On Wed, Mar 7, 2012 at 8:19 AM, Avi Kivity <avi(a)redhat.com&gt; wrote: Shortly after I sent the original e-mail I told libvirt to use the host CPU. As discussed in another thread since libvirt uses -nodefconfig, it doesn't really have the correct CPU. I believe the original issue is from the fact that I had an AMD K10 based processor with the errata that was previously causing some issues when it wasn't respected. The default qemu64 processor that libvirt had the guest use did not take into account this errata and causes this issue. I have reverted these CPU settings and will get the monitor information as soon as it occurs again. Providing all the background just to be sure. The host is: processor : 63 vendor_id : AuthenticAMD cpu family : 21 model : 1 model name : AMD Opteron(TM) Processor 6272 stepping : 2 microcode : 0x6000613 cpu MHz : 2099.875 cache size : 2048 KB physical id : 2 siblings : 16 core id : 7 cpu cores : 8 apicid : 79 initial apicid : 79 fpu : yes fpu_exception : yes cpuid level : 13 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm constant_tsc rep_good nopl nonstop_tsc extd_apicid amd_dcm aperfmperf pni pclmulqdq monitor ssse3 cx16 sse4_1 sse4_2 popcnt aes xsave avx lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs xop skinit wdt lwp fma4 nodeid_msr topoext perfctr_core arat cpb npt lbrv svm_lock nrip_save tsc_scale vmcb_clean flushbyasid decodeassists pausefilter pfthreshold bogomips : 4200.08 TLB size : 1536 4K pages clflush size : 64 cache_alignment : 64 address sizes : 48 bits physical, 48 bits virtual power management: ts ttp tm 100mhzsteps hwpstate [9] The guest is: processor : 1 vendor_id : AuthenticAMD cpu family : 6 model : 15 model name : Intel(R) Core(TM)2 Duo CPU T7700 @ 2.40GHz stepping : 11 cpu MHz : 2100.397 cache size : 512 KB fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 10 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall nx mmxext fxsr_opt pdpe1gb lm pni cx16 popcnt lahf_lm cmp_legacy svm cr8legacy abm sse4a misalignsse 3dnowprefetch bogomips : 4200.01 The QEMU command line contains the following: -cpu core2duo,+wdt,+skinit,+osvw,+3dnowprefetch,+misalignsse,+sse4a,+abm,+cr8legacy,+extapic,+svm,+cmp_legacy,+lahf_lm,+rdtscp,+pdpe1gb,+fxsr_opt,+mmxext,+aes,+popcnt,+sse4.2,+sse4.1,+cx16,+ht While libvirt's XML contains: <cpu match='exact'> <model>Opteron_G3</model> <vendor>AMD</vendor> <feature policy='require' name='aes'/> <feature policy='require' name='skinit'/> <feature policy='require' name='vme'/> <feature policy='require' name='mmxext'/> <feature policy='require' name='fxsr_opt'/> <feature policy='require' name='cr8legacy'/> <feature policy='require' name='ht'/> <feature policy='require' name='3dnowprefetch'/> <feature policy='require' name='ssse3'/> <feature policy='require' name='wdt'/> <feature policy='require' name='extapic'/> <feature policy='require' name='pdpe1gb'/> <feature policy='require' name='osvw'/> <feature policy='require' name='sse4.1'/> <feature policy='require' name='cmp_legacy'/> <feature policy='require' name='sse4.2'/> </cpu> What the guest used to be with qemu64 CPU: processor : 1 vendor_id : AuthenticAMD cpu family : 6 model : 3 model name : QEMU Virtual CPU version 0.15.1 stepping : 3 cpu MHz : 2100.026 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 4 wp : yes flags : fpu de pse tsc msr pae mce cx8 apic pge cmov pat mmx fxsr sse sse2 pni popcnt bogomips : 4199.33 I also find it odd that the CPU says its 0.15.1 when -M pc-0.13 is explicitly passed in via the command line. -- Doug Goldstein