linux-kernel - Re: [RFC PATCH 1/1] riscv/efi_stub: Add support for RISCV_EFI_BOOT

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Message-ID: <CAMj1kXGaBJX9qVXQXiFHPySfDz7SWYQ6+cbHvV5v3sw3tEv0Ow@mail.gmail.com>
Date:   Wed, 26 Jan 2022 12:13:42 +0100
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Sunil V L <sunilvl@...tanamicro.com>
Cc:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-riscv <linux-riscv@...ts.infradead.org>,
        Heinrich Schuchardt <xypron.glpk@....de>,
        Anup Patel <apatel@...tanamicro.com>,
        Atish Patra <atishp@...osinc.com>,
        Abner Chang <abner.chang@....com>,
        Jessica Clarke <jrtc27@...c27.com>
Subject: Re: [RFC PATCH 1/1] riscv/efi_stub: Add support for RISCV_EFI_BOOT_PROTOCOL

Hello Sunil,

On Wed, 26 Jan 2022 at 12:06, Sunil V L <sunilvl@...tanamicro.com> wrote:
>
> This patch adds the support for getting the boot hart ID in
> Linux EFI stub using RISCV_EFI_BOOT_PROTOCOL.
>
> Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
> ---
>  drivers/firmware/efi/libstub/efistub.h    | 15 ++++++++++++
>  drivers/firmware/efi/libstub/riscv-stub.c | 28 ++++++++++++++++++++---
>  include/linux/efi.h                       |  1 +
>  3 files changed, 41 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index edb77b0621ea..0428f8816942 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -720,6 +720,21 @@ union efi_tcg2_protocol {
>         } mixed_mode;
>  };
>
> +typedef union riscv_efi_boot_protocol riscv_efi_boot_protocol_t;
> +
> +union riscv_efi_boot_protocol {
> +       struct {
> +               u64 revision;
> +               efi_status_t (__efiapi *get_boot_hartid)(
> +                                                        riscv_efi_boot_protocol_t *,
> +                                                        size_t *);
> +       };
> +       struct {
> +               u32 revision;
> +               u32 get_boot_hartid;
> +       } mixed_mode;
> +};
> +

You don't the mixed mode member here - this is for X64 kernels on IA32
firmware only.

>  typedef union efi_load_file_protocol efi_load_file_protocol_t;
>  typedef union efi_load_file_protocol efi_load_file2_protocol_t;
>
> diff --git a/drivers/firmware/efi/libstub/riscv-stub.c b/drivers/firmware/efi/libstub/riscv-stub.c
> index 380e4e251399..c7add4eb5453 100644
> --- a/drivers/firmware/efi/libstub/riscv-stub.c
> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
> @@ -46,12 +46,34 @@ static u32 get_boot_hartid_from_fdt(void)
>         return fdt32_to_cpu(*prop);
>  }
>
> +static u32 get_boot_hartid_from_efi(void)
> +{
> +       efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
> +       efi_status_t status;
> +       riscv_efi_boot_protocol_t *boot_protocol;
> +       size_t boot_hart_id;
> +
> +       status = efi_bs_call(locate_protocol, &boot_protocol_guid, NULL,
> +                            (void **)&boot_protocol);
> +       if (status == EFI_SUCCESS) {
> +               status = efi_call_proto(boot_protocol,
> +                                       get_boot_hartid, &boot_hart_id);
> +               if (status == EFI_SUCCESS) {
> +                       return (u32)boot_hart_id;
> +               }
> +       }
> +       return U32_MAX;
> +}
> +
>  efi_status_t check_platform_features(void)
>  {
> -       hartid = get_boot_hartid_from_fdt();
> +       hartid = get_boot_hartid_from_efi();
>         if (hartid == U32_MAX) {
> -               efi_err("/chosen/boot-hartid missing or invalid!\n");
> -               return EFI_UNSUPPORTED;
> +               hartid = get_boot_hartid_from_fdt();
> +               if (hartid == U32_MAX) {
> +                       efi_err("/chosen/boot-hartid missing or invalid!\n");
> +                       return EFI_UNSUPPORTED;
> +               }
>         }
>         return EFI_SUCCESS;
>  }
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index ccd4d3f91c98..9822c730207c 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -380,6 +380,7 @@ void efi_native_runtime_setup(void);
>  #define EFI_CONSOLE_OUT_DEVICE_GUID            EFI_GUID(0xd3b36f2c, 0xd551, 0x11d4,  0x9a, 0x46, 0x00, 0x90, 0x27, 0x3f, 0xc1, 0x4d)
>  #define APPLE_PROPERTIES_PROTOCOL_GUID         EFI_GUID(0x91bd12fe, 0xf6c3, 0x44fb,  0xa5, 0xb7, 0x51, 0x22, 0xab, 0x30, 0x3a, 0xe0)
>  #define EFI_TCG2_PROTOCOL_GUID                 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)
>  #define EFI_LOAD_FILE_PROTOCOL_GUID            EFI_GUID(0x56ec3091, 0x954c, 0x11d2,  0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b)
>  #define EFI_LOAD_FILE2_PROTOCOL_GUID           EFI_GUID(0x4006c0c1, 0xfcb3, 0x403e,  0x99, 0x6d, 0x4a, 0x6c, 0x87, 0x24, 0xe0, 0x6d)
>  #define EFI_RT_PROPERTIES_TABLE_GUID           EFI_GUID(0xeb66918a, 0x7eef, 0x402a,  0x84, 0x2e, 0x93, 0x1d, 0x21, 0xc3, 0x8a, 0xe9)
> --
> 2.25.1
>