Re: [PATCH v2 1/6] KVM: s390: Fix dirty marking in adapter_indicators_set*()

[Christian Borntraeger]

Am 18.08.26 um 15:26 schrieb Matthew Rosato:
> On 8/14/26 12:33 PM, Claudio Imbrenda wrote:
> > When the indicator and/or summary bits are set in the guest, the
> > accessed page was only marked dirty in KVM if the access was performed
> > using the slow path; accesses through the new kvm_arch_set_irq_inatomic
> > fast inject path would not mark the page as dirty.
> >
> > Fix by adding/moving the missing calls to mark_page_dirty(). Note that
> > for the inatomic path set_page_dirty{,_lock}() is not needed as the
> > page stays pinned; the unpin path correctly marks it as dirty.
> >
> > Opportunistically reorder the local variables to be in reverse
> > Christmas tree order and refactor to use guard().
> >
> > Fixes: 1e95e3bc6b05 ("KVM: s390: Enable adapter_indicators_set to use mapped pages")
>
> So I'm not strictly opposed to adding the dirtying on the 'fast path'
> but AFAIU the idea here was to still mark the page as dirty right before
> unpin.
>
> Is it strictly required to dirty the page every time it's touched even
> if it's long-term pinned, so long as we make sure to mark the page dirty
> before we eventually unpin it?

Isnt that important for migration?