Re: [PATCH v2] xen: gic-v3: Introduce CONFIG_GICV3_NR_LRS

[Julien Grall <julien@xxxxxxx>]

Hi,

On 08/04/2026 23:24, Luca Fancellu wrote:
> > @@ -203,6 +209,10 @@ static uint64_t gicv3_ich_read_lr(int lr)
> >
> > static void gicv3_ich_write_lr(int lr, uint64_t val)
> > {
> > +    /* WI for unsupported LR */
> > +    if ( lr >= LRS )
> > +        return;
> > +
> >      switch ( lr )
> >      {
> >      case 0:
> Now, since we are using CONFIG_GICV3_NR_LRS or gicv3_info.nr_lrs in 
> gicv3_save_lrs/gicv3_restore_lrs,
> there are other part of the codebase using nr_lrs (gic_get_nr_lrs() is one of 
> them), but all the callers of that
> function will use the HW nr_lrs and not the CONFIG_GICV3_NR_LRS, so I think 
> some work needs to be done
> to align them or there will be mismatches at runtime with possible loss of 
> information.
+1. We need a consistent view for the number of LRs. I could also see a 
use case where the integrator wants to support less LRs than what the HW 
supports (this doesn't seem to be prevented with this patch).
Note, during Xen boot, we may need to zero the LRs which are unused as 
they may potentially contain active interrupts.
Cheers,

--
Julien Grall