On Tue, Apr 06, 2021 at 12:44:45PM +1000, Nicholas Piggin wrote: > Excerpts from Nicholas Piggin's message of April 5, 2021 11:19 am: > > The code being executed in KVM_GUEST_MODE_SKIP is hypervisor code with > > MSR[IR]=0, so the faults of concern are the d-side ones caused by access > > to guest context by the hypervisor. > > > > Instruction breakpoint interrupts are not a concern here. It's unlikely > > any good would come of causing breaks in this code, but skipping the > > instruction that caused it won't help matters (e.g., skip the mtmsr that > > sets MSR[DR]=0 or clears KVM_GUEST_MODE_SKIP). > > > > [Paul notes: the 0x1300 interrupt was dropped from the architecture a > > long time ago and is not generated by P7, P8, P9 or P10.] > > > > In fact it does not exist in ISA v2.01, which is the earliest supported > > now, but did exist in 600 series designs (some of the earliest 64-bit > > powerpcs), so it could probably be removed entirely. > > Hmm, I looked at a 970 manual and that does have a 0x1300, but 2.01 > (which it implements) does not, if I'm reading correctly. Seems strange > the interrupt would be taken out of the architecture then implemented, > but not mine to wonder why. Maybe I misread something. It was probably put in at Apple's request, since they had been using IABR and the 0x1300 interrupt on the 6xx/7xx/7xxx CPUs. Paul.
