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

[Christian Borntraeger <borntraeger@de.ibm.com>]

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?