Re: [PATCH] riscv: Move user-visible sbi ext ids to uapi

[Paul Walmsley <pjw@kernel.org>]

Hi,

a few comments:

On Wed, 17 Sep 2025, BillXiang wrote:

> Move those sbi ext ids to uapi because they will be forwarded
> to user space by kvm.
> 
> Signed-off-by: BillXiang <xiangwencheng@lanxincomputing.com>

checkpatch.pl reports several issues with this patch.  Please follow these 
steps before sending patches to the public lists:

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst

> ---
>  arch/riscv/include/asm/sbi.h      | 16 +-----------
>  arch/riscv/include/uapi/asm/sbi.h | 43 +++++++++++++++++++++++++++++++
>  2 files changed, 44 insertions(+), 15 deletions(-)
>  create mode 100644 arch/riscv/include/uapi/asm/sbi.h
> 
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index 341e74238aa0..e196feaabb2e 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -10,13 +10,12 @@
>  #include <linux/types.h>
>  #include <linux/cpumask.h>
>  #include <linux/jump_label.h>
> +#include <uapi/asm/sbi.h>
>  
>  #ifdef CONFIG_RISCV_SBI
>  enum sbi_ext_id {
>  #ifdef CONFIG_RISCV_SBI_V01
>  	SBI_EXT_0_1_SET_TIMER = 0x0,
> -	SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
> -	SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
>  	SBI_EXT_0_1_CLEAR_IPI = 0x3,
>  	SBI_EXT_0_1_SEND_IPI = 0x4,
>  	SBI_EXT_0_1_REMOTE_FENCE_I = 0x5,
> @@ -37,13 +36,6 @@ enum sbi_ext_id {
>  	SBI_EXT_NACL = 0x4E41434C,
>  	SBI_EXT_FWFT = 0x46574654,
>  
> -	/* Experimentals extensions must lie within this range */
> -	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
> -	SBI_EXT_EXPERIMENTAL_END = 0x08FFFFFF,
> -
> -	/* Vendor extensions must lie within this range */
> -	SBI_EXT_VENDOR_START = 0x09000000,
> -	SBI_EXT_VENDOR_END = 0x09FFFFFF,
>  };
>  
>  enum sbi_ext_base_fid {
> @@ -263,12 +255,6 @@ enum sbi_pmu_ctr_type {
>  #define SBI_PMU_STOP_FLAG_RESET BIT(0)
>  #define SBI_PMU_STOP_FLAG_TAKE_SNAPSHOT BIT(1)
>  
> -enum sbi_ext_dbcn_fid {
> -	SBI_EXT_DBCN_CONSOLE_WRITE = 0,
> -	SBI_EXT_DBCN_CONSOLE_READ = 1,
> -	SBI_EXT_DBCN_CONSOLE_WRITE_BYTE = 2,
> -};
> -
>  /* SBI STA (steal-time accounting) extension */
>  enum sbi_ext_sta_fid {
>  	SBI_EXT_STA_STEAL_TIME_SET_SHMEM = 0,
> diff --git a/arch/riscv/include/uapi/asm/sbi.h b/arch/riscv/include/uapi/asm/sbi.h
> new file mode 100644
> index 000000000000..d29ac0abeefe
> --- /dev/null
> +++ b/arch/riscv/include/uapi/asm/sbi.h
> @@ -0,0 +1,43 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +/*
> + * Copyright (C) 2025 Lanxincomputing Corporation or its affiliates.

Most of this file is cut-and-pasted from another kernel file, with 
different copyrights.  When that happens, it's best to add the copyright 
notices from the original file, as the new file appears to be a derivative 
of the initial work.

> + *
> + * Authors:
> + *     BillXiang <xiangwencheng@lanxincomputing.com>

Same for authorship information.

> + */
> +
> +#ifndef _UAPI_ASM_RISCV_SBI_H
> +#define _UAPI_ASM_RISCV_SBI_H
> +
> +
> +enum SBI_EXT_ID {
> +	/*
> +	* The CONSOLE_GETCHAR/CONSOLE_PUTCHAR SBI calls cannot be
> +	* handled in kernel so they will be forwarded to userspace by kvm.
> +	*/
> +	SBI_EXT_0_1_CONSOLE_PUTCHAR = 0x1,
> +	SBI_EXT_0_1_CONSOLE_GETCHAR = 0x2,
> +	/*
> +	* Both SBI experimental and vendor extensions are
> +	* unconditionally forwarded to userspace by kvm.
> +	*/
> +	/* Experimentals extensions must lie within this range */
> +	SBI_EXT_EXPERIMENTAL_START = 0x08000000,
> +	SBI_EXT_EXPERIMENTAL_END = 0x08FFFFFF,
> +
> +	/* Vendor extensions must lie within this range */
> +	SBI_EXT_VENDOR_START = 0x09000000,
> +	SBI_EXT_VENDOR_END = 0x09FFFFFF,
> +};
> +
> +/*
> +* The SBI debug console functions are unconditionally
> +* forwarded to the userspace by kvm.
> +*/
> +enum sbi_ext_dbcn_fid {
> +	SBI_EXT_DBCN_CONSOLE_WRITE = 0,
> +	SBI_EXT_DBCN_CONSOLE_READ = 1,
> +	SBI_EXT_DBCN_CONSOLE_WRITE_BYTE = 2,
> +};
> +
> +#endif /* _UAPI_ASM_RISCV_SBI_H */
> \ No newline at end of file

I do have some broader questions: is this patch really needed?  Is it 
fixing anything that's broken?  These SBI constants aren't defined by the 
kernel; they come from RISC-V standards.


- Paul

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