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

[Jesse Taube]

On Mon, Jun 23, 2025 at 10:01 AM Andrew Jones <andrew.jones at linux.dev> wrote:
>
> 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 at 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.

Yes that's why there is:
+sbi_shutdown(code & 1);
Admittedly it should probably be:
+sbi_shutdown(!!code);

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

That still doesn't guarantee it to succeed.
In the exit function we can add a fallback like `sbi_shutdown(0);`,
but reason code 1 (System failure) should always work.
If anyone wants to use it for SBI specific codes, that's fine,
but I only added it for the No reason and System failure exit codes.

Thanks,
Jesse Taube.

>
> [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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> > kvm-riscv at lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/kvm-riscv