lkml.org 
[lkml]   [2022]   [May]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH V4 1/1] riscv/efi_stub: Add support for RISCV_EFI_BOOT_PROTOCOL
On Thu, 19 May 2022 at 08:17, Heinrich Schuchardt
<heinrich.schuchardt@canonical.com> wrote:
>
>
>
> 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.
>

We use unsigned long wherever the UEFI spec uses UINTN. This is not a
matter of taste, really.

> 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.
>

This is an issue in the core kernel code, not in the EFI stub. As you
pointed out, the ISA implies UINTN / unsigned long here, and if the
startup code cannot deal with that, it can be fixed separately.

\
 
 \ /
  Last update: 2022-05-19 10:16    [W:0.103 / U:0.116 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site