On Thu, Dec 05, 2019 at 02:51:15PM +0800, Jason Wang wrote: > > On 2019/12/5 上午3:52, Peter Xu wrote: > > 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. > > > > > > > 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. > > Yeah I agree, because I didn't see how copy_to/from_user() helped to > > do icache/dcache flushings... > > > It looks to me one advantage is that exact the same VA is used by both > userspace and kernel so there will be no alias. Hmm.. but what if the page is mapped more than once in user? Thanks, -- Peter Xu
