Xen: how to map vcpu to one logical cpu so that the vcpu is only slightly less powerful than the logical cpu

Xen: how to map vcpu to one logical cpu so that the vcpu is only slightly
less powerful than the logical cpu

I'm used to working with Hyper-V, but I'm now considering moving to Xen
since I'd be working on *nix environments a lot more.
In Hyper-V every logical cpu core gets divided into 8 vcpus that the VMs
can use. This means that each vCPU is 8 times less powerful than the
actual CPU. This is not a problem for most modern applications since they
will just spread the load.
However, I'm running a 9-year old application that can only run on one
core, is unable to multithread. With Hyper-V we hit a wall since the 1/8th
of a logical CPU isn't sufficient to run the application, it would
constantly run at 100% and become quite unstable. I was wondering if this
is different with Xen. The server that it will run on is an 8-core server
(Xeon 1230v3 @ 3.30Ghz with H/T), so I would like to use 2 of those
logical CPU cores and map them directly to two powerful vCPUs, so we
roughly have a one on one relation. I would run the VM on those two so one
can handle the VM load and the other the application load.
Is this at all possible? I know that you can pin vCPUs to certain cores,
but I would like to reserve two logical CPUs to run two powerful vCPUs,
thus pinning them one on one.
Thanks in advance.