Support for SMP topology was added by qemu commit dc6b1c09849484fbbc50
prior to 0.12.0, our minimum supported qemu version.

$ git describe --tags dc6b1c09849484fbbc50803307e4c7a3d81eab62
v0.11.0-rc0-449-gdc6b1c0
$ git describe --tags --contains dc6b1c09849484fbbc50803307e4c7a3d81eab
v0.12.0-rc0~1477