On Tue, Feb 27, 2018 at 05:15:30PM +0000, Daniel P. Berrangé wrote:
> 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@xxxxxxx>
> > > > ---
> > > > 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.
<launch-security> is IMHO still rather specific than generic, since we might
need to enable features in the future, which might/might no rely on security,
but add additional attributes to the launch validation, in which case I think
going for something like <launch-control> or simply <launch> and having a
structure similar to the one below:
By having the separate <sev> element you can make the sub-elements depend on
this parent element, since you can't expect other vendors to favour <cbitpos>
which add burden to the documentation to make it clear. Of course, the price
you pay for this is a more complex XML structure.
<launch>
<security>
<sev>
<sev_specific_elements/>
</sev>
</security>
<other_security_unrelated_validation_options/>
</launch>
Erik
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