From: David Hildenbrand <david@redhat.com>
To: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: kvm@vger.kernel.org, cohuck@redhat.com, borntraeger@de.ibm.com,
frankja@linux.ibm.com, thuth@redhat.com, pasic@linux.ibm.com,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
Ulrich.Weigand@de.ibm.com
Subject: Re: [PATCH v3 03/14] KVM: s390: pv: leak the ASCE page when destroy fails
Date: Fri, 6 Aug 2021 13:39:07 +0200 [thread overview]
Message-ID: <f2902086-6c77-eb7d-c4c9-15abb738b214@redhat.com> (raw)
In-Reply-To: <20210806113244.4d0712d2@p-imbrenda>
On 06.08.21 11:32, Claudio Imbrenda wrote:
> On Fri, 6 Aug 2021 09:31:54 +0200
> David Hildenbrand <david@redhat.com> 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
next prev parent reply other threads:[~2021-08-06 11:39 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-04 15:40 [PATCH v3 00/14] KVM: s390: pv: implement lazy destroy Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 01/14] KVM: s390: pv: add macros for UVC CC values Claudio Imbrenda
2021-08-06 7:26 ` David Hildenbrand
2021-08-06 9:34 ` Claudio Imbrenda
2021-08-06 15:15 ` Janosch Frank
2021-08-04 15:40 ` [PATCH v3 02/14] KVM: s390: pv: avoid stall notifications for some UVCs Claudio Imbrenda
2021-08-06 7:30 ` David Hildenbrand
2021-08-06 9:33 ` Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 03/14] KVM: s390: pv: leak the ASCE page when destroy fails Claudio Imbrenda
2021-08-06 7:31 ` David Hildenbrand
2021-08-06 9:32 ` Claudio Imbrenda
2021-08-06 11:39 ` David Hildenbrand [this message]
2021-08-04 15:40 ` [PATCH v3 04/14] KVM: s390: pv: properly handle page flags for protected guests Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 05/14] KVM: s390: pv: handle secure storage violations " Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 06/14] KVM: s390: pv: handle secure storage exceptions for normal guests Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 07/14] KVM: s390: pv: refactor s390_reset_acc Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 08/14] KVM: s390: pv: usage counter instead of flag Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 09/14] KVM: s390: pv: add export before import Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 10/14] KVM: s390: pv: lazy destroy for reboot Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 11/14] KVM: s390: pv: extend lazy destroy to handle shutdown Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 12/14] KVM: s390: pv: module parameter to fence lazy destroy Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 13/14] KVM: s390: pv: add OOM notifier for " Claudio Imbrenda
2021-08-04 15:40 ` [PATCH v3 14/14] KVM: s390: pv: avoid export before import if possible Claudio Imbrenda
2021-08-06 7:10 ` [PATCH v3 00/14] KVM: s390: pv: implement lazy destroy David Hildenbrand
2021-08-06 9:30 ` Claudio Imbrenda
2021-08-06 11:30 ` David Hildenbrand
2021-08-06 13:44 ` Claudio Imbrenda
2021-08-09 8:50 ` David Hildenbrand
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