[PATCH 0/3] lib: sbi: fix PMU SSE event handling

[Atish Kumar Patra]

On Mon, Dec 9, 2024 at 12:55 AM Clément Léger <cleger at rivosinc.com> wrote:
>
>
>
> On 09/12/2024 09:36, Clément Léger wrote:
> >
> >
> > On 06/12/2024 23:25, Atish Patra wrote:
> >> On Fri, Dec 6, 2024 at 1:00 PM Clément Léger <cleger at rivosinc.com> wrote:
> >>>
> >>> While reworking the Linux SSE support, it appears that the PMU event
> >>> should not be available if the SSCOFPMF extension is not available since
> >>> there would be no IRQ. The specification isn't really clear on that point
> >>> so this is more like a RFC to check that. Ideally, the sse register call
> >>
> >> Can you send a patch for SBI spec ? I think we can call it a local PMU
> >> overflow event
> >> rather than a PMU.
> >
> > Yes sure, that makes more sense.  I'll also modify the possible return
> > value for register to add NOT_SUPPORTED in case some dependencies are
> > missing
>
> While thinking about it, should we actually return ERR_INVALID_PARAM or
> add a new ERR_NOT_SUPPORTED if the event is not supported due to missing
> dependencies ? It seems like it is different but I'm not sure it adds
> any valuable information (ie, the caller is not going to do anything
> special about it)
>

IMO, we should add ERR_NOT_SUPPORTED as ERR_INVALID_PARAM indicates
that event_id
is not valid. But ERR_NOT_SUPPORTED will indicate that event_id is
valid but the firmware doesn't support
this event for some reasons (e.g missing ISA dependency being one of them)

> Clément
>
> >
> > Thanks,
> >
> > Clément
> >
> >>
> >> We can add a note about the Sscofpmf dependency as well.
> >>
> >>> should allow to refuse registering an event if the dependencies are not
> >>> satisfied but does not allow this yet.
> >>>
> >>> Clément Léger (3):
> >>>   lib: sbi: sse: Return a value from the register callback
> >>>   lib: sbi: sse: Disable injection if callbacks are set
> >>>   lib: sbi: pmu: Set a SSE register_cb() for event availability
> >>>
> >>>  include/sbi/sbi_sse.h |  2 +-
> >>>  lib/sbi/sbi_pmu.c     | 11 +++++++++++
> >>>  lib/sbi/sbi_sse.c     | 19 +++++++++++++++++--
> >>>  3 files changed, 29 insertions(+), 3 deletions(-)
> >>>
> >>> --
> >>> 2.45.2
> >>>
> >>>
> >>> --
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> >>> opensbi at lists.infradead.org
> >>> http://lists.infradead.org/mailman/listinfo/opensbi
> >>
> >>
> >>
> >
>