From: Halil Pasic <pasic@linux.ibm.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: Cornelia Huck <cohuck@redhat.com>,
pair@us.ibm.com, brijesh.singh@amd.com, frankja@linux.ibm.com,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, Eduardo Habkost <ehabkost@redhat.com>,
dgilbert@redhat.com, qemu-ppc@nongnu.org,
Paolo Bonzini <pbonzini@redhat.com>,
mdroth@linux.vnet.ibm.com, Richard Henderson <rth@twiddle.net>
Subject: Re: [RFC v2 00/18] Refactor configuration of guest memory protection
Date: Tue, 9 Jun 2020 12:11:05 +0200 [thread overview]
Message-ID: <20200609121105.50588db9.pasic@linux.ibm.com> (raw)
In-Reply-To: <20200606084409.GL228651@umbus.fritz.box>
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On Sat, 6 Jun 2020 18:44:09 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:
> On Fri, Jun 05, 2020 at 12:55:05PM +0200, Cornelia Huck wrote:
> > On Thu, 21 May 2020 13:42:46 +1000
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >
> > > A number of hardware platforms are implementing mechanisms whereby the
> > > hypervisor does not have unfettered access to guest memory, in order
> > > to mitigate the security impact of a compromised hypervisor.
> > >
> > > AMD's SEV implements this with in-cpu memory encryption, and Intel has
> > > its own memory encryption mechanism. POWER has an upcoming mechanism
> > > to accomplish this in a different way, using a new memory protection
> > > level plus a small trusted ultravisor. s390 also has a protected
> > > execution environment.
> > >
> > > The current code (committed or draft) for these features has each
> > > platform's version configured entirely differently. That doesn't seem
> > > ideal for users, or particularly for management layers.
> > >
> > > AMD SEV introduces a notionally generic machine option
> > > "machine-encryption", but it doesn't actually cover any cases other
> > > than SEV.
> > >
> > > This series is a proposal to at least partially unify configuration
> > > for these mechanisms, by renaming and generalizing AMD's
> > > "memory-encryption" property. It is replaced by a
> > > "guest-memory-protection" property pointing to a platform specific
> > > object which configures and manages the specific details.
> > >
> > > For now this series covers just AMD SEV and POWER PEF. I'm hoping it
> > > can be extended to cover the Intel and s390 mechanisms as well,
> > > though.
> >
> > For s390, there's the 'unpack' cpu facility bit, which is indicated iff
> > the kernel indicates availability of the feature (depending on hardware
> > support). If that cpu facility is available, a guest can choose to
> > transition into protected mode. The current state (protected mode or
> > not) is tracked in the s390 ccw machine.
> >
> > If I understand the series here correctly (I only did a quick
> > read-through), the user has to instruct QEMU to make protection
> > available, via a new machine property that links to an object?
>
> Correct. We used to have basically the same model for POWER - the
> guest just talks to the ultravisor to enter secure mode. But we
> realized that model is broken. You're effectively advertising
> availability of a guest hardware feature based on host kernel or
> hardware properties. That means if you try to migrate from a host
> with the facility to one without, you won't know there's a problem
> until too late.
>
Sorry, I don't quite understand the migration problem described here. If
you have this modeled via a CPU model facility, then you can't migrate
from a host with the facility to one without, except if the user
specified CPU model does not include the facility in question. Or am I
missing something?
Regards,
Halil
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next prev parent reply other threads:[~2020-06-09 10:12 UTC|newest]
Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-21 3:42 [RFC v2 00/18] Refactor configuration of guest memory protection David Gibson
2020-05-21 3:42 ` [RFC v2 01/18] target/i386: sev: Remove unused QSevGuestInfoClass David Gibson
2020-05-29 9:01 ` Philippe Mathieu-Daudé
2020-06-02 3:04 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 02/18] target/i386: sev: Move local structure definitions into .c file David Gibson
2020-05-29 9:03 ` Philippe Mathieu-Daudé
2020-06-02 3:05 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 03/18] target/i386: sev: Rename QSevGuestInfo David Gibson
2020-05-29 9:05 ` Philippe Mathieu-Daudé
2020-06-02 3:06 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 04/18] target/i386: sev: Embed SEVState in SevGuestState David Gibson
2020-05-29 9:09 ` Philippe Mathieu-Daudé
2020-06-04 3:15 ` David Gibson
2020-06-02 3:07 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 05/18] target/i386: sev: Partial cleanup to sev_state global David Gibson
2020-06-02 3:08 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 06/18] target/i386: sev: Remove redundant cbitpos and reduced_phys_bits fields David Gibson
2020-05-29 9:11 ` Philippe Mathieu-Daudé
2020-06-02 3:09 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 07/18] target/i386: sev: Remove redundant policy field David Gibson
2020-06-02 3:13 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 08/18] target/i386: sev: Remove redundant handle field David Gibson
2020-06-02 3:16 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 09/18] target/i386: sev: Unify SEVState and SevGuestState David Gibson
2020-05-29 9:13 ` Philippe Mathieu-Daudé
2020-06-02 3:18 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 10/18] guest memory protection: Add guest memory protection interface David Gibson
2020-05-25 10:27 ` Greg Kurz
2020-06-03 10:09 ` David Gibson
2020-06-02 1:44 ` Richard Henderson
2020-06-03 10:09 ` David Gibson
2020-05-21 3:42 ` [RFC v2 11/18] guest memory protection: Handle memory encrption via interface David Gibson
2020-05-25 10:26 ` Greg Kurz
2020-06-04 3:27 ` David Gibson
2020-06-02 3:21 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 12/18] guest memory protection: Perform KVM init " David Gibson
2020-06-02 3:39 ` Richard Henderson
2020-06-02 3:45 ` Richard Henderson
2020-05-21 3:42 ` [RFC v2 13/18] guest memory protection: Move side effect out of machine_set_memory_encryption() David Gibson
2020-06-02 3:41 ` Richard Henderson
2020-05-21 3:43 ` [RFC v2 14/18] guest memory protection: Rework the "memory-encryption" property David Gibson
2020-06-02 3:54 ` Richard Henderson
2020-06-04 5:56 ` David Gibson
2020-06-04 6:19 ` Thomas Huth
2020-06-04 6:25 ` David Gibson
2020-05-21 3:43 ` [RFC v2 15/18] guest memory protection: Decouple kvm_memcrypt_*() helpers from KVM David Gibson
2020-06-02 4:13 ` Richard Henderson
2020-06-03 10:18 ` David Gibson
2020-05-21 3:43 ` [RFC v2 16/18] guest memory protection: Add Error ** to GuestMemoryProtection::kvm_init David Gibson
2020-05-29 9:16 ` Philippe Mathieu-Daudé
2020-06-02 4:15 ` Richard Henderson
2020-05-21 3:43 ` [RFC v2 17/18] spapr: Added PEF based guest memory protection David Gibson
2020-05-25 11:14 ` Greg Kurz
2020-05-29 7:59 ` Ram Pai
2020-06-04 3:46 ` David Gibson
2020-05-21 3:43 ` [RFC v2 18/18] guest memory protection: Alter virtio default properties for protected guests David Gibson
2020-06-05 10:45 ` Cornelia Huck
2020-06-05 16:04 ` Halil Pasic
2020-06-06 20:21 ` Michael S. Tsirkin
2020-06-07 3:07 ` David Gibson
2020-06-09 10:16 ` Cornelia Huck
2020-06-09 15:40 ` Halil Pasic
2020-06-09 15:57 ` Cornelia Huck
2020-06-09 16:01 ` Michael S. Tsirkin
2020-06-10 4:45 ` David Gibson
2020-06-10 4:39 ` David Gibson
2020-06-10 8:48 ` Cornelia Huck
2020-06-10 10:07 ` David Gibson
2020-06-10 13:21 ` Halil Pasic
2020-05-29 22:19 ` [RFC v2 00/18] Refactor configuration of guest memory protection Sean Christopherson
2020-06-01 9:16 ` Dr. David Alan Gilbert
2020-06-04 3:11 ` David Gibson
2020-06-04 16:20 ` Sean Christopherson
2020-06-04 3:05 ` David Gibson
2020-06-04 4:39 ` Thiago Jung Bauermann
2020-06-04 6:21 ` David Gibson
2020-06-04 21:54 ` Thiago Jung Bauermann
2020-06-04 22:47 ` Paolo Bonzini
2020-06-04 23:30 ` Thiago Jung Bauermann
2020-06-04 23:41 ` Paolo Bonzini
2020-06-05 20:01 ` Thiago Jung Bauermann
2020-06-06 8:24 ` David Gibson
2020-06-08 15:10 ` Thiago Jung Bauermann
2020-06-04 6:44 ` David Gibson
2020-06-04 9:08 ` Greg Kurz
2020-06-06 8:45 ` David Gibson
2020-06-05 10:55 ` Cornelia Huck
2020-06-06 8:44 ` David Gibson
2020-06-09 10:11 ` Halil Pasic [this message]
2020-06-10 4:36 ` David Gibson
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