On Mon, Jul 30, 2012 at 10:49 PM, Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> wrote: > On 07/31/2012 01:18 AM, Sunil wrote: >> Hello List, >> >> I am a KVM newbie and studying KVM mmu code. >> >> On the existing guest, I am trying to track all guest writes by >> marking page table entry as read-only in EPT entry [ I am using Intel >> machine with vmx and ept support ]. Looks like EPT support re-uses >> shadow page table(SPT) code and hence some of SPT routines. >> >> I was thinking of below possible approach. Use pte_list_walk() to >> traverse through list of sptes and use mmu_spte_update() to flip the >> PT_WRITABLE_MASK flag. But all SPTEs are not part of any single list; >> but on separate lists (based on gfn, page level, memory_slot). So, >> recording all the faulted guest GFN and then using above method work ? >> > > There are two ways to write-protect all sptes: > - use kvm_mmu_slot_remove_write_access() on all memslots > - walk the shadow page cache to get the shadow pages in the highest level > (level = 4 on EPT), then write-protect its entries. > > If you just want to do it for the specified gfn, you can use > rmap_write_protect(). > > Just inquisitive, what is your purpose? :) > Thanks Xiao ! Just hands on with virtualization hardware. Trying to preserve guest state after migration. -- Sunl -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
