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

[Yin Li <yin.li@oss.qualcomm.com>]

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@oss.qualcomm.com>
> 
> Reviewed-by: Andre Przywara <andre.przywara@arm.com>
> 
> 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