Hack: libvirt: Support maxphysaddr.

This is a hacky version of libvirt: Support maxphysaddr,
which does it properly over flavor and images,
but needs also a trait upgrade.

Do not port it to later versions, it is implemented
correctly by I98968f6ef1621c9fb4f682c119038e26d62ce381.

With Libvirt v8.7.0+, the <maxphysaddr> sub-element
of the <cpu> element specifies the number of vCPU
physical address bits [1].

[1] https://libvirt.org/news.html#v8-7-0-2022-09-01

Change-Id: If89f71511c050a494657614b789adcdb80297725

nova/conf/workarounds.py

@@ -413,7 +413,12 @@
 This will skip the CPU comparison call at the startup of Compute
 service and lets libvirt handle it.
 """),
-
+    cfg.BoolOpt('libvirt_use_host_maxphysaddr',
+               default=False,
+               help="""
+This is a hack: Pass simply the maxphysaddr from the host to the VM.
+This is to be replaced by the proper libvirt-maxphysaddr-support
+"""),
 ]
 
 

nova/virt/libvirt/config.py

@@ -755,6 +755,36 @@ def __hash__(self):
         return hash(self.name)
 
 
+class LibvirtConfigCPUMaxPhysAddr(LibvirtConfigObject):
+
+    def __init__(self, **kwargs):
+        super(LibvirtConfigCPUMaxPhysAddr, self).__init__(
+            root_name='maxphysaddr', **kwargs)
+
+        self.mode = None
+        self.bits = None
+
+    def parse_dom(self, xmldoc):
+        super(LibvirtConfigCPUMaxPhysAddr, self).parse_dom(xmldoc)
+
+        self.mode = xmldoc.get("mode")
+        self.bits = int(xmldoc.get("bits"))
+
+    def format_dom(self):
+        m = super(LibvirtConfigCPUMaxPhysAddr, self).format_dom()
+
+        m.set("mode", self.mode)
+
+        if self.bits:
+            m.set("bits", str(self.bits))
+
+        return m
+
+
+class LibvirtConfigGuestCPUMaxPhysAddr(LibvirtConfigCPUMaxPhysAddr):
+    pass
+
+
 class LibvirtConfigCPU(LibvirtConfigObject):
 
     def __init__(self, **kwargs):
@@ -769,6 +799,8 @@ def __init__(self, **kwargs):
         self.cores = None
         self.threads = None
 
+        self.maxphysaddr = None
+
         self.features = set()
 
     def parse_dom(self, xmldoc):
@@ -785,6 +817,9 @@ def parse_dom(self, xmldoc):
                 self.sockets = int(c.get("sockets"))
                 self.cores = int(c.get("cores"))
                 self.threads = int(c.get("threads"))
+            elif c.tag == "maxphysaddr":
+                self.maxphysaddr = LibvirtConfigCPUMaxPhysAddr()
+                self.maxphysaddr.parse_dom(c)
             elif c.tag == "feature":
                 f = LibvirtConfigCPUFeature()
                 f.parse_dom(c)
@@ -810,6 +845,9 @@ def format_dom(self):
             top.set("threads", str(self.threads))
             cpu.append(top)
 
+        if self.maxphysaddr is not None:
+            cpu.append(self.maxphysaddr.format_dom())
+
         # sorting the features to allow more predictable tests
         for f in sorted(self.features, key=lambda x: x.name):
             cpu.append(f.format_dom())
@@ -904,6 +942,7 @@ def __init__(self, **kwargs):
         self.mode = None
         self.match = "exact"
         self.numa = None
+        self.maxphysaddr = None
 
     def parse_dom(self, xmldoc):
         super(LibvirtConfigGuestCPU, self).parse_dom(xmldoc)
@@ -914,6 +953,10 @@ def parse_dom(self, xmldoc):
                 numa = LibvirtConfigGuestCPUNUMA()
                 numa.parse_dom(child)
                 self.numa = numa
+            elif child.tag == "maxphysaddr":
+                m = LibvirtConfigGuestCPUMaxPhysAddr()
+                m.parse_dom(child)
+                self.maxphysaddr = m
 
     def format_dom(self):
         cpu = super(LibvirtConfigGuestCPU, self).format_dom()

nova/virt/libvirt/driver.py

@@ -5263,6 +5263,17 @@ def _get_guest_cpu_config(self, flavor, image_meta,
         cpu.threads = topology.threads
         cpu.numa = guest_cpu_numa_config
 
+        if not CONF.workarounds.libvirt_use_host_maxphysaddr:
+            return cpu
+
+        caps = self._host.get_capabilities()
+        if not caps.host.cpu.maxphysaddr:
+            return cpu
+
+        cpu.maxphysaddr = vconfig.LibvirtConfigGuestCPUMaxPhysAddr()
+        cpu.maxphysaddr.mode = caps.host.cpu.maxphysaddr.mode
+        cpu.maxphysaddr.bits = caps.host.cpu.maxphysaddr.bits
+
         return cpu
 
     def _get_guest_disk_config(
@@ -7828,6 +7839,12 @@ def _get_cpu_info(self):
         topology['threads'] = caps.host.cpu.threads
         cpu_info['topology'] = topology
 
+        if caps.host.cpu.maxphysaddr:
+            maxphysaddr = dict()
+            maxphysaddr["mode"] = caps.host.cpu.maxphysaddr.mode
+            maxphysaddr["bits"] = caps.host.cpu.maxphysaddr.bits
+            cpu_info["maxphysaddr"] = maxphysaddr
+
         features = set()
         for f in caps.host.cpu.features:
             features.add(f.name)