Re: [PATCH RFC 09/15] arm_mpam: Fix MSC MMIO window size to use resource_size() instead of end - start

[Yin Li]

On 9/2/2026 9:16 PM, Andre Przywara wrote:
> Hi,
>
> On 8/11/26 15:30, Yin Li wrote:
> > struct resource uses an inclusive end address, so the correct size is
> > end - start + 1. The previous calculation of end - start was off by one,
> > resulting in a mapped window one byte smaller than the actual resource.
> > Use resource_size() which correctly computes end - start + 1.
>
> Yes, thanks for catching this and making a patch. We found this 
> independently during other MPAM work, but no one got around to make a 
> patch ;-)
>
> > Signed-off-by: Yin Li <yin.li@xxxxxxxxxxxxxxxx>
>
> Reviewed-by: Andre Przywara <andre.przywara@xxxxxxx>
>
> So this patch is independent from and non-conflicting with the DT work, 
> so either Ben or James pick this one directly, or you put those kind of 
> fixes first in the series, when you repost.

Hi Andre,

Thanks for the review and the Reviewed-by tag.

Agreed — like the RIS range-check fix, this one is independent of the DT
work, so I'll move it to the front of the series in the next repost.

> Cheers,
> Andre
>
> > ---
> >   drivers/resctrl/mpam_devices.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/resctrl/mpam_devices.c b/drivers/resctrl/ 
> > mpam_devices.c
> > index 1e082fb60e30..5d1854d97371 100644
> > --- a/drivers/resctrl/mpam_devices.c
> > +++ b/drivers/resctrl/mpam_devices.c
> > @@ -2296,7 +2296,7 @@ static struct mpam_msc 
> > *do_mpam_msc_drv_probe(struct platform_device *pdev)
> >               dev_err_once(dev, "Failed to map MSC base address\n");
> >               return ERR_CAST(io);
> >           }
> > -        msc->mapped_hwpage_sz = msc_res->end - msc_res->start;
> > +        msc->mapped_hwpage_sz = resource_size(msc_res);
> >           msc->mapped_hwpage = io;
> >       } else {
> >           return ERR_PTR(-EINVAL);

--
Thx and BRs,
Yin