[libvirt] [PATCH v4 8/8] qemu_driver: hook up query-cpu-model-comparison

[Collin Walling]

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).

s390x can report that the first model (A) is a subset of the second
(B). If A is the hypervisor CPU and a subset of B (the CPU contained
in the XML), then B would not be able to run on this machine and thus
we will report that CPU model B is incompatible.

Signed-off-by: Collin Walling <walling at linux.ibm.com>
Reviewed-by: Daniel Henrique Barboza <danielh413 at gmail.com>
---
 src/qemu/qemu_capabilities.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
 src/qemu/qemu_capabilities.h |  9 +++++++++
 src/qemu/qemu_driver.c       | 11 ++++++++++
 3 files changed, 68 insertions(+)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index a99ebcb..20cb82b 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -5660,3 +5660,51 @@ virQEMUCapsCPUModelBaseline(virQEMUCapsPtr qemuCaps,
     virCPUDefFree(cpu);
     return baseline;
 }
+
+virCPUCompareResult
+virQEMUCapsCPUModelComparison(virQEMUCapsPtr qemuCaps,
+                              const char *libDir,
+                              uid_t runUid,
+                              gid_t runGid,
+                              virCPUDefPtr cpu_a,
+                              virCPUDefPtr cpu_b,
+                              bool failIncompatible)
+{
+    qemuProcessQMPPtr proc = NULL;
+    qemuMonitorCPUModelInfoPtr result = NULL;
+    int ret = -1;
+
+    if (!(proc = qemuProcessQMPNew(qemuCaps->binary, libDir,
+                                   runUid, runGid, false)))
+        goto cleanup;
+
+    if (qemuProcessQMPStart(proc) < 0)
+        goto cleanup;
+
+    if (qemuMonitorGetCPUModelComparison(proc->mon, cpu_a->model,
+                                         cpu_a->nfeatures, cpu_a->features,
+                                         cpu_b->model, cpu_b->nfeatures,
+                                         cpu_b->features, &result) < 0)
+        goto cleanup;
+
+    if (STREQ(result->name, "incompatible") ||
+        STREQ(result->name, "subset"))
+        ret = VIR_CPU_COMPARE_INCOMPATIBLE;
+    else if (STREQ(result->name, "identical"))
+        ret = VIR_CPU_COMPARE_IDENTICAL;
+    else if (STREQ(result->name, "superset"))
+        ret = VIR_CPU_COMPARE_SUPERSET;
+
+    if (failIncompatible && ret == VIR_CPU_COMPARE_INCOMPATIBLE) {
+        ret = VIR_CPU_COMPARE_ERROR;
+        virReportError(VIR_ERR_CPU_INCOMPATIBLE, NULL);
+    }
+
+ cleanup:
+    if (ret < 0)
+        virQEMUCapsLogProbeFailure(qemuCaps->binary);
+
+    qemuMonitorCPUModelInfoFree(result);
+    qemuProcessQMPFree(proc);
+    return ret;
+}
diff --git a/src/qemu/qemu_capabilities.h b/src/qemu/qemu_capabilities.h
index 8afa05c..a62499f 100644
--- a/src/qemu/qemu_capabilities.h
+++ b/src/qemu/qemu_capabilities.h
@@ -673,3 +673,12 @@ virCPUDefPtr virQEMUCapsCPUModelBaseline(virQEMUCapsPtr qemuCaps,
                                         gid_t runGid,
                                         int ncpus,
                                         virCPUDefPtr *cpus);
+
+virCPUCompareResult
+virQEMUCapsCPUModelComparison(virQEMUCapsPtr qemuCaps,
+                              const char *libDir,
+                              uid_t runUid,
+                              gid_t runGid,
+                              virCPUDefPtr cpu_a,
+                              virCPUDefPtr cpu_b,
+                              bool failIncompatible);
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index 37b9c75..3e49c04 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -13446,9 +13446,11 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
 {
     int ret = VIR_CPU_COMPARE_ERROR;
     virQEMUDriverPtr driver = conn->privateData;
+    virQEMUDriverConfigPtr config = driver->config;
     virQEMUCapsPtr qemuCaps = NULL;
     bool failIncompatible;
     virCPUDefPtr hvCPU;
+    virCPUDefPtr cpu;
     virArch arch;
     virDomainVirtType virttype;
 
@@ -13483,6 +13485,14 @@ 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 (virCPUDefParseXMLHelper(xmlCPU, NULL, VIR_CPU_TYPE_AUTO, &cpu) < 0)
+            goto cleanup;
+
+        ret = virQEMUCapsCPUModelComparison(qemuCaps, config->libDir,
+                                            config->user, config->group,
+                                            hvCPU, cpu, failIncompatible);
     } else {
         virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
                        _("comparing with the hypervisor CPU is not supported "
@@ -13490,6 +13500,7 @@ qemuConnectCompareHypervisorCPU(virConnectPtr conn,
     }
 
  cleanup:
+    virCPUDefFree(cpu);
     virObjectUnref(qemuCaps);
     return ret;
 }
-- 
2.7.4