[libvirt] [PATCH] s390: qemu-capabilities: Avoid error message when missing non-kvm host cpu info

[Boris Fiuczynski]

From: "Jason J. Herne" <jjherne at linux.vnet.ibm.com>

Libvirt prints an error on startup when it is missing host cpu model
information for any queried qemu binary. On s390 we only have host cpu model
information for kvm enabled qemu instances. So when virt type is not kvm, this
is actually not an error on s390.

This patch adds virt type as a parameter to virQEMUCapsInitCPUModelS390, and a
new return code 2 for virQEMUCapsInitCPUModel and virQEMUCapsInitCPUModelS390.
If the virt type is not kvm then we skip printing the scary error message
and return 2 because this case is actually expected behavior. The new return
code is meant to differentiate between the failure case and the case where we
simply expect the cpu model information to be unattainable.

Signed-off-by: Jason J. Herne <jjherne at linux.vnet.ibm.com>
Reviewed-by: Boris Fiuczynski <fiuczy at linux.vnet.ibm.com>
Reviewed-by: Marc Hartmayer <mhartmay at linux.vnet.ibm.com>
---
 src/qemu/qemu_capabilities.c | 30 ++++++++++++++++++++++--------
 1 file changed, 22 insertions(+), 8 deletions(-)

diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c
index 3adea66..b073841 100644
--- a/src/qemu/qemu_capabilities.c
+++ b/src/qemu/qemu_capabilities.c
@@ -3306,22 +3306,28 @@ virQEMUCapsCPUFilterFeatures(const char *name,
 /**
  * Returns  0 when host CPU model provided by QEMU was filled in qemuCaps,
  *          1 when the caller should fall back to using virCapsPtr->host.cpu,
+ *          2 when cpu model info is not supported for this configuration and
+ *            fall back should not be used.
  *         -1 on error.
  */
 static int
 virQEMUCapsInitCPUModelS390(virQEMUCapsPtr qemuCaps,
                             qemuMonitorCPUModelInfoPtr modelInfo,
                             virCPUDefPtr cpu,
-                            bool migratable)
+                            bool migratable,
+                            virDomainVirtType type)
 {
     size_t i;
 
     if (!modelInfo) {
-        virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("missing host CPU model info from QEMU capabilities "
-                         "for binary %s"),
-                       qemuCaps->binary);
-        return -1;
+        if (type == VIR_DOMAIN_VIRT_KVM) {
+            virReportError(VIR_ERR_INTERNAL_ERROR,
+                           _("missing host CPU model info from QEMU "
+                             "capabilities for binary %s"),
+                           qemuCaps->binary);
+            return -1;
+        }
+        return 2;
     }
 
     if (VIR_STRDUP(cpu->model, modelInfo->name) < 0 ||
@@ -3429,6 +3435,8 @@ virQEMUCapsInitCPUModelX86(virQEMUCapsPtr qemuCaps,
 /**
  * Returns  0 when host CPU model provided by QEMU was filled in qemuCaps,
  *          1 when the caller should fall back to other methods
+ *          2 when cpu model info is not supported for this configuration and
+ *            fall back should not be used.
  *         -1 on error.
  */
 int
@@ -3445,13 +3453,13 @@ virQEMUCapsInitCPUModel(virQEMUCapsPtr qemuCaps,
 
     if (ARCH_IS_S390(qemuCaps->arch)) {
         ret = virQEMUCapsInitCPUModelS390(qemuCaps, cpuData->info,
-                                          cpu, migratable);
+                                          cpu, migratable, type);
     } else if (ARCH_IS_X86(qemuCaps->arch)) {
         ret = virQEMUCapsInitCPUModelX86(qemuCaps, type, cpuData->info,
                                          cpu, migratable);
     }
 
-    if (ret == 0)
+    if (ret == 0 || ret == 2)
         cpu->fallback = VIR_CPU_FALLBACK_FORBID;
 
     return ret;
@@ -3504,6 +3512,12 @@ virQEMUCapsInitHostCPUModel(virQEMUCapsPtr qemuCaps,
                                      virQEMUCapsCPUFilterFeatures,
                                      &qemuCaps->arch) < 0)
             goto error;
+    } else if (rc == 2) {
+        VIR_DEBUG("Qemu does not provide cpu model for arch=%s virttype=%s",
+                  virArchToString(qemuCaps->arch),
+                  virDomainVirtTypeToString(type));
+        virCPUDefFree(cpu);
+        goto cleanup;
     } else if (type == VIR_DOMAIN_VIRT_KVM &&
                virCPUGetHostIsSupported(qemuCaps->arch)) {
         if (!(fullCPU = virCPUGetHost(qemuCaps->arch, VIR_CPU_TYPE_GUEST,
-- 
2.9.4