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

[Daniel P. Berrangé]

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.

> 
> 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.


Regards,
Daniel
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