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Message-ID: <04ed20b1-e312-dfc2-c314-02750c076681@canonical.com>
Date:   Thu, 19 May 2022 08:17:04 +0200
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Subject: Re: [PATCH V4 1/1] riscv/efi_stub: Add support for
 RISCV_EFI_BOOT_PROTOCOL
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To:     Ard Biesheuvel <ardb@kernel.org>,
        Sunil V L <sunilvl@ventanamicro.com>
Cc:     Palmer Dabbelt <palmer@dabbelt.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Ilias Apalodimas <ilias.apalodimas@linaro.org>,
        Atish Patra <atishp@rivosinc.com>,
        Anup Patel <apatel@ventanamicro.com>,
        Jessica Clarke <jrtc27@jrtc27.com>,
        Abner Chang <abner.chang@hpe.com>,
        linux-efi <linux-efi@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        Palmer Dabbelt <palmer@rivosinc.com>
References: <20220518095646.47548-1-sunilvl@ventanamicro.com>
 <20220518095646.47548-2-sunilvl@ventanamicro.com>
 <CAMj1kXF2N+0zRCNg0Aq9Y8Y35FUaQ1V+swzY__y86sayKW7PPA@mail.gmail.com>
From:   Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
In-Reply-To: <CAMj1kXF2N+0zRCNg0Aq9Y8Y35FUaQ1V+swzY__y86sayKW7PPA@mail.gmail.com>
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On 5/18/22 23:03, Ard Biesheuvel wrote:
> On Wed, 18 May 2022 at 11:57, Sunil V L <sunilvl@ventanamicro.com> wrote:
>>
>> This patch adds the support for getting the boot hart ID in
>> Linux EFI stub using RISCV_EFI_BOOT_PROTOCOL. This protocol
>> is preferred method over existing DT based solution since it
>> works irrespective of DT or ACPI.
>>
>> The specification of the protocol is hosted at:
>> https://github.com/riscv-non-isa/riscv-uefi
>>
>> Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
>> Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
>> Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
>> ---
>>   drivers/firmware/efi/libstub/efistub.h    |  7 ++++++
>>   drivers/firmware/efi/libstub/riscv-stub.c | 29 +++++++++++++++++++----
>>   include/linux/efi.h                       |  1 +
>>   3 files changed, 32 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
>> index edb77b0621ea..aced62a0907e 100644
>> --- a/drivers/firmware/efi/libstub/efistub.h
>> +++ b/drivers/firmware/efi/libstub/efistub.h
>> @@ -720,6 +720,13 @@ union efi_tcg2_protocol {
>>          } mixed_mode;
>>   };
>>
>> +struct riscv_efi_boot_protocol {
>> +       u64 revision;
>> +
>> +       efi_status_t (__efiapi * get_boot_hartid)(struct riscv_efi_boot_protocol *this,
>> +                                                 size_t *boot_hartid);
> 
> size_t is not a EFI type, and your spec uses UINTN here, which is
> equivalent to 'unsigned long'. However, jump_kernel_func() takes a
> unsigned int for the hartid. Please clean this up.

unsigned long and size_t have the same number of bits. This seems to be 
a question of taste where we should follow the maintainer.

jump_kernel_func() assuming boot hart ID to be an unsigned int is not in 
line with the RISC-V ISA which allows to use all xlen bits.

> 
> 
>> +};
>> +
>>   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 9c460843442f..012504f6f9a4 100644
>> --- a/drivers/firmware/efi/libstub/riscv-stub.c
>> +++ b/drivers/firmware/efi/libstub/riscv-stub.c
>> @@ -23,7 +23,7 @@
>>
>>   typedef void __noreturn (*jump_kernel_func)(unsigned int, unsigned long);
>>
>> -static u32 hartid;
>> +static size_t hartid;
>>
> 
> and here
> 
>>   static int get_boot_hartid_from_fdt(void)
>>   {
>> @@ -47,14 +47,33 @@ static int get_boot_hartid_from_fdt(void)
>>          return 0;
>>   }
>>
>> +static efi_status_t get_boot_hartid_from_efi(void)
>> +{
>> +       efi_guid_t boot_protocol_guid = RISCV_EFI_BOOT_PROTOCOL_GUID;
>> +       efi_status_t status;
>> +       struct riscv_efi_boot_protocol *boot_protocol;
>> +
>> +       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, &hartid);

A lot of the kernel code seems to be unfit to handle hart IDs exceeding 
INT_MAX (e.g. sbi_cpu_is_stopped()). Until this is fixed we have to 
treat hartid > INT_MAX as an error.

Best regards

Heinrich

>> +       }
>> +       return status;
>> +}
>> +
>>   efi_status_t check_platform_features(void)
>>   {
>>          int ret;
>> +       efi_status_t status;
>>
>> -       ret = get_boot_hartid_from_fdt();
>> -       if (ret) {
>> -               efi_err("/chosen/boot-hartid missing or invalid!\n");
>> -               return EFI_UNSUPPORTED;
>> +       status = get_boot_hartid_from_efi();
>> +       if (status != EFI_SUCCESS) {
>> +               ret = get_boot_hartid_from_fdt();
>> +               if (ret) {
>> +                       efi_err("Failed to get boot hartid!\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
>>