cpu: Add Nehalem-IBRS CPU model

This is a variant of Nehalem with indirect branch prediction protection.
The only difference between Nehalem and Nehalem-IBRS is the added
"spec-ctrl" feature.

Thus the diff matches QEMU, but the new CPU model itself is different.
The QEMU's versions of both models contain "vme" feature, while this
feature is missing in libvirt's models. While we can't change the
existing Nehalem CPU model, we could add "vme" to Nehalem-IBRS to make
it similar to QEMU, but doing so would fool our CPU detecting code so
that any Nehalem CPU with "vme" feature would be detected as
Nehalem-IBRS CPU without spec-ctrl. Not adding "vme" to Nehalem-IBRS is
safe as QEMU will just provide the feature anyway, which matches what
happens with Nehalem (and new enough machine types).

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>

src/cpu/cpu_map.xml

@@ -875,6 +875,43 @@
       <feature name='tsc'/>
     </model>
 
+    <model name='Nehalem-IBRS'>
+      <signature family='6' model='26'/>
+      <vendor name='Intel'/>
+      <feature name='apic'/>
+      <feature name='clflush'/>
+      <feature name='cmov'/>
+      <feature name='cx16'/>
+      <feature name='cx8'/>
+      <feature name='de'/>
+      <feature name='fpu'/>
+      <feature name='fxsr'/>
+      <feature name='lahf_lm'/>
+      <feature name='lm'/>
+      <feature name='mca'/>
+      <feature name='mce'/>
+      <feature name='mmx'/>
+      <feature name='msr'/>
+      <feature name='mtrr'/>
+      <feature name='nx'/>
+      <feature name='pae'/>
+      <feature name='pat'/>
+      <feature name='pge'/>
+      <feature name='pni'/>
+      <feature name='popcnt'/>
+      <feature name='pse'/>
+      <feature name='pse36'/>
+      <feature name='sep'/>
+      <feature name='spec-ctrl'/>
+      <feature name='sse'/>
+      <feature name='sse2'/>
+      <feature name='sse4.1'/>
+      <feature name='sse4.2'/>
+      <feature name='ssse3'/>
+      <feature name='syscall'/>
+      <feature name='tsc'/>
+    </model>
+
     <model name='Westmere'>
       <signature family='6' model='44'/>
       <vendor name='Intel'/>