Ian Pratt
2005-Oct-13 17:44 UTC
RE: [Xen-devel] Switching from writeable pagetable to shadow log-dirtyat runtime
> When we switch from writeable pagetable to shadow log-dirty > mode at runtime, there are some PTEs with write-protected; > once we do ptwr_flush(), we write-protect back the page > table. If we simply consult the guest page tables when > building the shadow page tables, then we also copy the write > protection to the shadow pages tables. Since the shadow code > does not have the logic for the writeable page table, the > guest kernel, for exmaple, can see write-protected page > table, resulting a panic. We are experiencing the problem > with PAE log-dirty mode (that we are working on now).We should certainly be doing a ptwr_flush() before switching page table modes. My recollection is that domain_pause in shadow_enable would cause a sync_pagetable_state, but that code has changed a lot since I wrote it. Ian> So I think the current state in the writeable page should be > flushed and adjusted (in audit, for example, make the > write-protected pages back to > writeable) before we switch to shadow mode. Given the fact > that we can switch writeable pagetable to shadow log-dirty at > runtime for the plain 32-bit, I''m wondering where we are > doing that kind of thing. > > Jun > --- > Intel Open Source Technology Center > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xensource.com > http://lists.xensource.com/xen-devel >_______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel