Re: [PATCH v5 2/4] firmware: arm_sdei: add SDEI_EVENT_SIGNAL support

[Kiryl Shutsemau]

On Tue, Jun 30, 2026 at 03:51:24AM -0700, Usama Arif wrote:
> On Mon, 29 Jun 2026 16:07:16 +0100 Kiryl Shutsemau <kirill@xxxxxxxxxxxxx> wrote:
> 
> > From: "Kiryl Shutsemau (Meta)" <kas@xxxxxxxxxx>
> > 
> > Add sdei_event_signal(), a thin wrapper over the SDEI_EVENT_SIGNAL call
> > (DEN0054) that makes the software-signalled event (event 0) pending on a
> > target PE -- delivered NMI-like even when that PE has interrupts masked.
> > It takes no locks, so it is safe to call from NMI / crash context.
> > 
> > Signed-off-by: Kiryl Shutsemau (Meta) <kas@xxxxxxxxxx>
> > Reviewed-by: Douglas Anderson <dianders@xxxxxxxxxxxx>
> > ---
> >  drivers/firmware/arm_sdei.c   | 12 ++++++++++++
> >  include/linux/arm_sdei.h      |  6 ++++++
> >  include/uapi/linux/arm_sdei.h |  1 +
> >  3 files changed, 19 insertions(+)
> > 
> > diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
> > index c161cf263547..e8dd2f0f3919 100644
> > --- a/drivers/firmware/arm_sdei.c
> > +++ b/drivers/firmware/arm_sdei.c
> > @@ -339,6 +339,18 @@ static void _ipi_unmask_cpu(void *ignored)
> >  	sdei_unmask_local_cpu();
> >  }
> >  
> > +/*
> > + * Signal the software-signalled event (event 0) to @mpidr. Does nothing
> > + * but the SMC -- no locks, no event lookup -- so it is safe from NMI /
> > + * crash context (e.g. the cross-CPU NMI service).
> > + */
> > +int sdei_event_signal(u32 event_num, u64 mpidr)
> > +{
> > +	return invoke_sdei_fn(SDEI_1_0_FN_SDEI_EVENT_SIGNAL, event_num,
> > +			      mpidr, 0, 0, 0, NULL);
> > +}
> > +NOKPROBE_SYMBOL(sdei_event_signal);
> > +
> 
> Same as patch 1, can this be merged in patch 3? Its good to keep functions
> where they are used.

Patch 3 is big as it is. I don't think folding code that can be a
standalone patch helps the situation.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov