On Wed, May 18, 2022, Suleiman Souhlal wrote: > On Tue, May 17, 2022 at 4:30 AM Wei Zhang <zhanwei@xxxxxxxxxx> wrote: > > > > > Please don't top-post. From https://people.kernel.org/tglx/notes-about-netiquette: > > > > Ah, I didn't know this should be avoided. Thanks for the info! > > > > > My preference would be to find a more complete, KVM-specific solution. The > > > profiling stuff seems like it's a dead end, i.e. will always be flawed in some > > > way. If this cleanup didn't require a new hypercall then I wouldn't care, but > > > I don't love having to extend KVM's guest/host ABI for something that ideally > > > will become obsolete sooner than later. > > > > I also feel that adding a new hypercall is too much here. A > > KVM-specific solution is definitely better, and the eBPF based > > approach you mentioned sounds like the ultimate solution (at least for > > inspecting exit reasons). > > > > +Suleiman What do you think? The on-going work Sean described sounds > > promising, perhaps we should put this patch aside for the time being. > > I'm ok with that. > That said, the advantage of the current solution is that it already > exists and is very easy to use, by anyone, without having to write any > code. The proposed solution doesn't sound like it will be as easy. My goal/hope is to make the eBPF approach just as easy by providing/building a library of KVM eBPF programs in tools/ so that doing common things like profiling VM-Exits doesn't require reinventing the wheel. And those programs could be used (and thus implicitly tested) by KVM selftests to verify the kernel functionality.
