> On Apr 7, 2020, at 3:07 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 07/04/20 23:41, Andy Lutomirski wrote: >> 2. Access to bad memory results in #MC. Sure, #MC is a turd, but >> it’s an *architectural* turd. By all means, have a nice simple PV >> mechanism to tell the #MC code exactly what went wrong, but keep the >> overall flow the same as in the native case. >> >> I think I like #2 much better. It has another nice effect: a good >> implementation will serve as a way to exercise the #MC code without >> needing to muck with EINJ or with whatever magic Tony uses. The >> average kernel developer does not have access to a box with testable >> memory failure reporting. > > I prefer #VE, but I can see how #MC has some appeal. However, #VE has a > mechanism to avoid reentrancy, unlike #MC. How would that be better > than the current mess with an NMI happening in the first few > instructions of the #PF handler? > > It has to be an IST vector due to the possibility of hitting a memory failure right after SYSCALL. I imagine that making #VE use IST would be unfortunate. I think #MC has a mechanism to prevent reentrancy to a limited extent. How does #VE avoid reentrancy?
