Hi, On a DELL r610 (Intel Xeon L5520) and a Windows guest I have an hardware error. The bug is well known[1][2] and seems fixed with the package 3.5.0-16-generic. But I use 3.5.0-30-generic. Do I need to upgrade to 13.10? Or just the kernel ? Or modify the options of the kvm module? Thanks. [1] https://bugzilla.redhat.com/show_bug.cgi?id=854983 [2] https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1045027 logs: 2013-05-23 15:54:02.306+0000: starting up LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin QEMU_AUDIO_DRV=none /usr/bin/kvm-spice -name windows1 -S -M pc-1.2 -enable-kvm -m 3500 -smp 2,sockets=2,cores=1,threads=1 -uuid d170225e-7367-4ece-4338-6b1811c10c0c -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/windows1.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/srv/kvm/windows1.img,if=none,id=drive-ide0-0-0,format=qcow2 -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -drive file=/srv/iso/windows7ultimate.iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -netdev tap,fd=18,id=hostnet0,vhost=on,vhostfd=19 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:49:32:cc,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -vga std -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 char device redirected to /dev/pts/1 KVM: entry failed, hardware error 0x80000021 If you're running a guest on an Intel machine without unrestricted mode support, the failure can be most likely due to the guest entering an invalid state for Intel VT. For example, the guest maybe running in big real mode which is not supported on less recent Intel processors. EAX=00000010 EBX=00000080 ECX=00000000 EDX=00000080 ESI=0025da4a EDI=0007da4a EBP=00001f20 ESP=00000200 EIP=0000009b EFL=00000002 [-------] CPL=3 II=0 A20=1 SMM=0 HLT=0 ES =0020 00000200 0000ffff 00009300 CS =b000 002b0000 0000ffff 0000f300 SS =0020 00000200 0000ffff 0000f300 DS =0020 00000200 0000ffff 00009300 FS =0020 00000200 0000ffff 00009300 GS =0020 00000200 0000ffff 00009300 LDT=0000 00000000 0000ffff 00008200 TR =0000 00000000 0000ffff 00008b00 GDT= 002b0000 00000027 IDT= 00000000 000003ff CR0=00000010 CR2=00000000 CR3=00000000 CR4=00000000 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000000 Code=02 00 00 ea 91 00 00 00 18 00 0f 20 c0 66 83 e0 fe 0f 22 c0 <66> 31 c0 8e d8 8e c0 8e d0 66 bc 00 04 00 00 8e e0 8e e8 ea 00 00 00 20 00 00 00 20 4a da -- Sebastien Douche <sdouche(a)gmail.com&gt; Twitter: @sdouche / G+: +sdouche