I love qemu/libvirt - the crazy thing is if you have two disks and use one to boot Windows, you can mount the disk then boot into that when using Linux and have that running off another video card (I have two in my PC, one AMD and and nVidia).
That works fine.
I do that at work to avoid nuking/tampering with the Windows installation provided to me by IT, while running Linux as my main OS from a second volume.
I sort of have it documented at https://github.com/hotsphink/sfink-tools/blob/master/doc/Vir... though that's really a set of instructions intended for a new PC that a bunch of us at my employer recently received. You just want the `viewsetup` stuff. You probably want to leave off the `--auto` flag, so that it'll prompt you per-partition.
The tool goes to some effort to only expose the specific partitions needed. It also makes the virtual disk exactly match the native disk, copying small partitions (and gaps between them) to files and exposing those over loopback interfaces, so that Windows can go crazy and write over everything and it won't break your Linux setup. (The Linux partitions themselves are exposed as loopback devices to empty sparse files of the right size.)
Get the single script file at https://hg.sr.ht/~sfink/sfink-tools/raw/bin/viewsetup?rev=ti... or check out the full repo at either https://hg.sr.ht/~sfink/sfink-tools/ (mercurial) or https://github.com/hotsphink/sfink-tools (git). I keep both up to date.