On Wed, Dec 22, 2010 at 01:07:23PM +0200, Avi Kivity wrote: > On 12/22/2010 01:01 PM, Marcelo Tosatti wrote: > >If a pagetable contains a writeable large spte, all of its sptes will be > > non-writeable > > >write protected, including non-leaf ones, leading to endless pagefaults. > > > >Do not write protect pages above PT_PAGE_TABLE_LEVEL, as the spte fault > >paths assume non-leaf sptes are writable. > > > >Signed-off-by: Marcelo Tosatti<mtosatti@xxxxxxxxxx> > > > >diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c > >index c3853d5..c716ff8 100644 > >--- a/arch/x86/kvm/mmu.c > >+++ b/arch/x86/kvm/mmu.c > >@@ -3442,6 +3442,9 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot) > > if (!test_bit(slot, sp->slot_bitmap)) > > continue; > > > >+ if (sp->role.level != PT_PAGE_TABLE_LEVEL) > >+ continue; > >+ > > pt = sp->spt; > > for (i = 0; i< PT64_ENT_PER_PAGE; ++i) > > /* avoid RMW */ > > But what about large leaf sptes? Don't we want to write protect, or > perhaps drop them? > > I think write-protecting leaf sptes and ignoring nonleaf sptes should work. When dirty logging is enabled large sptes are nuked and creation of new ones is not allowed. So i don't see the need? -- 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
