Re: [libvirt] Preferred CPU model not allowed by hypervisor

From: "Jared" <list-virt(a)legroom.net&gt; To: libvir-list(a)redhat.com Sent: Saturday, July 21, 2012 5:46:18 AM Subject: [libvirt] Preferred CPU model not allowed by hypervisor Hi. I'm having a weird problem where libvirt/qemu/kvm won't let me use the model processor I have defined in my domain's config file. Instead, I get the error message in libvirtd.log that: warning : x86Decode:1346 : Preferred CPU model Nehalem not allowed by hypervisor; closest supported model will be used If I review the qemu log for that particular domain, I see that my CPU has been changed to this: -cpu kvm64,+lahf_lm,+popcnt,+sse4.2,+sse4.1,+ssse3 (in other places, I see it set to core2duo rather than kvm64) However, it *should* be Nehalem. For some background, I'm running lvm on a westmere proc, which is the successor to Nehalem. I'm specifying Nehalem as the target platform, though, to make it easier to migrate to another server if necessary. I do have this same problem if I set this to Westmere, though, so it's not unique to Nehalem. As for support and capabilities, libvirt correctly detects my host CPU as Westmere: $ virsh capabilities | grep model <model>Westmere</model> qemu-kvm does (as far as I can tell) support Nehalem: $ qemu-kvm -cpu ?model | grep Nehalem x86 Nehalem Intel Core i7 9xx (Nehalem Class Core i7) Nehalem is defined in qmeu's target-x86_64.conf: grep Nehalem /etc/qemu/target-x86_64.conf name = "Nehalem" model_id = "Intel Core i7 9xx (Nehalem Class Core i7)" And if I run a cpu check on the processor, it seems to work fine: $ qemu-kvm -cpu Nehalem,check VNC server running on `127.0.0.1:5900' So, I I'm creating the new domain as a virt-install with the qemu-kvm backend as follows: virt-install --name=test --ram=1024 --arch=x86_64 --vcpus=2 --cpu=Nehalem --virt-type=kvm <SNIP> This results in the following cpu configuration: <cpu mode='custom' match='exact'> <model fallback='allow'>Nehalem</model> </cpu> But then, when I start this domain, I get the error message posted above. Any ideas what's going on here? I'm at a loss, and unfortunately I don't have much experience with kvm/libvirt just yet so I don't know what I should be focusing on for troubleshooting. Would appreciate any suggestions or guidance.

Thanks. -- Jared -- libvir-list mailing list libvir-list(a)redhat.com https://www.redhat.com/mailman/listinfo/libvir-list