Alexey Kardashevskiy <aik@xxxxxxxxx> writes: > In the cover letter (which is not really required for a single patch) > you say the capability will be present for BookE and PR KVM (which > Book3s) but here it is BookE only, is that intentional? A few lines below (falling through) we have: /* We support this only for PR */ r = !hv_enabled; > Also, you need to update Documentation/virtual/kvm/api.txt for the new > capability. After reading which I started wondering could not we just > use existing KVM_CAP_GUEST_DEBUG_HW_BPS? We _could_, but I think that would conflate two different concepts. Single stepping does not necessarily makes use of hardware breakpoints (e.g. Trace Interrupt on Book3s PR). I also think we should use KVM_CAP_GUEST_DEBUG_HW_BPS in the future to let QEMU know about: i) the lack of hardware breakpoints in Book3s and ii) BookE's hardware breakpoints (Instruction Address Compare) that are currently not being reported via HW_BPS.