Re: [PATCH v3 03/14] KVM: s390: pv: leak the ASCE page when destroy fails

[David Hildenbrand]

On 06.08.21 11:32, Claudio Imbrenda wrote:
> On Fri, 6 Aug 2021 09:31:54 +0200
> David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> > On 04.08.21 17:40, Claudio Imbrenda wrote:
> > > When a protected VM is created, the topmost level of page tables of
> > > its ASCE is marked by the Ultravisor; any attempt to use that
> > > memory for protected virtualization will result in failure.
> > >
> > > Only a successful Destroy Configuration UVC will remove the marking.
> > >
> > > When the Destroy Configuration UVC fails, the topmost level of page
> > > tables of the VM does not get its marking cleared; to avoid issues
> > > it must not be used again.
> > >
> > > Since the page becomes in practice unusable, we set it aside and
> > > leak it.
> >
> > Instead of leaking, can't we add it to some list and try again later?
> > Or do we only expect permanent errors?
>
> once the secure VM has been destroyed unsuccessfully, there is nothing
> that can be done, this is a permanent error
>
> > Also, we really should bail out loud (pr_warn) to tell the admin that
> > something really nasty is going on.
>
> when a destroy secure VM UVC fails, there are already other warnings
> printed, no need to add one more

Okay, makes sense then to me, thanks! Might be worth adding some of that 
info to the patch description.

--
Thanks,

David / dhildenb