Re: [RFC PATCH 02/14] RISC-V: Add SBI STA extension definitions

Andrew Jones
2023-04-19T08:16:06Z

On Tue, Apr 18, 2023 at 07:43:51PM +0100, Conor Dooley wrote:
> On Mon, Apr 17, 2023 at 12:33:50PM +0200, Andrew Jones wrote:
> > The SBI STA extension enables steal-time accounting. Add the
> > definitions it specifies.
> >
> > Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> > ---
> > arch/riscv/include/asm/sbi.h | 15 +++++++++++++++
> > 1 file changed, 15 insertions(+)
> >
> > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > index 945b7be249c1..485b9ec20399 100644
> > --- a/arch/riscv/include/asm/sbi.h
> > +++ b/arch/riscv/include/asm/sbi.h
> > @@ -30,6 +30,7 @@ enum sbi_ext_id {
> > SBI_EXT_HSM = 0x48534D,
> > SBI_EXT_SRST = 0x53525354,
> > SBI_EXT_PMU = 0x504D55,
> > + SBI_EXT_STA = 0x535441,
>
> What is the sort order of this? Matching the spec ordering, or just
> append-at-the-end?

I don't believe there's an established order. I've been going for spec
order, I think.

>
> Unrelated, but in checking that I saw that your SUSP stuff is in
> master - you planning on resending that series?

I think I need to wait until it's been ratified.

>
> Anyways, this does match the docs - but I'm quite hesitant to leave an
> R-b when it's not merged yet.

I could take your R-b now, and then if the spec changes, I'd drop it
when reposting the PoC after reworking it.

Thanks,
drew

>
> Cheers,
> Conor.
>
> >
> > /* Experimentals extensions must lie within this range */
> > SBI_EXT_EXPERIMENTAL_START = 0x08000000,
> > @@ -236,6 +237,20 @@ enum sbi_pmu_ctr_type {
> > /* Flags defined for counter stop function */
> > #define SBI_PMU_STOP_FLAG_RESET (1 << 0)
> >
> > +/* SBI STA (steal-time accounting) extension */
> > +enum sbi_ext_sta_fid {
> > + SBI_EXT_STA_SET_STEAL_TIME_SHMEM = 0,
> > +};
> > +
> > +struct sbi_sta_struct {
> > + __le32 sequence;
> > + __le32 flags;
> > + __le64 steal;
> > + u8 preempted;
> > + u8 pad[47];
> > +} __packed;
> > +
> > +/* SBI spec version fields */
> > #define SBI_SPEC_VERSION_DEFAULT 0x1
> > #define SBI_SPEC_VERSION_MAJOR_SHIFT 24
> > #define SBI_SPEC_VERSION_MAJOR_MASK 0x7f
> > --
> > 2.39.2
> >
> >
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