qemu: Use -machine accel=tcg|kvm when available

This is a better interface to choose accelerator than guessing whether
we should enable or disable kvm to get the right one.

src/qemu/qemu_command.c

@@ -5274,11 +5274,80 @@ no_memory:
     goto cleanup;
 }
 
+static int
+qemuBuildObsoleteAccelArg(virCommandPtr cmd,
+                          const virDomainDefPtr def,
+                          virQEMUCapsPtr qemuCaps)
+{
+    int disableKQEMU = 0;
+    int enableKQEMU = 0;
+    int disableKVM = 0;
+    int enableKVM = 0;
+
+    switch (def->virtType) {
+    case VIR_DOMAIN_VIRT_QEMU:
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU))
+            disableKQEMU = 1;
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
+            disableKVM = 1;
+        break;
+
+    case VIR_DOMAIN_VIRT_KQEMU:
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
+            disableKVM = 1;
+
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ENABLE_KQEMU)) {
+            enableKQEMU = 1;
+        } else if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("the QEMU binary does not support kqemu"));
+            return -1;
+        }
+        break;
+
+    case VIR_DOMAIN_VIRT_KVM:
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU))
+            disableKQEMU = 1;
+
+        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ENABLE_KVM)) {
+            enableKVM = 1;
+        } else if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM)) {
+            virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",
+                           _("the QEMU binary does not support kvm"));
+            return -1;
+        }
+        break;
+
+    case VIR_DOMAIN_VIRT_XEN:
+        /* XXX better check for xenner */
+        break;
+
+    default:
+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                       _("the QEMU binary does not support %s"),
+                       virDomainVirtTypeToString(def->virtType));
+        return -1;
+    }
+
+    if (disableKQEMU)
+        virCommandAddArg(cmd, "-no-kqemu");
+    else if (enableKQEMU)
+        virCommandAddArgList(cmd, "-enable-kqemu", "-kernel-kqemu", NULL);
+    if (disableKVM)
+        virCommandAddArg(cmd, "-no-kvm");
+    if (enableKVM)
+        virCommandAddArg(cmd, "-enable-kvm");
+
+    return 0;
+}
+
 static int
 qemuBuildMachineArgStr(virCommandPtr cmd,
                        const virDomainDefPtr def,
                        virQEMUCapsPtr qemuCaps)
 {
+    bool obsoleteAccel = false;
+
     /* This should *never* be NULL, since we always provide
      * a machine in the capabilities data for QEMU. So this
      * check is just here as a safety in case the unexpected
@@ -5297,12 +5366,20 @@ qemuBuildMachineArgStr(virCommandPtr cmd,
                              "with this QEMU binary"));
             return -1;
         }
+        obsoleteAccel = true;
     } else {
         virBuffer buf = VIR_BUFFER_INITIALIZER;
 
         virCommandAddArg(cmd, "-machine");
         virBufferAdd(&buf, def->os.machine, -1);
 
+        if (def->virtType == VIR_DOMAIN_VIRT_QEMU)
+            virBufferAddLit(&buf, ",accel=tcg");
+        else if (def->virtType == VIR_DOMAIN_VIRT_KVM)
+            virBufferAddLit(&buf, ",accel=kvm");
+        else
+            obsoleteAccel = true;
+
         /* To avoid the collision of creating USB controllers when calling
          * machine->init in QEMU, it needs to set usb=off
          */
@@ -5325,6 +5402,10 @@ qemuBuildMachineArgStr(virCommandPtr cmd,
         virCommandAddArgBuffer(cmd, &buf);
     }
 
+    if (obsoleteAccel &&
+        qemuBuildObsoleteAccelArg(cmd, def, qemuCaps) < 0)
+        return -1;
+
     return 0;
 }
 
@@ -5771,10 +5852,6 @@ qemuBuildCommandLine(virConnectPtr conn,
                      enum virNetDevVPortProfileOp vmop)
 {
     int i, j;
-    int disableKQEMU = 0;
-    int enableKQEMU = 0;
-    int disableKVM = 0;
-    int enableKVM = 0;
     const char *emulator;
     char uuid[VIR_UUID_STRING_BUFLEN];
     char *cpu;
@@ -5819,53 +5896,6 @@ qemuBuildCommandLine(virConnectPtr conn,
         (def->virtType == VIR_DOMAIN_VIRT_QEMU))
         virQEMUCapsClear(qemuCaps, QEMU_CAPS_DRIVE_BOOT);
 
-    switch (def->virtType) {
-    case VIR_DOMAIN_VIRT_QEMU:
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU))
-            disableKQEMU = 1;
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
-            disableKVM = 1;
-        break;
-
-    case VIR_DOMAIN_VIRT_KQEMU:
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM))
-            disableKVM = 1;
-
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ENABLE_KQEMU)) {
-            enableKQEMU = 1;
-        } else if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU)) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                           _("the QEMU binary %s does not support kqemu"),
-                           emulator);
-            goto error;
-        }
-        break;
-
-    case VIR_DOMAIN_VIRT_KVM:
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_KQEMU))
-            disableKQEMU = 1;
-
-        if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ENABLE_KVM)) {
-            enableKVM = 1;
-        } else if (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM)) {
-            virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                           _("the QEMU binary %s does not support kvm"),
-                           emulator);
-            goto error;
-        }
-        break;
-
-    case VIR_DOMAIN_VIRT_XEN:
-        /* XXX better check for xenner */
-        break;
-
-    default:
-        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
-                       _("the QEMU binary %s does not support %s"),
-                       emulator, virDomainVirtTypeToString(def->virtType));
-        break;
-    }
-
     cmd = virCommandNew(emulator);
 
     virCommandAddEnvPassCommon(cmd);
@@ -5885,15 +5915,6 @@ qemuBuildCommandLine(virConnectPtr conn,
     if (qemuBuildMachineArgStr(cmd, def, qemuCaps) < 0)
         goto error;
 
-    if (disableKQEMU)
-        virCommandAddArg(cmd, "-no-kqemu");
-    else if (enableKQEMU)
-        virCommandAddArgList(cmd, "-enable-kqemu", "-kernel-kqemu", NULL);
-    if (disableKVM)
-        virCommandAddArg(cmd, "-no-kvm");
-    if (enableKVM)
-        virCommandAddArg(cmd, "-enable-kvm");
-
     if (qemuBuildCpuArgStr(driver, def, emulator, qemuCaps,
                            hostarch, &cpu, &hasHwVirt, !!migrateFrom) < 0)
         goto error;

tests/qemuxml2argvdata/qemuxml2argv-kvm.args

@@ -0,0 +1,4 @@
+LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test \
+/usr/libexec/qemu-kvm -S -machine pc-1.0,accel=kvm -m 4096 \
+-smp 4 -nographic -monitor unix:/tmp/test-monitor,server,nowait \
+-no-acpi -boot c -usb -net none -serial none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-kvm.xml

@@ -0,0 +1,22 @@
+<domain type='kvm'>
+  <name>kvm</name>
+  <uuid>d091ea82-29e6-2e34-3005-f02617b36e87</uuid>
+  <memory unit='KiB'>4194304</memory>
+  <currentMemory unit='KiB'>4194304</currentMemory>
+  <vcpu placement='static'>4</vcpu>
+  <os>
+    <type arch='x86_64' machine='pc-1.0'>hvm</type>
+    <boot dev='hd'/>
+  </os>
+  <clock offset='utc'/>
+  <on_poweroff>destroy</on_poweroff>
+  <on_reboot>restart</on_reboot>
+  <on_crash>destroy</on_crash>
+  <devices>
+    <emulator>/usr/libexec/qemu-kvm</emulator>
+    <controller type='usb' index='0'>
+      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
+    </controller>
+    <memballoon model='none'/>
+  </devices>
+</domain>

tests/qemuxml2argvdata/qemuxml2argv-machine-core-off.args

@@ -1,5 +1,5 @@
 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu \
--S -machine pc,dump-guest-core=off -m 214 -smp 1 -nographic \
+-S -machine pc,accel=tcg,dump-guest-core=off -m 214 -smp 1 -nographic \
 -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
 -hda /dev/HostVG/QEMUGuest1 -net none -serial \
 none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-machine-core-on.args

@@ -1,5 +1,5 @@
 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu \
--S -machine pc,dump-guest-core=on -m 214 -smp 1 -nographic \
+-S -machine pc,accel=tcg,dump-guest-core=on -m 214 -smp 1 -nographic \
 -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
 -hda /dev/HostVG/QEMUGuest1 -net none -serial \
 none -parallel none

tests/qemuxml2argvdata/qemuxml2argv-machine-usb-opt.args

@@ -1,5 +1,5 @@
 LC_ALL=C PATH=/bin HOME=/home/test USER=test LOGNAME=test /usr/bin/qemu \
--S -machine pc,usb=off -m 214 -smp 1 -nographic \
+-S -machine pc,accel=tcg,usb=off -m 214 -smp 1 -nographic \
 -monitor unix:/tmp/test-monitor,server,nowait -no-acpi -boot c -usb \
 -hda /dev/HostVG/QEMUGuest1 -net none -serial \
 none -parallel none

tests/qemuxml2argvtest.c

@@ -372,6 +372,7 @@ mymain(void)
     DO_TEST_FAILURE("machine-core-on", QEMU_CAPS_MACHINE_OPT);
     DO_TEST("machine-usb-opt", QEMU_CAPS_MACHINE_OPT,
             QEMU_CAPS_MACHINE_USB_OPT);
+    DO_TEST("kvm", QEMU_CAPS_MACHINE_OPT);
     DO_TEST("boot-cdrom", NONE);
     DO_TEST("boot-network", NONE);
     DO_TEST("boot-floppy", NONE);