Re: [kvm-unit-tests PATCH] riscv: lib: sbi_shutdown add exit code.

[Andrew Jones <andrew.jones@linux.dev>]

On Fri, Jun 20, 2025 at 08:50:51AM -0700, Jesse Taube wrote:
> When exiting it may be useful for the sbi implementation to know the
> exit code.
> Add exit code to sbi_shutdown, and use it in exit().
> 
> Signed-off-by: Jesse Taube <jesse@rivosinc.com>
> ---
>  lib/riscv/asm/sbi.h | 2 +-
>  lib/riscv/io.c      | 2 +-
>  lib/riscv/sbi.c     | 4 ++--
>  3 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/riscv/asm/sbi.h b/lib/riscv/asm/sbi.h
> index a5738a5c..de11c109 100644
> --- a/lib/riscv/asm/sbi.h
> +++ b/lib/riscv/asm/sbi.h
> @@ -250,7 +250,7 @@ struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
>  			unsigned long arg3, unsigned long arg4,
>  			unsigned long arg5);
>  
> -void sbi_shutdown(void);
> +void sbi_shutdown(unsigned int code);
>  struct sbiret sbi_hart_start(unsigned long hartid, unsigned long entry, unsigned long sp);
>  struct sbiret sbi_hart_stop(void);
>  struct sbiret sbi_hart_get_status(unsigned long hartid);
> diff --git a/lib/riscv/io.c b/lib/riscv/io.c
> index fb40adb7..02231268 100644
> --- a/lib/riscv/io.c
> +++ b/lib/riscv/io.c
> @@ -150,7 +150,7 @@ void halt(int code);
>  void exit(int code)
>  {
>  	printf("\nEXIT: STATUS=%d\n", ((code) << 1) | 1);
> -	sbi_shutdown();
> +	sbi_shutdown(code & 1);
>  	halt(code);
>  	__builtin_unreachable();
>  }
> diff --git a/lib/riscv/sbi.c b/lib/riscv/sbi.c
> index 2959378f..9dd11e9d 100644
> --- a/lib/riscv/sbi.c
> +++ b/lib/riscv/sbi.c
> @@ -107,9 +107,9 @@ struct sbiret sbi_sse_inject(unsigned long event_id, unsigned long hart_id)
>  	return sbi_ecall(SBI_EXT_SSE, SBI_EXT_SSE_INJECT, event_id, hart_id, 0, 0, 0, 0);
>  }
>  
> -void sbi_shutdown(void)
> +void sbi_shutdown(unsigned int code)
>  {
> -	sbi_ecall(SBI_EXT_SRST, 0, 0, 0, 0, 0, 0, 0);
> +	sbi_ecall(SBI_EXT_SRST, 0, 0, code, 0, 0, 0, 0);

We can't do this because a kvm-unit-tests exit code is not an
SRST::reset_reason[1]. This could result in the SBI implementation
returning an error, or doing something else, rather than shutting
down.

If this is a custom kvm-unit-tests-specific SBI implementation, then
we could pass in a reset_reason in the 0xE0000000 - 0xEFFFFFFF range.

[1] https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/src/ext-sys-reset.adoc#table_srst_system_reset_reasons

Thanks,
drew
 

>  	puts("SBI shutdown failed!\n");
>  }
>  
> -- 
> 2.43.0
> 
> 
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