ****** Discover FF-A ******
> ***************************
> | |
> | yes | No
> | |
>
> Use SP Use OP-TEE

In patchset v6, FF-A discovery is done at runtime and on demand. In our case at
the MM Variable Driver as you recommended. Thanks.

>
> > 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_boottime.c b/lib/efi_loader/efi_boottime.c
> > index d404343a7d..8a397ea21b 100644
> > --- a/lib/efi_loader/efi_boottime.c
> > +++ b/lib/efi_loader/efi_boottime.c
> > @@ -2193,6 +2193,13 @@ static efi_status_t EFIAPI efi_exit_boot_services(efi_handle_t image_handle,
> > debug("[efi_boottime][INFO]: FF-A RX/TX buffers unmapped\n");
> > #endif
> >
> > +#if CONFIG_IS_ENABLED(ARM_FFA_EFI_RUNTIME_MODE) && !CONFIG_IS_ENABLED(SANDBOX_FFA)
> > + if (ffa_copy_runtime_data())
> > + printf("ERROR: EFI: FFA: copying runtime data\n");
> > + else
> > + printf("INFO: EFI: FFA: runtime data copied\n");
> > +#endif
> > +
> > /* Patch out unsupported runtime function */
> > efi_runtime_detach();
> >
> > diff --git a/lib/efi_loader/efi_variable_tee.c b/lib/efi_loader/efi_variable_tee.c
> > index dfef18435d..d6f24f85bd 100644
> > --- a/lib/efi_loader/efi_variable_tee.c
> > +++ b/lib/efi_loader/efi_variable_tee.c
> > @@ -4,6 +4,8 @@
> > *
> > * Copyright (C) 2019 Linaro Ltd. <sughosh.ganu@linaro.org>
> > * Copyright (C) 2019 Linaro Ltd. <ilias.apalodimas@linaro.org>
> > + * Copyright (C) 2022 ARM Limited
> > + * Abdellatif El Khlifi <abdellatif.elkhlifi@arm.com>
> > */
> >
> > #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
> > +
> > +/* MM return codes */
> > +#define MM_SUCCESS (0)
> > +
> > +const char *mm_sp_svc_uuid = MM_SP_UUID;
> > +
> > +static __efi_runtime_data 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.
> > *
> > @@ -143,16 +176,227 @@ static efi_status_t optee_mm_communicate(void *comm_buf, ulong dsize)
> >
> > return ret;
> > }
> > +#endif
> > +
> > +#if (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
> >
> > /**
> > - * mm_communicate() - Adjust the cmonnucation buffer to StandAlonneMM and send
> > + * 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 __efi_runtime 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;
> > +}
> > +
> > +/**
> > + * 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;
> > +
> > + 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 __efi_runtime ffa_mm_communicate(void *comm_buf, ulong comm_buf_size)
> > +{
>
> If you are registering this as a *runtime* service you should also tweak
> the RT_PROPERTIES TABLE and enable runtime services (e.g SetVariable).
> Otherwise having as runtime makes little sense. To be honest I'd much
> prefer this whole patchset without the runtime parts. It's much easier to
> review and reason about and we can always add runtime later.

EFI runtime support removed from the FF-A work in patchset v6.

>
> > + 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);
> > + efi_memcpy_runtime(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();
> > + #endif
> > +
> > + /* Announce there is data in the shared buffer */
> > +
> > + ffa_ret = ffa_notify_mm_sp();
> > + if (ffa_ret)
> > + unmap_sysmem(virt_shared_buf);
> > +
> > + 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;
> > + }
> > +
> > + efi_memcpy_runtime(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 MM SP (also called partition) can be 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, StandAlonneMM and smm-gateway are supported.
> > + *
> > * Return: status code
> > */
> > -static efi_status_t mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
> > +static efi_status_t __efi_runtime mm_communicate(u8 *comm_buf, efi_uintn_t dsize)
>
> The optee version of the function can't be on the efi_runtime section. The
> reason is that almost the entire of the OP-TEE subsystem is not marked as
> runtime, which will lead to a crash if we ever take that path.
>
> > {
> > efi_status_t ret;
> > struct efi_mm_communicate_header *mm_hdr;
> > @@ -162,7 +406,11 @@ 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;
> >
> > + #if (IS_ENABLED(CONFIG_OPTEE))
> > ret = optee_mm_communicate(comm_buf, dsize);
> > + #elif (IS_ENABLED(CONFIG_ARM_FFA_TRANSPORT))
> > + ret = ffa_mm_communicate(comm_buf, dsize);
>
> If we enable runtime discovery of optee vs ffa, we can get rid of that and
> just pass an extra argument to mm_communicate
>
> Thanks
> /Ilias
> > + #endif
> > if (ret != EFI_SUCCESS) {
> > log_err("%s failed!\n", __func__);
> > return ret;
> > @@ -258,6 +506,13 @@ 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 +952,7 @@ 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
> >