CPU pinning implementation through libvirt

I'll be direct. After learning that QEMU itself has never officially implemented options such as "-vcpu", "-vcpupin", or similar, remaining only as unimplemented commits at their mailing lists, I felt the need of asking here once and for all: How does libvirt actually implements CPU pinning under the hood? There's the xml with the cputune section and all the vcpupins, but does libvirt translates this to QEMU native commands, or what else does it do? Thanks.