Preferred CPU model SandyBridge not allowed by hypervisor

[Corinna Vinschen]

Hi,


Friday I switched one of my machines from an Opteron 2382 based
motherboard to a Xeon E5-2640 based one.  I'm using this Fedora 17
machine to run my Windows test VMs using qemu-kvm.  I changed the
Processor configuration setting in virt-manager from Opteron G3 to
SandyBridge and now, whenever I start a VM, I get the message from the
subject line:

  Preferred CPU model SandyBridge not allowed by hypervisor; closest
  supported model will be used

ps -ef | grep kvm shows the following CPU setting:

  /usr/bin/qemu-kvm [...] \
    --cpu core2duo,+lahf_lm,+rdtscp,+pdpe1gb,+avx,+osxsave,+xsave,+aes,\
          +tsc-deadline,+popcnt,+x2apic,+sse4.2,+sse4.1,+dca,+pdcm,+xtpr,\
	  +cx16,+tm2,+est,+smx,+vmx,+ds_cpl,+dtes64,+pclmuldq,+pbe,+tm,\
	  +ht,+ss,+acpi,+ds \
    [...]

I tried to add the following SandyBridge entry to
/etc/qemu/target-x86_64.conf (taken from
http://lists.gnu.org/archive/html/qemu-devel/2012-02/msg03765.html):

  [cpudef]
     name = "SandyBridge"
     level = "0xd"
     vendor = "GenuineIntel"
     family = "6"
     model = "42"
     stepping = "1"
     feature_edx = " sse2 sse fxsr mmx clflush pse36 pat cmov mca pge mtrr sep apic cx8 mce pae msr tsc pse de fpu"
     feature_ecx = "avx xsave aes tsc-deadline popcnt x2apic sse4.2 sse4.1 cx16 ssse3 pclmulqdq sse3"
     extfeature_edx = "i64 rdtscp nx syscall "
     extfeature_ecx = "lahf_lm"
     xlevel = "0x8000000A"
     model_id = "Intel Xeon E312xx (Sandy Bridge)"

This doesn't quite match the host CPUs, since the model number of the
E5-26xx CPUs is 45.  But, anyway, qemu-kvm -cpu ? prints:

  error: feature "tsc-deadline" not available in set
  error: bad option value [feature_ecx = avx xsave aes tsc-deadline popcnt x2apic sse4.2 sse4.1 cx16 ssse3 pclmulqdq sse3]
  x86       Opteron_G3
  x86       Opteron_G2
  x86       Opteron_G1
  x86      SandyBridge
  x86          Nehalem
  [...]

Adding this entry also appears to have no effect on the used cpu settings
when starting the VMs.

I'm using stock F17 qemu-kvm-1.0.1-2.fc17.x86_64.  The VMs are working,
so that's not a pressing issue.  I was just wondering, if full CPU
support is something I can change myself using the stock qemu-kvm, or
if I have to upgrade to the 1.2 virt preview release (or wait for F18)?


Corinna