On 05/11/19 15:56, Andrea Arcangeli wrote: >>> I think we should: >>> >>> 1) whitelist to shut off the warnings on demand >> >> Do you mean adding a whitelist to modpost? That would work, though I am >> not sure if the module maintainer (Jessica Yu) would accept that. > > Yes that's exactly what I meant. Ok, thanks. Jessica, the issue here is that we have two (mutually exclusive) modules providing the same interface to a third module. Andrea will check that, when the same symbol is exported by two modules, the second-loaded module correctly fails insmod. If that is okay, we will also need modpost not to warn for these symbols in sym_add_exported. >> The answer is maintainability. My suggestion is that we start looking >> into removing all assignments and tests of kvm_x86_ops, one step at a >> time. Until this is done, unfortunately we won't be able to reap the >> performance benefit. But the advantage is that this can be done in many > > There's not much performance benefit left from the removal > kvm_x86_ops. Indeed; what I mean is that until then we will have to keep the retpolines. Not removing kvm_x86_ops leaves an unsustainable mess in terms of maintainability, therefore we will need to first refactor the code. Once the refactoring is over, kvm_x86_ops can be dropped easily, just like kvm_pmu_ops in this version of the series. The good thing is that the modpost discussion can proceed in parallel. > The removal of kvm_x86_ops is just a badly needed code cleanup and of > course I agree it must happen sooner than later. I'm just trying to > avoid running into rejects on those further commit cleanups too. >> That is good enough to prove the feasibility of the idea, so I agree >> that was a good plan. > > All right, so I'm not exactly sure what's the plan and if it's ok to > do it over time or if I should go ahead doing all logic changes while > the big patch remains out of tree. Yes, the changes to remove tests and assignments to kvm_x86_ops must happen first. I understand that the big patch is a conflict magnet, but once all the refactoring is done it will be very easy to review and it will get in quickly. Paolo
