Re: [PATCH v5 07/18] s390x: protvirt: Inhibit balloon when switching to protected mode

[Christian Borntraeger]

On 26.02.20 15:59, David Hildenbrand wrote:
> On 26.02.20 13:20, Janosch Frank wrote:
>> Ballooning in protected VMs can only be done when the guest shares the
>> pages it gives to the host. Hence, until we have a solution for this
>> in the guest kernel, we inhibit ballooning when switching into
>> protected mode and reverse that once we move out of it.
> 
> I don't understand what you mean here, sorry. zapping a page will mean
> that a fresh one will be faulted in when accessed. And AFAIK, that means
> it will be encrypted again when needed.
> 
> Is that more like the UV will detect this as an integrity issue and
> crash the VM?

yes, the UV will detect a fresh page as an integrity issue.
Only if the page was defined to be shared by the guest, we would avoid the
integrity check.