qemu_driver: hook up query-cpu-model-comparison

This command is hooked into the virsh hypervisor-cpu-compare command.
As such, the CPU model XML provided to the command will be compared
to the hypervisor CPU contained in the QEMU capabilities file for the
appropriate QEMU binary (for s390x, this CPU definition can be observed
via virsh domcapabilities).

QMP will report that the XML CPU is either identical to, a subset of,
or incompatible with the hypervisor CPU. s390 can also report that
the XML CPU is a "superset" of the hypervisor CPU. This response is
presented as incompatible, as this CPU model would not be able to run
on the hypervisor.
Signed-off-by: NCollin Walling <walling@linux.ibm.com>
Reviewed-by: NDaniel Henrique Barboza <danielh413@gmail.com>
Reviewed-by: NBoris Fiuczynski <fiuczy@linux.ibm.com>
Message-Id: <1568924706-2311-15-git-send-email-walling@linux.ibm.com>
Reviewed-by: NJiri Denemark <jdenemar@redhat.com>

src/qemu/qemu_driver.c

@@ -13632,6 +13632,45 @@ qemuConnectCompareCPU(virConnectPtr conn,
 }
 
 
+static virCPUCompareResult
+qemuConnectCPUModelComparison(virQEMUCapsPtr qemuCaps,
+                              const char *libDir,
+                              uid_t runUid,
+                              gid_t runGid,
+                              virCPUDefPtr cpu_a,
+                              virCPUDefPtr cpu_b,
+                              bool failIncompatible)
+{
+    qemuProcessQMPPtr proc = NULL;
+    char *result = NULL;
+    int ret = VIR_CPU_COMPARE_ERROR;
+
+    if (!(proc = qemuProcessQMPNew(virQEMUCapsGetBinary(qemuCaps),
+                                   libDir, runUid, runGid, false)))
+        goto cleanup;
+
+    if (qemuProcessQMPStart(proc) < 0)
+        goto cleanup;
+
+    if (qemuMonitorGetCPUModelComparison(proc->mon, cpu_a, cpu_b, &result) < 0)
+        goto cleanup;
+
+    if (STREQ(result, "identical"))
+        ret = VIR_CPU_COMPARE_IDENTICAL;
+    else if (STREQ(result, "superset"))
+        ret = VIR_CPU_COMPARE_SUPERSET;
+    else if (failIncompatible)
+        virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
+    else
+        ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+
+ cleanup:
+    VIR_FREE(result);
+    qemuProcessQMPFree(proc);
+    return ret;
+}
+
+
 static int
 qemuConnectCompareHypervisorCPU(virConnectPtr conn,
                                 const char *emulator,
@@ -13643,9 +13682,11 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
 {
     int ret = VIR_CPU_COMPARE_ERROR;
     virQEMUDriverPtr driver = conn->privateData;
+    VIR_AUTOUNREF(virQEMUDriverConfigPtr) cfg = virQEMUDriverGetConfig(driver);
     virQEMUCapsPtr qemuCaps = NULL;
     bool failIncompatible;
     virCPUDefPtr hvCPU;
+    virCPUDefPtr cpu = NULL;
     virArch arch;
     virDomainVirtType virttype;
 
@@ -13680,6 +13721,14 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
 
     if (ARCH_IS_X86(arch)) {
         ret = virCPUCompareXML(arch, hvCPU, xmlCPU, failIncompatible);
+    } else if (ARCH_IS_S390(arch) &&
+               virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_COMPARISON)) {
+        if (virCPUDefParseXMLString(xmlCPU, VIR_CPU_TYPE_AUTO, &cpu) < 0)
+            goto cleanup;
+
+        ret = qemuConnectCPUModelComparison(qemuCaps, cfg->libDir,
+                                            cfg->user, cfg->group,
+                                            hvCPU, cpu, failIncompatible);
     } else {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
                        _("comparing with the hypervisor CPU is not supported "
@@ -13687,6 +13736,7 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
     }
 
  cleanup:
+    virCPUDefFree(cpu);
     virObjectUnref(qemuCaps);
     return ret;
 }