Peter, Because x2apic support is emulated in software. On Mon, Jul 22, 2013 at 08:36:05PM +0800, Peter Huang(Peng) wrote: > I traced the qemu process, and find out that host cpuid doesn't support x2apic, > but VM interception seems enabled x2apic. > > with function=1(bit 21 indicates x2apic) > host_cpuid:ecx=0x009ce3bd > guest_cpuid:ecx=0x00b82201 > > On 2013-07-22 19:24, Peter Huang(Peng) wrote: > > Hi, Everyone > > > > I have been encountered a problem recently. > > My box uses Nehalem E5520 CPU, and this model doesn't support x2apic feature. > > I created a VM on KVM, and uses cpu mode=pass-through, I can get the right cpu > > model from the VM, but I can also see that the CPU in the vm supports x2apic. > > > > This seems werid. > > From QEMU's CPU model definition, Nehalem also doesn't support x2apic. > > > > Can anyone explain it? > > > > Thanks to you all! > > > > Below is the cpuinfo from host and guest: > > host: > > fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush > > dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc > > arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf pni dtes64 > > monitor ds_cpl vmx est tm2 ssse3 cx16 xtpr pdcm dca sse4_1 sse4_2 > > popcnt lahf_lm dtherm tpr_shadow vnmi flexpriority ept vpid > > > > vm: > > fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush > > mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc arch_perfmon rep_good > > nopl pni ssse3 cx16 sse4_1 sse4_2 *x2apic *popcnt hypervisor lahf_lm -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
