Shaohua Li wrote: > On Wed, 2007-09-05 at 22:32 +0300, Avi Kivity wrote: > >> [resend due to bad alias expansion resulting in some recipients >> being bogus] >> >> Some hardware and software systems maintain page tables outside the normal >> Linux page tables, which reference userspace memory. This includes >> Infiniband, other RDMA-capable devices, and kvm (with a pending patch). >> >> Because these systems maintain external page tables (and external tlbs), >> Linux cannot demand page this memory and it must be locked. For kvm at >> least, this is a significant reduction in functionality. >> >> This sample patch adds a new mechanism, pte notifiers, that allows drivers >> to register an interest in a changes to ptes. Whenever Linux changes a >> pte, it will call a notifier to allow the driver to adjust the external >> page table and flush its tlb. >> >> Note that only one notifier is implemented, ->clear(), but others should be >> similar. >> >> pte notifiers are different from paravirt_ops: they extend the normal >> page tables rather than replace them; and they provide high-level >> information >> such as the vma and the virtual address for the driver to use. >> > Looks great. So for kvm, all guest pages will be vma mapped? > There are lock issues in kvm between kvm lock and page lock. >
Yes, locking will be a headache. > Will shadow page table be still stored in page->private? If yes, the > page->private must be cleaned before add_to_swap. > page->private can be in use by filesystems, so we will need to move rmap somewhere else. -- Any sufficiently difficult bug is indistinguishable from a feature. ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ kvm-devel mailing list kvm-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/kvm-devel
