The CPU models assume that the number of workloads (Processes) is equal to the number of threads when using SE mode. This wasn't checked leading to a segfault if there were no workloads. This change makes the error more clear. Change-Id: I9a7b21112b8f819c6eeca944ee0d73ae9ce9a57b Signed-off-by: Jason Lowe-Power <jason@lowepower.com> Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/67937 Reviewed-by: Ayaz Akram <yazakram@ucdavis.edu> Maintainer: Jason Lowe-Power <power.jg@gmail.com> Tested-by: kokoro <noreply+kokoro@google.com>