[RFC PATCH 1/1] efi_loader: Enable RISCV_EFI_BOOT_PROTOCOL support

[Heinrich Schuchardt]

On 1/26/22 12:06, Sunil V L wrote:
> This adds support for new RISCV_EFI_BOOT_PROTOCOL to
> communicate the boot hart ID to bootloader/kernel on RISC-V
> UEFI platforms.
>
> Signed-off-by: Sunil V L <sunilvl at ventanamicro.com>
> ---
>   include/efi_api.h          |  4 +++
>   include/efi_loader.h       |  2 ++
>   include/efi_riscv.h        | 16 +++++++++
>   lib/efi_loader/Kconfig     |  7 ++++
>   lib/efi_loader/Makefile    |  1 +
>   lib/efi_loader/efi_riscv.c | 69 ++++++++++++++++++++++++++++++++++++++
>   lib/efi_loader/efi_setup.c |  6 ++++
>   7 files changed, 105 insertions(+)
>   create mode 100644 include/efi_riscv.h
>   create mode 100644 lib/efi_loader/efi_riscv.c
>
> diff --git a/include/efi_api.h b/include/efi_api.h
> index 8d5d835bd0..f123d0557c 100644
> --- a/include/efi_api.h
> +++ b/include/efi_api.h
> @@ -438,6 +438,10 @@ struct efi_runtime_services {
>   	EFI_GUID(0x607f766c, 0x7455, 0x42be, 0x93, \
>   		 0x0b, 0xe4, 0xd7, 0x6d, 0xb2, 0x72, 0x0f)
>
> +#define RISCV_EFI_BOOT_PROTOCOL_GUID \
> +	EFI_GUID(0xccd15fec, 0x6f73, 0x4eec, 0x83, \
> +		 0x95, 0x3e, 0x69, 0xe4, 0xb9, 0x40, 0xbf)
> +
>   /**
>    * struct efi_configuration_table - EFI Configuration Table
>    *
> diff --git a/include/efi_loader.h b/include/efi_loader.h
> index 701efcd2b6..1fa75b40fe 100644
> --- a/include/efi_loader.h
> +++ b/include/efi_loader.h
> @@ -527,6 +527,8 @@ efi_status_t efi_disk_register(void);
>   efi_status_t efi_rng_register(void);
>   /* Called by efi_init_obj_list() to install EFI_TCG2_PROTOCOL */
>   efi_status_t efi_tcg2_register(void);
> +/* Called by efi_init_obj_list() to install RISCV_EFI_BOOT_PROTOCOL */
> +efi_status_t efi_riscv_register(void);
>   /* Called by efi_init_obj_list() to do initial measurement */
>   efi_status_t efi_tcg2_do_initial_measurement(void);
>   /* measure the pe-coff image, extend PCR and add Event Log */
> diff --git a/include/efi_riscv.h b/include/efi_riscv.h
> new file mode 100644
> index 0000000000..6beb2637f6
> --- /dev/null
> +++ b/include/efi_riscv.h
> @@ -0,0 +1,16 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +/*
> + * RISCV_EFI_BOOT_PROTOCOL
> + *
> + * Copyright (c) 2022 Ventana Micro Systems Inc
> + */
> +
> +#include <efi_api.h>
> +
> +#define RISCV_EFI_BOOT_PROTOCOL_REVISION 0x00010000
> +

Please, add Sphinx style comments to describe the structure.

> +struct riscv_efi_boot_protocol {
> +	u64 revision;
> +	efi_status_t (EFIAPI *get_boot_hartid) (struct riscv_efi_boot_protocol *this,
> +						efi_uintn_t *boot_hartid);
> +};
> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> index 24f9a2bb75..77ba6a7ea1 100644
> --- a/lib/efi_loader/Kconfig
> +++ b/lib/efi_loader/Kconfig
> @@ -369,4 +369,11 @@ config EFI_ESRT
>   	help
>   	  Enabling this option creates the ESRT UEFI system table.
>
> +config EFI_RISCV_BOOT_PROTOCOL
> +	bool "RISCV_EFI_BOOT_PROTOCOL support"
> +	default y
> +	depends on RISCV
> +	help
> +	  Provide a RISCV_EFI_BOOT_PROTOCOL implementation on RISC-V platform.
> +
>   endif
> diff --git a/lib/efi_loader/Makefile b/lib/efi_loader/Makefile
> index fd344cea29..b2c664d108 100644
> --- a/lib/efi_loader/Makefile
> +++ b/lib/efi_loader/Makefile
> @@ -62,6 +62,7 @@ obj-$(CONFIG_GENERATE_ACPI_TABLE) += efi_acpi.o
>   obj-$(CONFIG_GENERATE_SMBIOS_TABLE) += efi_smbios.o
>   obj-$(CONFIG_EFI_RNG_PROTOCOL) += efi_rng.o
>   obj-$(CONFIG_EFI_TCG2_PROTOCOL) += efi_tcg2.o
> +obj-$(CONFIG_EFI_RISCV_BOOT_PROTOCOL) += efi_riscv.o
>   obj-$(CONFIG_EFI_LOAD_FILE2_INITRD) += efi_load_initrd.o
>   obj-$(CONFIG_EFI_SIGNATURE_SUPPORT) += efi_signature.o
>
> diff --git a/lib/efi_loader/efi_riscv.c b/lib/efi_loader/efi_riscv.c
> new file mode 100644
> index 0000000000..91b8d2b927
> --- /dev/null
> +++ b/lib/efi_loader/efi_riscv.c
> @@ -0,0 +1,69 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Defines APIs that allow an OS to interact with UEFI firmware to query
> + * information about the boot hart ID.
> + *
> + * Copyright (c) 2022, Ventana Micro Systems Inc
> + */
> +
> +#define LOG_CATEGORY LOGC_EFI
> +#include <common.h>
> +#include <efi_loader.h>
> +#include <efi_variable.h>
> +#include <log.h>
> +#include <asm/global_data.h>
> +#include <efi_riscv.h>
> +
> +DECLARE_GLOBAL_DATA_PTR;
> +
> +static const efi_guid_t efi_guid_riscv_boot_protocol = RISCV_EFI_BOOT_PROTOCOL_GUID;
> +static efi_uintn_t hartid;

I think we can do without this static variable. gd->arch.boot_hart does
not change.

> +
> +/**
> + * efi_riscv_get_boot_hartid() - return boot hart ID
> + *
> + * @this:		RISCV_EFI_BOOT_PROTOCOL instance
> + * @boot_hartid		caller allocated memory to return boot hart id
> +
> + * Return:	status code
> + */
> +static efi_status_t EFIAPI
> +efi_riscv_get_boot_hartid(struct riscv_efi_boot_protocol *this,
> +					efi_uintn_t *boot_hartid)
> +{
> +	log_err(" efi_riscv_get_boot_hartid ENTER\n");

This seems to be left from debugging.

Please, use EFI_ENTRY in all UEFI API interface implementations.

EFI_ENTRY("");

This will show the function name when enabling debug messages.

> +	if ((this == NULL) || (boot_hartid == NULL))

We try to avoid == NULL. We should check against the actual protocol.

if (this != riscv_efi_boot_prot || !boot_hartid)

> +		return EFI_INVALID_PARAMETER;
> +
> +	*boot_hartid = hartid;
> +
> +	return EFI_SUCCESS;

return EFI_EXIT(EFI_SUCCESS).

> +}
> +
> +static const struct riscv_efi_boot_protocol riscv_efi_boot_prot = {
> +	.revision = RISCV_EFI_BOOT_PROTOCOL_REVISION,
> +	.get_boot_hartid = efi_riscv_get_boot_hartid
> +};
> +
> +/**
> + * efi_riscv_register() - register RISCV_EFI_BOOT_PROTOCOL
> + *
> + *
> + * Return:	status code
> + */
> +efi_status_t efi_riscv_register(void)
> +{
> +	efi_status_t ret = EFI_SUCCESS;
> +
> +	/* save boot hart id since gd is not accessible after launching
> +	 * the kernel

gd is accessible until EXIT_BOOT_SERVICES(). After EXIT_BOOT_SERVICES
the protocol cannot be called.

set_gd(efi_gd) called by EFI_ENTRY() takes care of restoring the gp
register if the kernel should mess it up, which an UEFI program should
not do.

Best regards

Heinrich

> +	 */
> +	hartid = gd->arch.boot_hart;
> +
> +	ret = efi_add_protocol(efi_root, &efi_guid_riscv_boot_protocol,
> +			       (void *)&riscv_efi_boot_prot);
> +	if (ret != EFI_SUCCESS) {
> +		log_err("Cannot install RISCV_EFI_BOOT_PROTOCOL\n");
> +	}
> +	return ret;
> +}
> diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c
> index 49172e3579..380adc15c8 100644
> --- a/lib/efi_loader/efi_setup.c
> +++ b/lib/efi_loader/efi_setup.c
> @@ -247,6 +247,12 @@ efi_status_t efi_init_obj_list(void)
>   			goto out;
>   	}
>
> +	if (IS_ENABLED(CONFIG_EFI_RISCV_BOOT_PROTOCOL)) {
> +		ret = efi_riscv_register();
> +		if (ret != EFI_SUCCESS)
> +			goto out;
> +	}
> +
>   	/* Secure boot */
>   	ret = efi_init_secure_boot();
>   	if (ret != EFI_SUCCESS)