Re: [PATCH v2 1/1] KVM: s390: pv: fix race when making a page secure

[David Hildenbrand]

On 26.02.25 17:58, Claudio Imbrenda wrote:
> On Wed, 26 Feb 2025 16:05:11 +0100
> David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> > > +int make_hva_secure(struct mm_struct *mm, unsigned long hva, struct uv_cb_header *uvcb)
> > > +{
> > > +	struct folio *folio;
> > > +	spinlock_t *ptelock;
> > > +	pte_t *ptep;
> > > +	int rc;
> > > +
> > > +	ptep = get_locked_valid_pte(mm, hva, &ptelock);
> > > +	if (!ptep)
> > > +		return -ENXIO;
> >
> > You very likely need a pte_write() check we had there before, as you
> > might effectively modify page content by clearing the page.
>
> it's not really needed, but it doesn't hurt either, I'll add a check

Can you elaborate why it is not needed? Would the HW enforce that 
writability check already?

--
Cheers,

David / dhildenb