Re: [PATCH v2] xen/riscv: fix out-of-range indexing of the IMSIC per-CPU MSI array

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 9/2/26 4:49 PM, Jan Beulich wrote:
> On 02.09.2026 16:16, Oleksii Kurochko wrote:
> > --- a/xen/arch/riscv/imsic.c
> > +++ b/xen/arch/riscv/imsic.c
> > @@ -326,6 +326,8 @@ int __init imsic_init(const struct dt_device_node *node)
> >       unsigned int nr_parent_irqs, index, nr_handlers = 0;
> >       paddr_t base_addr;
> >       unsigned int nr_mmios;
> > +    /* imsic_cfg.msi[] is indexed by Xen CPU id, so size it accordingly. */
> > +    unsigned int nr_msi = nr_cpu_ids;
> Since there's no calculation involved anymore, is there a reason this
> new variable is still needed? With it dropped, ...
I just thought that nr_msi will be more clear nr_cpu_ids but ...

> > @@ -405,7 +407,18 @@ int __init imsic_init(const struct dt_device_node *node)
> >               continue;
> >           }
> >   
> > +        /*
> > +         * hartid_to_cpuid() returns NR_CPUS for a hart Xen doesn't know, so
> > +         * the range has to be checked before msi[] is indexed at all.
> > +         */
> >           cpu = hartid_to_cpuid(hartid);
> > +        if ( cpu >= nr_msi )
> ... this comparison also will end up looking less odd.
... I was wrong. Will use nr_cpu_ids instead.

Thanks.

~ Oleksii