Re: [PATCH 13/21] KVM: s390: vsie: Add helper to pin multiple guest pages

[Janosch Frank <frankja@linux.ibm.com>]

On 7/9/26 17:28, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Medium] Incorrect address calculation for unaligned GPAs in `pin_guest_pages`, leading to data corruption for multi-page contiguous buffers.
> --

[...]

> 
> [Severity: Medium]
> Could this address calculation cause issues if the initial gpa is unaligned?
> 
> If a caller passes an unaligned gpa to pin_guest_pages() (for example, 0x1010),
> adding PAGE_SIZE * i propagates this initial page offset to every subsequent
> page. This would mean the calculation requests 0x2010, 0x3010, and so on,
> skipping the guest memory between 0x2000 and 0x200F.
> 
> Would it be safer to align the gpa calculation for the subsequent pages to
> ensure a truly contiguous buffer is correctly pinned?
> 
>> +		if (rc)
>> +			goto err;
>> +		addr[i].gpa = gpa + PAGE_SIZE * i;
>> +		addr[i].hpa = hpa;
>> +	}
When unpinning that shouldn't matter since gpa_to_gfn() removes those 
remaining bits. Are you ever using a hpa other than the index 0 one?

But yeah, there shouldn't be any offsets for follow on pages.