[PATCH v4 2/9] qemu: introduce SEV feature in hypervisor capabilities

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Extend hypervisor capabilities to include sev feature. When available,
hypervisor supports launching an encrypted VM on AMD platform. The
sev feature tag provides additional details like platform diffie-hellman
key and certificate chain which can be used by the guest owner to
establish a cryptographic session with the SEV firmware to negotiate
keys used for attestation or to provide secret during launch.

Reviewed-by: "Daniel P. Berrangé" <berrange@xxxxxxxxxx>
Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 docs/formatdomaincaps.html.in  | 40 ++++++++++++++++++++++++++++++++++++++++
 docs/schemas/domaincaps.rng    | 20 ++++++++++++++++++++
 src/conf/domain_capabilities.c | 20 ++++++++++++++++++++
 src/conf/domain_capabilities.h |  1 +
 src/qemu/qemu_capabilities.c   |  2 ++
 5 files changed, 83 insertions(+)

diff --git a/docs/formatdomaincaps.html.in b/docs/formatdomaincaps.html.in
index 6bfcaf6..f383141 100644
--- a/docs/formatdomaincaps.html.in
+++ b/docs/formatdomaincaps.html.in
@@ -417,6 +417,12 @@
         &lt;value&gt;3&lt;/value&gt;
       &lt;/enum&gt;
     &lt;/gic&gt;
+    &lt;sev&gt;
+      &lt;pdh&gt; &lt;/pdh&gt;
+      &lt;cert-chain&gt; &lt;/cert-chain&gt;
+      &lt;cbitpos&gt; &lt;/cbitpos&gt;
+      &lt;reduced-phys-bits&gt; &lt;/reduced-phys-bits&gt;
+    &lt;/sev&gt;
   &lt;/features&gt;
 &lt;/domainCapabilities&gt;
 </pre>
@@ -441,5 +447,39 @@
       <code>gic</code> element.</dd>
     </dl>
 
+    <h4><a id="elementsSEV">SEV capabilities</a></h4>
+
+    <p>AMD Secure Encrypted Virtualization (SEV) capabilities are exposed under
+    the <code>sev</code> element.
+    SEV is an extension to the AMD-V architecture which supports running
+    virtual machines (VMs) under the control of a hypervisor. When supported,
+    guest owner can create a VM whose memory contents will be transparently
+    encrypted with a key unique to that VM.
+
+    For more details on SEV feature see:
+      <a href="https://support.amd.com/TechDocs/55766_SEV-KM%20API_Specification.pdf";>
+        SEV API spec</a> and <a href="http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2013/12/AMD_Memory_Encryption_Whitepaper_v7-Public.pdf";>
+        SEV White Paper</a>
+
+    </p>
+
+    <dl>
+      <dt><code>pdh</code></dt>
+      <dd>Platform diffie-hellman key, which can be exported to remote entities
+      which wish to establish a secure transport context with the SEV platform
+      in order to transmit data securely. The key is encoded in base64</dd>
+      <dt><code>cert-chain</code></dt>
+      <dd> Platform certificate chain -- which includes platform endorsement key
+      (PEK), owners certificate authory (OCA) and chip endorsement key (CEK).
+      The certificate chain is encoded in base64.</dd>
+      <dt><code>cbitpos</code></dt>
+      <dd>When memory encryption is enabled, one of the physical address bit
+      (aka the C-bit) is utilized to mark if a memory page is protected. The
+      C-bit position is Hypervisor dependent.</dd>
+      <dt><code>reduced-phys-bits</code></dt>
+      <dd>When memory encryption is enabled, we loose certain bits in physical
+      address space. The number of bits we loose is hypervisor dependent.</dd>
+    </dl>
+
   </body>
 </html>
diff --git a/docs/schemas/domaincaps.rng b/docs/schemas/domaincaps.rng
index 3905318..53b33eb 100644
--- a/docs/schemas/domaincaps.rng
+++ b/docs/schemas/domaincaps.rng
@@ -173,6 +173,9 @@
     <element name='features'>
       <interleave>
         <ref name='gic'/>
+        <optional>
+        <ref name='sev'/>
+        </optional>
       </interleave>
     </element>
   </define>
@@ -184,6 +187,23 @@
     </element>
   </define>
 
+  <define name='sev'>
+    <element name='sev'>
+      <element name='pdh'>
+        <data type='string'/>
+      </element>
+      <element name='cert-chain'>
+        <data type='string'/>
+      </element>
+      <element name='cbitpos'>
+        <data type='unsignedInt'/>
+      </element>
+      <element name='reduced-phys-bits'>
+        <data type='unsignedInt'/>
+      </element>
+    </element>
+  </define>
+
   <define name='value'>
     <zeroOrMore>
       <element name='value'>
diff --git a/src/conf/domain_capabilities.c b/src/conf/domain_capabilities.c
index f7d9be5..082065f 100644
--- a/src/conf/domain_capabilities.c
+++ b/src/conf/domain_capabilities.c
@@ -549,6 +549,25 @@ virDomainCapsFeatureGICFormat(virBufferPtr buf,
     FORMAT_EPILOGUE(gic);
 }
 
+static void
+virDomainCapsFeatureSEVFormat(virBufferPtr buf,
+                              virSEVCapabilityPtr const sev)
+{
+    if (!sev)
+        return;
+
+    virBufferAddLit(buf, "<sev supported='yes'>\n");
+    virBufferAdjustIndent(buf, 2);
+    virBufferAsprintf(buf, "<cbitpos>%d</cbitpos>\n", sev->cbitpos);
+    virBufferAsprintf(buf, "<reduced-phys-bits>%d</reduced-phys-bits>\n",
+                      sev->reduced_phys_bits);
+    virBufferAsprintf(buf, "<pdh>%s</pdh>\n", sev->pdh);
+    virBufferAsprintf(buf, "<cert-chain>%s</cert-chain>\n",
+                      sev->cert_chain);
+    virBufferAdjustIndent(buf, -2);
+    virBufferAddLit(buf, "</sev>\n");
+}
+
 
 char *
 virDomainCapsFormat(virDomainCapsPtr const caps)
@@ -587,6 +606,7 @@ virDomainCapsFormat(virDomainCapsPtr const caps)
     virBufferAdjustIndent(&buf, 2);
 
     virDomainCapsFeatureGICFormat(&buf, &caps->gic);
+    virDomainCapsFeatureSEVFormat(&buf, caps->sev);
 
     virBufferAdjustIndent(&buf, -2);
     virBufferAddLit(&buf, "</features>\n");
diff --git a/src/conf/domain_capabilities.h b/src/conf/domain_capabilities.h
index 72e9daf..2e8596c 100644
--- a/src/conf/domain_capabilities.h
+++ b/src/conf/domain_capabilities.h
@@ -170,6 +170,7 @@ struct _virDomainCaps {
     /* add new domain devices here */
 
     virDomainCapsFeatureGIC gic;
+    virSEVCapabilityPtr sev;
     /* add new domain features here */
 };
 
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 0f6e6fb..3fd4911 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -5787,6 +5787,8 @@ virQEMUCapsFillDomainCaps(virCapsPtr caps,
         virQEMUCapsFillDomainDeviceHostdevCaps(qemuCaps, hostdev) < 0 ||
         virQEMUCapsFillDomainFeatureGICCaps(qemuCaps, domCaps) < 0)
         return -1;
+
+    domCaps->sev = qemuCaps->sevCapabilities;
     return 0;
 }
 
-- 
2.7.4

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