[PATCH v7 2/9] conf: expose SEV feature in domain 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
(PDH) 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.

Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
---
 docs/formatdomaincaps.html.in  | 30 ++++++++++++++++++++++++++
 docs/schemas/domaincaps.rng    | 14 ++++++++++++
 src/conf/domain_capabilities.c | 19 ++++++++++++++++-
 src/conf/domain_capabilities.h |  1 +
 src/qemu/qemu_capabilities.c   | 48 +++++++++++++++++++++++++++++++++++++++++-
 5 files changed, 110 insertions(+), 2 deletions(-)

diff --git a/docs/formatdomaincaps.html.in b/docs/formatdomaincaps.html.in
index e0814cb..6be553a 100644
--- a/docs/formatdomaincaps.html.in
+++ b/docs/formatdomaincaps.html.in
@@ -435,6 +435,10 @@
     &lt;/gic&gt;
     &lt;vmcoreinfo supported='yes'/&gt;
     &lt;genid supported='yes'/&gt;
+    &lt;sev&gt;
+      &lt;cbitpos&gt;47&lt;/cbitpos&gt;
+      &lt;reduced-phys-bits&gt;1&lt;/reduced-phys-bits&gt;
+    &lt;/sev&gt;
   &lt;/features&gt;
 &lt;/domainCapabilities&gt;
 </pre>
@@ -467,5 +471,31 @@
 
     <p>Reports whether the genid feature can be used by the domain.</p>
 
+    <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.</p>
+
+    <p>
+    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>cbitpos</code></dt>
+      <dd>When memory encryption is enabled, one of the physical address bits
+      (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 lose certain bits in physical
+      address space. The number of bits we lose is hypervisor dependent.</dd>
+    </dl>
+
   </body>
 </html>
diff --git a/docs/schemas/domaincaps.rng b/docs/schemas/domaincaps.rng
index 5ceabb0..1d0a2e1 100644
--- a/docs/schemas/domaincaps.rng
+++ b/docs/schemas/domaincaps.rng
@@ -185,6 +185,9 @@
         <ref name='gic'/>
         <ref name='vmcoreinfo'/>
         <ref name='vmgenid'/>
+        <optional>
+          <ref name='sev'/>
+        </optional>
       </interleave>
     </element>
   </define>
@@ -208,6 +211,17 @@
     </element>
   </define>
 
+  <define name='sev'>
+    <element name='sev'>
+      <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 3589777..54b0878 100644
--- a/src/conf/domain_capabilities.c
+++ b/src/conf/domain_capabilities.c
@@ -88,6 +88,7 @@ virDomainCapsDispose(void *obj)
     VIR_FREE(caps->machine);
     virObjectUnref(caps->cpu.custom);
     virCPUDefFree(caps->cpu.hostModel);
+    virSEVCapabilitiesFree(caps->sev);
 
     virDomainCapsStringValuesFree(&caps->os.loader.values);
 }
@@ -554,6 +555,22 @@ 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);
+    virBufferAdjustIndent(buf, -2);
+    virBufferAddLit(buf, "</sev>\n");
+}
+
 
 char *
 virDomainCapsFormat(virDomainCapsPtr const caps)
@@ -597,9 +614,9 @@ virDomainCapsFormat(virDomainCapsPtr const caps)
     virDomainCapsFeatureGICFormat(&buf, &caps->gic);
     virBufferAsprintf(&buf, "<vmcoreinfo supported='%s'/>\n",
                       caps->vmcoreinfo ? "yes" : "no");
-
     virBufferAsprintf(&buf, "<genid supported='%s'/>\n",
                       caps->genid ? "yes" : "no");
+    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 30b3272..17c1f1c 100644
--- a/src/conf/domain_capabilities.h
+++ b/src/conf/domain_capabilities.h
@@ -176,6 +176,7 @@ struct _virDomainCaps {
     virDomainCapsFeatureGIC gic;
     bool vmcoreinfo;
     bool genid;
+    virSEVCapabilityPtr sev;
     /* add new domain features here */
 };
 
diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 2c3665d..5db444c 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -5145,6 +5145,50 @@ virQEMUCapsFillDomainFeatureGICCaps(virQEMUCapsPtr qemuCaps,
 }
 
 
+/**
+ * virQEMUCapsFillDomainFeatureSEVCaps:
+ * @qemuCaps: QEMU capabilities
+ * @domCaps: domain capabilities
+ *
+ * Take the information about SEV capabilities that has been obtained
+ * using the 'query-sev-capabilities' QMP command and stored in @qemuCaps
+ * and convert it to a form suitable for @domCaps.
+ *
+ * Returns: 0 on success, <0 on failure
+ */
+static int
+virQEMUCapsFillDomainFeatureSEVCaps(virQEMUCapsPtr qemuCaps,
+                                    virDomainCapsPtr domCaps)
+{
+    virSEVCapability *sev;
+    virSEVCapability *cap = qemuCaps->sevCapabilities;
+
+    if (!cap)
+        return 0;
+
+    if (VIR_ALLOC(sev) < 0)
+        return -1;
+
+    if (VIR_STRDUP(sev->pdh, cap->pdh) < 0)
+        goto out;
+
+    if (VIR_STRDUP(sev->cert_chain, cap->cert_chain) < 0)
+        goto out;
+
+    sev->cbitpos = cap->cbitpos;
+    sev->reduced_phys_bits = cap->reduced_phys_bits;
+    domCaps->sev = sev;
+
+    return 0;
+
+ out:
+    VIR_FREE(sev->cert_chain);
+    VIR_FREE(sev->pdh);
+    VIR_FREE(sev);
+    return -1;
+}
+
+
 int
 virQEMUCapsFillDomainCaps(virCapsPtr caps,
                           virDomainCapsPtr domCaps,
@@ -5182,8 +5226,10 @@ virQEMUCapsFillDomainCaps(virCapsPtr caps,
         virQEMUCapsFillDomainDeviceGraphicsCaps(qemuCaps, graphics) < 0 ||
         virQEMUCapsFillDomainDeviceVideoCaps(qemuCaps, video) < 0 ||
         virQEMUCapsFillDomainDeviceHostdevCaps(qemuCaps, hostdev) < 0 ||
-        virQEMUCapsFillDomainFeatureGICCaps(qemuCaps, domCaps) < 0)
+        virQEMUCapsFillDomainFeatureGICCaps(qemuCaps, domCaps) < 0 ||
+        virQEMUCapsFillDomainFeatureSEVCaps(qemuCaps, domCaps) < 0)
         return -1;
+
     return 0;
 }
 
-- 
2.7.4

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