[libvirt] [PATCH 3/4] conf: introduce sev element in domain

[Daniel P. Berrangé]

On Tue, Feb 27, 2018 at 11:07:25AM -0600, Brijesh Singh wrote:
> 
> 
> On 02/27/2018 05:10 AM, Daniel P. Berrangé wrote:
> > On Mon, Feb 26, 2018 at 11:53:35AM -0600, Brijesh Singh wrote:
> > > Secure Encrypted Virtualization (sev) element is used to provide the guest
> > > owners input parameters used for creating an encrypted VM using AMD SEV
> > > feature. SEV feature supports running encrypted VM under the control of
> > > KVM. Encrypted VMs have their pages (code and data) secured such that only
> > > the guest itself has access to the unencrypted version. Each encrypted VM
> > > is associated with a unique encryption key; if its data is accessed to a
> > > different entity using a different key the encrypted guests data will be
> > > incorrectly decrypted, leading to unintelligible data.
> > > 
> > > QEMU >= 2.12 provides 'sev-guest' object which supports launching encrypted
> > > VMs. A typical command line
> > > 
> > > # $QEMU ... \
> > >     -machine memory-encryption=sev0 \
> > >     -object sev-guest,id=sev0,cbitpos=47,reduced-phys-bits=5 \
> > >     ...
> > > 
> > > Signed-off-by: Brijesh Singh <brijesh.singh at amd.com>
> > > ---
> > >   docs/formatdomain.html.in | 71 +++++++++++++++++++++++++++++++++++++++++++
> > >   src/conf/domain_conf.c    | 64 +++++++++++++++++++++++++++++++++++++++
> > >   src/conf/domain_conf.h    | 18 +++++++++++
> > >   src/qemu/qemu_command.c   | 77 +++++++++++++++++++++++++++++++++++++++++++++++
> > >   4 files changed, 230 insertions(+)
> > 
> > In general we'd expect to see additions to the test suite for any XML
> > changes. eg a qemuxml2xmltest and qemuxml2argvtest addition.
> > 
> 
> 
> Sure, this is my first stab at libvirt and will look into getting familiar
> with test and add them in next round.
> 
> 
> > > 
> > > diff --git a/docs/formatdomain.html.in b/docs/formatdomain.html.in
> > > index 6fd2189cd2f4..d18e3fb1d976 100644
> > > --- a/docs/formatdomain.html.in
> > > +++ b/docs/formatdomain.html.in
> > > @@ -8195,6 +8195,77 @@ qemu-kvm -net nic,model=? /dev/null
> > >       <p>Note: DEA/TDEA is synonymous with DES/TDES.</p>
> > > +    <h3><a id="sev">Secure Encrypted Virtualization (SEV)</a></h3>
> > > +
> > > +    <p>
> > > +       The contents of the <code>sev</code> element is used to provide the
> > > +       guest owners input used for creating an encrypted VM using the AMD
> > > +       Secure Encrypted Virtualization (SEV) feature.
> > > +
> > > +       SEV is an extension to the AMD-V architecture which supports running
> > > +       encrypted virtual machine (VMs) under the control of KVM. Encrypted
> > > +       VMs have their pages (code and data) secured such that only the guest
> > > +       itself has access to the unencrypted version. Each encrypted VM is
> > > +       associated with a unique encryption key; if its data is accessed to a
> > > +       different entity using a different key the encrypted guests data will
> > > +       be incorrectly decrypted, leading to unintelligible data.
> > > +       </p>
> > > +    <pre>
> > > +<domain>
> > > +  ...
> > > +  <sev>
> > > +    <policy> 1 </policy>
> > > +    <cbitpos> 47 </cbitpos>
> > > +    <reduced-phys-bits> 5 </reduced-phys-bits>
> > > +    <session> ... </session>
> > > +    <dh-cert> ... </dh>
> > > +  </sev>
> > 
> > Minor nitpick - since this inheranted SEV specific, I think we could do
> > with having a generic top level element with a type=sev. eg
> > 
> >    <launch-security type="sev">
> >         <policy>...</policy>
> >         <cbitpos>..</cbitpos>
> >         ...etc...
> >    </launch>
> > 
> > then we can plug in custom data if other vendors invent competing
> > solutions to AMD's SEV.
> > 
> 
> I am okay with this, how about <memory-encryption> instead of
> <launch-security>, are you okay with it ?

Memory encryption is a very specific feature. It occurs to me that there
could in future be other features that use launch time validation, that
are not memory encryption related.

Regards,
Daniel
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