On Thu, Jan 09, 2020 at 02:35:46PM -0500, Michael S. Tsirkin wrote: > ``void flush_dcache_page(struct page *page)`` > > Any time the kernel writes to a page cache page, _OR_ > the kernel is about to read from a page cache page and > user space shared/writable mappings of this page potentially > exist, this routine is called. > > > > Also, I believe this is the similar question that Jason has asked in > > V2. Sorry I should mention this earlier, but I didn't address that in > > this series because if we need to do so we probably need to do it > > kvm-wise, rather than only in this series. > > You need to document these things. > > > I feel like it's missing > > probably only because all existing KVM supported archs do not have > > virtual-tagged caches as you mentioned. > > But is that a fact? ARM has such a variety of CPUs, > I can't really tell. Did you research this to make sure? > > > If so, I would prefer if you > > can allow me to ignore that issue until KVM starts to support such an > > arch. > > Document limitations pls. Don't ignore them. Hi, Michael, I failed to find a good place to document about flush_dcache_page() for KVM. Could you give me a suggestion? And I don't know about whether there's any ARM hosts that requires flush_dcache_page(). I think not, because again I didn't see any caller of flush_dcache_page() in KVM code yet. Otherwise I think we should at least call it before the kernel reading kvm_run or after publishing data to kvm_run. However I'm also CCing Drew for this. Thanks, -- Peter Xu
