Re: [RFC PATCH V2 1/1] riscv/efi_stub: Add support for RISCV_EFI_BOOT_PROTOCOL

[Sunil V L <sunilvl@ventanamicro.com>]

On Tue, Mar 22, 2022 at 06:32:20PM -0700, Palmer Dabbelt wrote:
> On Thu, 03 Mar 2022 06:59:44 PST (-0800), 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>
> > ---
> >  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);
> > +};
> > +
> >  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..915ad209d004 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;
> > 
> >  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);
> > +	}
> > +	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("/chosen/boot-hartid missing or invalid!\n");
> 
> Is that the right error message?  IIUC it doesn't really make sense in an
> ACPI context, that's a DT-ism.

Sure. Will update this message in next version.

Thanks
Sunil
> 
> > +			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)