On Sun, Mar 23, 2008 at 10:50:18AM +0200, Avi Kivity wrote: > btw, when we nuke an spte, don't we lose dirty bit information? That > doesn't matter with madvise(), but it does when removing a pte for other > reasons, say swapping. Don't we need to clear the spte with cmpxchg(), to > make sure the dirty bit is what we think it is?
get_user_pages is always called with dirty=1, so we know PG_dirty will be set on the page_t when the pte is cleared. The invalidate_page method is called by the rmap code just after clearing the pte while the page_t is locked, and while the page is locked PG_dirty shouldn't disappear. So as long as we only map anonymous memory we should be safe. (hugetlbfs wasn't allowed as guest physical memory yet when I wrote that code) But if we want to also call set_page_dirty and check the spte dirty bit, that's sure safe addition to make it less dependent on mmu notifier invocation details (notably PG_lock being set). ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
