On Thu, Feb 01, 2024 at 08:28:19AM -0800, Sean Christopherson wrote: [...] > Yeah, I let's just make KVM_EXIT_ON_MISSING mutually exclusive with > KVM_MEM_READONLY. KVM (oviously) honors the primary MMU protections, so userspace > can (and does) map read-only memory into the guest without READONLY. As Oliver > pointed out, making the *memslot* RO is intended for use cases where userspace > wants writes to be treated like emulated MMIO. Well, it was clear enough to me what open source VMMs are doing, I was curious if Google's VMM is doing something strange with RO memslots that made the optimization desirable. But it sounds like we're all in agreement that RO memslots aren't consequential for post-copy. > We can always add support in the future in the extremely unlikely event someone > comes along with a legitimate reason for KVM_EXIT_ON_MISSING to play nice with > KVM_MEM_READONLY. +1, the less stupid things we let userspace do the better. -- Thanks, Oliver
