On Tue, Sep 04, 2018 at 04:00:31PM +0300, Denis Plotnikov wrote: > Hi Peter
Hi, Denis, > > I moved the code to the repository > https://github.com/denis-plotnikov/qemu/tree/background-snapshot-kvm. > the current version includes fixes with respect to your comments for version > 1. > I moved KVM related patches to the end of the branch (formerly patch > series). > Since, the KVM patches and the other parts to modify (vhost an others) are > needless in favor of upcoming userfaltfd, > I would ask you to review the general framework which is able to work with > tcg. > > Thanks in advance! Thank you for pushing the tree. I might have made a mistake before that I thought this work is at least working for TCG, but I think I was wrong. The problem is (I'm trying to repeat Dave's question that you seems haven't yet answered): even for TCG there could be use cases where the process might access guest memory from the kernel space (e.g., vhost, or any system calls that with a guest memory buffer passed in). I'm afraid mprotect() and the whole signal-based mechanism cannot be able to address these page faults, then we'll encounter adhoc errors and we'll need to fix all these places up. Userfaultfd-wp should not have this problem. I think the general idea of the work is good, but I'm not sure whether we can merge the work if we don't settle these issues. Regards, -- Peter Xu
