Re: [RESEND PATCH v1 3/9] spmi: pmic-arb: check apid against limits before calling irq handler

[Fenglin Wu]

On 10/13/2021 2:02 AM, Stephen Boyd wrote:
> Quoting Fenglin Wu (2021-09-16 23:32:58)
> > From: David Collins <collinsd@xxxxxxxxxxxxxx>
> >
> > Check that the apid for an SPMI interrupt falls between the
> > min_apid and max_apid that can be handled by the APPS processor
> > before invoking the per-apid interrupt handler:
> > periph_interrupt().
> >
> > This avoids an access violation in rare cases where the status
> > bit is set for an interrupt that is not owned by the APPS
> > processor.
> >
> > Signed-off-by: David Collins <collinsd@xxxxxxxxxxxxxx>
> > Signed-off-by: Fenglin Wu <quic_fenglinw@xxxxxxxxxxx>
> > ---
> Fixes? BTW, a lot of these patches are irqchip specific. It would be
> good to get review from irqchip maintainers. Maybe we should split the
> irqchip driver off via the auxiliary bus so that irqchip maintainers can
> review. Please Cc them on irqchip related patches.
>
> IRQCHIP DRIVERS
> M:      Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> M:      Marc Zyngier <maz@xxxxxxxxxx>
Sure, copied Thomas and Marc for code review.
This is a fix to avoid the register access violation in a case that an
interrupt is fired in a PMIC module which is not owned by APPS
processor.
> >   drivers/spmi/spmi-pmic-arb.c | 6 ++++++
> >   1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
> > index 4d7ad004..c4adc06 100644
> > --- a/drivers/spmi/spmi-pmic-arb.c
> > +++ b/drivers/spmi/spmi-pmic-arb.c
> > @@ -535,6 +535,12 @@ static void pmic_arb_chained_irq(struct irq_desc *desc)
> >                          id = ffs(status) - 1;
> >                          status &= ~BIT(id);
> >                          apid = id + i * 32;
> > +                       if (apid < pmic_arb->min_apid
> > +                           || apid > pmic_arb->max_apid) {
> The || goes on the line above. What about making a local variable for
> first and last and then shifting by 5 in the loop?
>
> int first = pmic_arb->min_apid;
> int last = pmic_arb->max_apid;
>
> for (i = first >> 5; i <= last >> 5; i++)
>
> 	if (apid < first || apid > last)
ACK, will update it following this.
> > +                               WARN_ONCE(true, "spurious spmi irq received for apid=%d\n",
> > +                                       apid);
> Is there any way to recover from this? Or once the mapping is wrong
> we're going to get interrupts that we don't know what to do with
> forever?
This is a rare case that the unexpected interrupt is fired in a module
not owned by APPS process, so the interrupt itself is not expected hence
no need to recover from this but just bail out to avoid following register
access violation.
> > +                               continue;
> > +                       }
> >                          enable = readl_relaxed(
> >                                          ver_ops->acc_enable(pmic_arb, apid));
> >                          if (enable & SPMI_PIC_ACC_ENABLE_BIT)