Support cpu0-id of Qemu QMP query-sev-capabilities

It allows libvirt to provide the value of cpu0-id retuned by the Qemu QMP
 command query-sev-capabilities as implemented by the Qemu Patch [1] which
 is merged to Qemu master branch and should be available with Qemu 7.1.
 This is used to get the signed Chip Endorsement Key (CEK) of the CPU of AMD
 system from AMD's Key Distribution Service (KDS).

Similar to  cbitpos, reducedPhysBits, maxGuests & maxESGuests;
 the value of cpu0-id is also provided using 'virsh domcapability'.

[1] https://lore.kernel.org/all/20220228093014.882288-1-dovmurik@linux.ibm.com/

Signed-off-by: Niteesh Dubey <niteesh@linux.ibm.com>
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

include/libvirt/libvirt-host.h

@@ -537,6 +537,17 @@ typedef virNodeMemoryStats *virNodeMemoryStatsPtr;
  */
 # define VIR_NODE_SEV_CERT_CHAIN "cert-chain"
 
+/**
+ * VIR_NODE_SEV_CPU0_ID:
+ *
+ * Macro represents the unique ID of CPU0 (socket 0) needed to retrieve
+ * the signed CEK of the CPU from AMD's Key Distribution Service (KDS),
+ * as VIR_TYPED_PARAMS_STRING.
+ *
+ * Since: 8.4.0
+ */
+# define VIR_NODE_SEV_CPU0_ID "cpu0-id"
+
 /**
  * VIR_NODE_SEV_CBITPOS:
  *

src/conf/domain_capabilities.c

@@ -601,6 +601,10 @@ virDomainCapsFeatureSEVFormat(virBuffer *buf,
                           sev->max_guests);
         virBufferAsprintf(buf, "<maxESGuests>%d</maxESGuests>\n",
                           sev->max_es_guests);
+        if (sev->cpu0_id != NULL) {
+            virBufferAsprintf(buf, "<cpu0Id>%s</cpu0Id>\n",
+                              sev->cpu0_id);
+        }
         virBufferAdjustIndent(buf, -2);
         virBufferAddLit(buf, "</sev>\n");
     }

src/conf/domain_capabilities.h

@@ -185,6 +185,7 @@ typedef struct _virSEVCapability virSEVCapability;
 struct _virSEVCapability {
     char *pdh;
     char *cert_chain;
+    char *cpu0_id;
     unsigned int cbitpos;
     unsigned int reduced_phys_bits;
     unsigned int max_guests;

src/qemu/qemu_capabilities.c

@@ -1957,6 +1957,9 @@ virQEMUCapsSEVInfoCopy(virSEVCapability **dst,
 
     tmp->pdh = g_strdup(src->pdh);
     tmp->cert_chain = g_strdup(src->cert_chain);
+    if (src->cpu0_id != NULL) {
+        tmp->cpu0_id = g_strdup(src->cpu0_id);
+    }
 
     tmp->cbitpos = src->cbitpos;
     tmp->reduced_phys_bits = src->reduced_phys_bits;
@@ -4693,6 +4696,11 @@ virQEMUCapsFormatSEVInfo(virQEMUCaps *qemuCaps, virBuffer *buf)
     virBufferEscapeString(buf, "<pdh>%s</pdh>\n", sev->pdh);
     virBufferEscapeString(buf, "<certChain>%s</certChain>\n",
                           sev->cert_chain);
+    if (sev->cpu0_id != NULL) {
+        virBufferEscapeString(buf, "<cpu0Id>%s</cpu0Id>\n",
+                              sev->cpu0_id);
+    }
+
     virBufferAdjustIndent(buf, -2);
     virBufferAddLit(buf, "</sev>\n");
 }
@@ -6478,6 +6486,10 @@ virQEMUCapsFillDomainFeatureSEVCaps(virQEMUCaps *qemuCaps,
 
     domCaps->sev->pdh = g_strdup(cap->pdh);
     domCaps->sev->cert_chain = g_strdup(cap->cert_chain);
+    if (cap->cpu0_id != NULL) {
+        domCaps->sev->cpu0_id = g_strdup(cap->cpu0_id);
+    }
+
     domCaps->sev->cbitpos = cap->cbitpos;
     domCaps->sev->reduced_phys_bits = cap->reduced_phys_bits;
     domCaps->sev->max_guests = cap->max_guests;

src/qemu/qemu_driver.c

@@ -19861,6 +19861,11 @@ qemuGetSEVInfoToParams(virQEMUCaps *qemuCaps,
                                 VIR_NODE_SEV_CERT_CHAIN, sev->cert_chain) < 0)
         goto cleanup;
 
+    if ((sev->cpu0_id != NULL) &&
+       (virTypedParamsAddString(&sevParams, &n, &maxpar,
+                                VIR_NODE_SEV_CPU0_ID, sev->cpu0_id) < 0))
+        goto cleanup;
+
     if (virTypedParamsAddUInt(&sevParams, &n, &maxpar,
                               VIR_NODE_SEV_CBITPOS, sev->cbitpos) < 0)
         goto cleanup;

src/qemu/qemu_monitor_json.c

@@ -6400,6 +6400,7 @@ qemuMonitorJSONGetSEVCapabilities(qemuMonitor *mon,
     virJSONValue *caps;
     const char *pdh = NULL;
     const char *cert_chain = NULL;
+    const char *cpu0_id = NULL;
     unsigned int cbitpos;
     unsigned int reduced_phys_bits;
     g_autoptr(virSEVCapability) capability = NULL;
@@ -6457,6 +6458,11 @@ qemuMonitorJSONGetSEVCapabilities(qemuMonitor *mon,
 
     capability->cert_chain = g_strdup(cert_chain);
 
+    cpu0_id = virJSONValueObjectGetString(caps, "cpu0-id");
+    if (cpu0_id != NULL) {
+        capability->cpu0_id = g_strdup(cpu0_id);
+    }
+
     capability->cbitpos = cbitpos;
     capability->reduced_phys_bits = reduced_phys_bits;
     *capabilities = g_steal_pointer(&capability);