qemu: command: Support new cpu feature argument syntax

Qemu has abandoned the +/-feature syntax in favor of key=value. Some
architectures (s390) do not support +/-feature. So we update libvirt to handle
both formats.

If we detect a sufficiently new Qemu (indicated by support for qmp
query-cpu-model-expansion) we use key=value else we fall back to +/-feature.

Signed-off-by: Collin L. Walling <walling@linux.vnet.ibm.com>
Signed-off-by: Jason J. Herne <jjherne@linux.vnet.ibm.com>

src/qemu/qemu_command.c

@@ -6664,6 +6664,14 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
         break;
     }
 
+    if (ARCH_IS_S390(def->os.arch) && cpu->features &&
+        !virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION)) {
+        virReportError(VIR_ERR_INTERNAL_ERROR,
+                       _("CPU features not supported by hypervisor for %s "
+                         "architecture"), virArchToString(def->os.arch));
+        goto cleanup;
+    }
+
     if (cpu->vendor_id)
         virBufferAsprintf(buf, ",vendor=%s", cpu->vendor_id);
 
@@ -6671,12 +6679,18 @@ qemuBuildCpuModelArgStr(virQEMUDriverPtr driver,
         switch ((virCPUFeaturePolicy) cpu->features[i].policy) {
         case VIR_CPU_FEATURE_FORCE:
         case VIR_CPU_FEATURE_REQUIRE:
-            virBufferAsprintf(buf, ",+%s", cpu->features[i].name);
+            if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION))
+                virBufferAsprintf(buf, ",%s=on", cpu->features[i].name);
+            else
+                virBufferAsprintf(buf, ",+%s", cpu->features[i].name);
             break;
 
         case VIR_CPU_FEATURE_DISABLE:
         case VIR_CPU_FEATURE_FORBID:
-            virBufferAsprintf(buf, ",-%s", cpu->features[i].name);
+            if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION))
+                virBufferAsprintf(buf, ",%s=off", cpu->features[i].name);
+            else
+                virBufferAsprintf(buf, ",-%s", cpu->features[i].name);
             break;
 
         case VIR_CPU_FEATURE_OPTIONAL:

tests/qemuxml2argvdata/qemuxml2argv-cpu-s390-features.args

@@ -0,0 +1,19 @@
+LC_ALL=C \
+PATH=/bin \
+HOME=/home/test \
+USER=test \
+LOGNAME=test \
+QEMU_AUDIO_DRV=none \
+/usr/bin/qemu-kvm \
+-name guest1 \
+-S \
+-M s390-ccw-virtio \
+-cpu zEC12,dfppc=on,stckf=off \
+-m 214 \
+-smp 1,sockets=1,cores=1,threads=1 \
+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \
+-nographic \
+-nodefaults \
+-monitor unix:/tmp/lib/domain--1-guest1/monitor.sock,server,nowait \
+-no-acpi \
+-boot c

tests/qemuxml2argvdata/qemuxml2argv-cpu-s390-features.xml

@@ -0,0 +1,23 @@
+<domain type='kvm'>
+  <name>guest1</name>
+  <uuid>c7a5fdbd-edaf-9455-926a-d65c16db1809</uuid>
+  <memory unit='KiB'>219100</memory>
+  <currentMemory unit='KiB'>219100</currentMemory>
+  <vcpu placement='static'>1</vcpu>
+  <os>
+    <type arch='s390x' machine='s390-ccw-virtio'>hvm</type>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <cpu mode='custom' match='exact'>
+    <model fallback='forbid'>zEC12</model>
+    <feature policy='require' name='dfppc'/>
+    <feature policy='disable' name='stckf'/>
+  </cpu>
+  <devices>
+      <emulator>/usr/bin/qemu-kvm</emulator>
+      <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvtest.c

@@ -1530,6 +1530,8 @@ mymain(void)
 
     qemuTestSetHostArch(driver.caps, VIR_ARCH_S390X);
     DO_TEST("cpu-s390-zEC12", QEMU_CAPS_KVM, QEMU_CAPS_VIRTIO_CCW, QEMU_CAPS_VIRTIO_S390);
+    DO_TEST("cpu-s390-features", QEMU_CAPS_KVM, QEMU_CAPS_QUERY_CPU_MODEL_EXPANSION);
+    DO_TEST_FAILURE("cpu-s390-features", QEMU_CAPS_KVM);
     qemuTestSetHostArch(driver.caps, VIR_ARCH_NONE);
 
     qemuTestSetHostCPU(driver.caps, cpuHaswell);