cli: Add --boot refresh-machine-type=yes

This is a virt-xml option to refresh a VM to use the latest machine
type version for the machine type it's currently using. Ex:

pseries-2.11 -> pseries
pc-q35-5.0 -> q35

This is useful for when qemu deprecates and removes the machine type
out from under you, or to pick up bug fixes.

Signed-off-by: Cole Robinson <crobinso@redhat.com>

man/virt-xml.rst

@@ -257,6 +257,17 @@ For any option, use --option=? to see a list of all available sub options, examp
 
 --help output also lists a few general examples. See the EXAMPLES section below for some common examples.
 
+virt-xml specifically has some operations that don't really apply to virt-install
+Examples:
+
+``--boot refresh-machine-type=yes``
+    Refresh the XML ``<os><type machine=X></os>`` value to the latest one
+    that qemu provides. For example, if your VM has a machine type value
+    ``pc-q35-4.0``, this will reset the value to ``q35``, and works
+    similarly with other versioned machine types. Occasionally this is
+    necessary to get enable qemu bug fixes, or when qemu deprecates and
+    removes old machine type values.
+
 
 MISCELLANEOUS OPTIONS
 =====================

tests/data/capabilities/kvm-s390x.xml

@@ -49,24 +49,36 @@
 
   <guest>
     <os_type>hvm</os_type>
-    <arch name="s390x">
+    <arch name='s390x'>
       <wordsize>64</wordsize>
       <emulator>/usr/bin/qemu-system-s390x</emulator>
-      <machine canonical="s390-virtio" maxCpus="255">s390</machine>
-      <machine canonical="s390-ccw-virtio" maxCpus="255">s390-ccw</machine>
-      <domain type="qemu">
-        <emulator>/usr/bin/qemu-system-s390x</emulator>
-      </domain>
-      <domain type="kvm">
-        <emulator>/usr/bin/qemu-system-s390x</emulator>
-        <machine canonical="s390-virtio" maxCpus="255">s390</machine>
-        <machine canonical="s390-ccw-virtio" maxCpus="255">s390-ccw</machine>
-      </domain>
+      <machine maxCpus='248'>s390-ccw-virtio-6.1</machine>
+      <machine canonical='s390-ccw-virtio-6.1' maxCpus='248'>s390-ccw-virtio</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-4.0</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-5.2</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-3.1</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.6</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.12</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.9</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-6.0</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-5.1</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-3.0</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-4.2</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.5</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.11</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.8</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-5.0</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-4.1</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.4</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.10</machine>
+      <machine maxCpus='248'>s390-ccw-virtio-2.7</machine>
+      <domain type='qemu'/>
+      <domain type='kvm'/>
     </arch>
     <features>
       <cpuselection/>
       <deviceboot/>
-      <disksnapshot default="on" toggle="no"/>
+      <disksnapshot default='on' toggle='no'/>
     </features>
   </guest>
 

tests/data/cli/compare/virt-xml-refresh-machine-type.xml

@@ -0,0 +1,17 @@
+<domain type="kvm">
+  <name>test</name>
+  <uuid>6695eb01-f6a4-8304-79aa-97f2502e193f</uuid>
+  <memory unit="KiB">8388608</memory>
+  <currentMemory unit="KiB">2097152</currentMemory>
+  <vcpu placement="static">2</vcpu>
+  <os>
+    <type arch="x86_64" machine="q35">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>
+  </devices>
+</domain>

tests/data/cli/compare/virt-xml-stdin-edit.xml

@@ -1,11 +1,11 @@
-<domain type="test" id="1">
+<domain type="kvm">
   <name>test</name>
   <uuid>6695eb01-f6a4-8304-79aa-97f2502e193f</uuid>
   <memory unit="KiB">8388608</memory>
   <currentMemory unit="KiB">2097152</currentMemory>
   <vcpu placement="static">2</vcpu>
   <os>
-    <type arch="i686">hvm</type>
+    <type arch="x86_64" machine="pc-q35-foobar">hvm</type>
     <boot dev="hd"/>
   </os>
   <clock offset="utc"/>

tests/data/cli/virtxml/virtxml-stdin-edit.xml

@@ -1,11 +1,11 @@
-<domain type='test' id='1'>
+<domain type='kvm'>
   <name>test</name>
   <uuid>6695eb01-f6a4-8304-79aa-97f2502e193f</uuid>
   <memory unit='KiB'>8388608</memory>
   <currentMemory unit='KiB'>2097152</currentMemory>
   <vcpu placement='static'>2</vcpu>
   <os>
-    <type arch='i686'>hvm</type>
+    <type arch='x86_64' machine="pc-q35-foobar">hvm</type>
     <boot dev='hd'/>
   </os>
   <clock offset='utc'/>

tests/test_cli.py

@@ -1316,8 +1316,10 @@ c.add_invalid("test-for-virtxml --edit --graphics password=foo,keymap= --update
 c.add_invalid("--build-xml --memory 10,maxmemory=20", grep="--build-xml not supported for --memory")
 c.add_invalid("test-state-shutoff --edit sparse=no --disk path=blah", grep="Don't know how to match device type 'disk' property 'sparse'")
 c.add_invalid("test --add-device --xml ./@foo=bar", grep="--xml can only be used with --edit")
+c.add_invalid("test-for-virtxml --edit --boot refresh-machine-type=yes", grep="Don't know how to refresh")
 c.add_compare("test --print-xml --edit --vcpus 7", "print-xml")  # test --print-xml
 c.add_compare("--edit --cpu host-passthrough", "stdin-edit", input_file=(_VIRTXMLDIR + "virtxml-stdin-edit.xml"))  # stdin test
+c.add_compare("--connect %(URI-KVM-X86)s --edit --boot refresh-machine-type=yes", "refresh-machine-type", input_file=(_VIRTXMLDIR + "virtxml-stdin-edit.xml"))  # refresh-machine-type test. we need to use stdin XML since we can't get the libvirt testdriver to start with the machine XML we need
 c.add_compare("--build-xml --cpu pentium3,+x2apic", "build-cpu")
 c.add_compare("--build-xml --tpm path=/dev/tpm", "build-tpm")
 c.add_compare("--build-xml --blkiotune weight=100,device0.path=/dev/sdf,device.weight=200,device0.read_bytes_sec=10000,device0.write_bytes_sec=10000,device0.read_iops_sec=20000,device0.write_iops_sec=20000", "build-blkiotune")

tests/test_xmlparse.py

@@ -1137,3 +1137,20 @@ def testControllerAttachedDevices():
 
     # Little test for DeviceAddress.pretty_desc
     assert devs[-1].address.pretty_desc() == "0:0:0:3"
+
+
+def testRefreshMachineType():
+    guest = virtinst.Guest(utils.URIs.openconn(utils.URIs.kvm_x86))
+    guest.os.machine = "pc-i440fx-5.2"
+    guest.refresh_machine_type()
+    assert guest.os.machine == "pc"
+
+    guest = virtinst.Guest(utils.URIs.openconn(utils.URIs.kvm_x86))
+    guest.os.machine = "pc-q35-XYZ"
+    guest.refresh_machine_type()
+    assert guest.os.machine == "q35"
+
+    guest = virtinst.Guest(utils.URIs.openconn(utils.URIs.kvm_s390x))
+    guest.os.machine = "s390-ccw-virtio-12345"
+    guest.refresh_machine_type()
+    assert guest.os.machine == "s390-ccw-virtio"

virtinst/cli.py

@@ -2738,6 +2738,10 @@ class ParserBoot(VirtCLIParser):
     # Option handling #
     ###################
 
+    def refresh_machine_type_cb(self, inst, val, virtarg):
+        if val is True:
+            self.guest.refresh_machine_type()
+
     def set_uefi_cb(self, inst, val, virtarg):
         if not self.editing:
             # From virt-install, we just set this flag, and set_defaults()
@@ -2797,6 +2801,10 @@ class ParserBoot(VirtCLIParser):
         cls.add_arg("fd", None, lookup_cb=None, cb=cls.noset_cb)
         cls.add_arg("network", None, lookup_cb=None, cb=cls.noset_cb)
 
+        cls.add_arg("refresh-machine-type", None,
+                cb=cls.refresh_machine_type_cb,
+                lookup_cb=None, is_onoff=True)
+
         # UEFI depends on these bits, so set them first
         cls.add_arg("os_type", "os_type")
         cls.add_arg("arch", "arch")

virtinst/guest.py

@@ -674,6 +674,43 @@ class Guest(XMLBuilder):
             log.warning(  # pragma: no cover
                     "KVM acceleration not available, using '%s'", self.type)
 
+    def refresh_machine_type(self):
+        """
+        Reset the guests's machine type to the latest 'canonical' machine
+        name that qemu reports. So if my VM is using ancient pc-0.11, we
+        try to turn that into just `pc`
+
+        The algorithm here is to fetch all machine types that are aliases
+        for a stable name (like pc -> pc-i440fx-6.2), and see if our current
+        machine type uses alias as a prefix. This is the format that qemu
+        uses for its stable machine type names.
+        """
+        # We need to unset the machine type first, so we can perform
+        # a successful capsinfo lookup, otherwise we will error when qemu
+        # has deprecated and removed the old machine type
+        original_machine_type = self.os.machine or ""
+        self.os.machine = None
+
+        capsinfo = self.lookup_capsinfo()
+        mobjs = (capsinfo.domain and
+                 capsinfo.domain.machines) or capsinfo.guest.machines
+        canonical_names = [m.name for m in mobjs if m.canonical]
+
+        for machine_alias in canonical_names:
+            if machine_alias == "pc":
+                prefix = "pc-i440fx-"
+            elif machine_alias == "q35":
+                prefix = "pc-q35-"
+            else:
+                # Example: pseries-X, virt-X, s390-ccw-virtio-X
+                prefix = machine_alias + "-"
+
+            if original_machine_type.startswith(prefix):
+                self.os.machine = machine_alias
+                return
+        raise Exception("Don't know how to refresh machine type '%s'" %
+                original_machine_type)
+
     def sync_vcpus_topology(self, defCPUs):
         """
         <cpu> topology count and <vcpus> always need to match. Handle