On Wed, Dec 04, 2019 at 12:04:53PM +0100, Paolo Bonzini wrote: > On 04/12/19 11:38, Jason Wang wrote: > >> > >> + entry = &ring->dirty_gfns[ring->dirty_index & (ring->size - 1)]; > >> + entry->slot = slot; > >> + entry->offset = offset; > > > > > > Haven't gone through the whole series, sorry if it was a silly question > > but I wonder things like this will suffer from similar issue on > > virtually tagged archs as mentioned in [1]. > > There is no new infrastructure to track the dirty pages---it's just a > different way to pass them to userspace. Did you guys consider using one of the virtio ring formats? Maybe reusing vhost code? If you did and it's not a good fit, this is something good to mention in the commit log. I also wonder about performance numbers - any data here? > > Is this better to allocate the ring from userspace and set to KVM > > instead? Then we can use copy_to/from_user() friends (a little bit slow > > on recent CPUs). > > Yeah, I don't think that would be better than mmap. > > Paolo > > > > [1] https://lkml.org/lkml/2019/4/9/5
