[Xenograph]

It's in the title of the post. You can run your VM in a regular window but at high performance (think gaming and professional stuff that's GPU heavy). You otherwise can't do this without a hardware KVM switch (or tossing the VM and just dual booting). Hardware KVM switches are expensive and often don't work very well. And still, with a KVM switch it wouldn't be running inside a window. It would consume your whole screen.

[mongol]

Is it possible to run Windows in KVM, without the extra GPU or KVM switch, but with degraded performance? Not for gaming, but for example for Office use?

[Anunayj]

yes you can, (Atleast if you can handle the extra CPU and Disk I/O). I think you should checkout winapps [1] which RDP's into the vm to give you a pretty seamless experiance.

P.S. Disk I/O can be a severe bottleneck on HDDs, so try this with a SSD.

[1]. https://github.com/Fmstrat/winapps

[tbr1]

Yes, QXL can do that and has built-in support in e.g. virt-manager. It's not going to be fast, but it does work, and is how installation of Looking Glass can be bootstrapped without a physical monitor attached.