On Fri, Sep 09, 2022, Emanuele Giuseppe Esposito wrote: > KVM is currently capable of receiving a single memslot update through > the KVM_SET_USER_MEMORY_REGION ioctl. > The problem arises when we want to atomically perform multiple updates, > so that readers of memslot active list avoid seeing incomplete states. > > For example, in RHBZ https://bugzilla.redhat.com/show_bug.cgi?id=1979276 I don't have access. Can you provide a TL;DR? > we see how non atomic updates cause boot failure, because vcpus > will se a partial update (old memslot delete, new one not yet created) > and will crash. Why not simply pause vCPUs in this scenario? This is an awful lot of a complexity to take on for something that appears to be solvable in userspace. And if the issue is related to KVM disallowing the toggling of read-only (can't see the bug), we can likely solve that without needing a new ioctl() that allows userspace to batch an arbitrary number of updates.
