From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Carsten Otte <cotte@de.ibm.com>, Avi Kivity <avi@redhat.com>,
Marcelo Tossati <mtosatti@redhat.com>,
borntrae@linux.vnet.ibm.com, heicars2@linux.vnet.ibm.com,
mschwid2@linux.vnet.ibm.com, huckc@linux.vnet.ibm.com,
KVM <kvm@vger.kernel.org>,
Joachim von Buttlar <joachim_von_buttlar@de.ibm.com>,
Jens Freimann <jfrei@de.ibm.com>,
agraf@suse.de
Subject: Re: [patch 10/12] [PATCH] kvm-s390: storage key interface
Date: Thu, 15 Dec 2011 17:49:19 +0100 [thread overview]
Message-ID: <4EEA250F.9030703@de.ibm.com> (raw)
In-Reply-To: <20111215161106.GA2742@osiris.boeblingen.de.ibm.com>
On 15/12/11 17:11, Heiko Carstens wrote:
> Why again is this needed? Or put in other words: what prevents a guest to
> change the storage key contents via sske of a page that is mapped read-only
> into the guest address space?
> As far as I can see: nothing. Interestingly I could -in theory- do some nice
> stuff like:
> - map a file from a read-only filesystem (which doesn't have a writepage
> aops function) into guest address space
> - let the guest set the change bit in the storage key of a page that belongs
> to that file mapping via sske
> - watch the fun that happens when the host tries to write the page back
Huh?
The guest itself can neither set the dirty bit of the real storage key nor
set the dirty bit the host change bit of the pgste via guest SSKE. The transition
0->1 will only be done in the guest change bit of the pgste. (Otherwise
we would not have a separate guest/host view of change/referenced)
This interface here is for userspace (to change the guest storage key on behalf
of the guest, e.g. for life guest relocation). Since we might have to touch the
real storage key and this is host code millicode will not protect us from doing
stupid things like it does for guest code, we better check before we touch the
real storage key.
Or did I misread your question?
Christian
next prev parent reply other threads:[~2011-12-15 16:49 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-14 12:23 [patch 00/12] Ucontrol patchset V6 Carsten Otte
2011-12-14 12:23 ` [patch 01/12] [PATCH] kvm-s390: add parameter for KVM_CREATE_VM Carsten Otte
2011-12-14 12:23 ` [patch 02/12] [PATCH] kvm-s390-ucontrol: per vcpu address spaces Carsten Otte
2011-12-14 12:23 ` [patch 03/12] [PATCH] kvm-s390-ucontrol: export page faults to user Carsten Otte
2011-12-14 12:23 ` [patch 04/12] [PATCH] kvm-s390-ucontrol: export SIE control block " Carsten Otte
2011-12-14 12:23 ` [patch 05/12] [PATCH] kvm-s390-ucontrol: disable in-kernel handling of SIE intercepts Carsten Otte
2011-12-14 12:23 ` [patch 06/12] [PATCH] kvm-s390-ucontrol: disable in-kernel irq stack Carsten Otte
2011-12-14 12:23 ` [patch 07/12] [PATCH] kvm-s390-ucontrol: interface to inject faults on a vcpu page table Carsten Otte
2011-12-14 12:23 ` [patch 08/12] [PATCH] kvm-s390-ucontrol: disable sca Carsten Otte
2011-12-14 12:23 ` [patch 09/12] [PATCH] kvm-s390: fix assumption for KVM_MAX_VCPUS Carsten Otte
2011-12-14 12:23 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
2011-12-15 10:28 ` Carsten Otte
2011-12-15 16:11 ` Heiko Carstens
2011-12-15 16:49 ` Christian Borntraeger [this message]
2011-12-15 17:18 ` Heiko Carstens
2011-12-15 17:14 ` Martin Schwidefsky
2011-12-14 12:23 ` [patch 11/12] [PATCH] kvm-s390-ucontrol: announce capability for user controlled vms Carsten Otte
2011-12-14 12:23 ` [patch 12/12] [PATCH] kvm-s390: Fix return code for unknown ioctl numbers Carsten Otte
-- strict thread matches above, loose matches on Subject: below --
2011-12-10 12:35 [patch 00/12] Ucontrol patchset V5 Carsten Otte
2011-12-10 12:35 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
2011-12-11 21:57 ` Heiko Carstens
2011-12-12 10:06 ` Martin Schwidefsky
2011-12-09 12:49 [patch 00/12] Ucontrol patchset V4 Carsten Otte
2011-12-09 12:49 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
2011-12-09 13:46 ` Heiko Carstens
2011-12-10 11:36 ` Carsten Otte
2011-12-09 11:23 [patch 00/12] Ucontrol patches V3 Carsten Otte
2011-12-09 11:23 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
2011-12-09 12:04 ` Heiko Carstens
[not found] ` <OFEDB7DC8E.0D8BE463-ONC1257961.004633DF-C1257961.0046C1E7@de.ibm.com>
2011-12-09 13:37 ` Carsten Otte
2011-12-08 9:12 [patch 00/12] Ucontrol patchset V2 Carsten Otte
2011-12-08 9:12 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
2011-12-01 12:57 [patch 00/12] User controlled virtual machines Carsten Otte
2011-12-01 12:57 ` [patch 10/12] [PATCH] kvm-s390: storage key interface Carsten Otte
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