On Wed, Oct 08, 2014 at 09:56:36AM +0300, Gleb Natapov wrote: > On Mon, Oct 06, 2014 at 02:19:32PM -0300, Marcelo Tosatti wrote: > > On Sat, Oct 04, 2014 at 10:23:32AM +0300, Gleb Natapov wrote: > > > On Tue, Sep 09, 2014 at 12:28:11PM -0300, Marcelo Tosatti wrote: > > > > On Mon, Jul 21, 2014 at 04:14:24PM +0300, Gleb Natapov wrote: > > > > > On Wed, Jul 09, 2014 at 04:12:53PM -0300, [email protected] wrote: > > > > > > Reload remote vcpus MMU from GET_DIRTY_LOG codepath, before > > > > > > deleting a pinned spte. > > > > > > > > > > > > Signed-off-by: Marcelo Tosatti <[email protected]> > > > > > > > > > > > > --- > > > > > > arch/x86/kvm/mmu.c | 29 +++++++++++++++++++++++------ > > > > > > 1 file changed, 23 insertions(+), 6 deletions(-) > > > > > > > > > > > > Index: kvm.pinned-sptes/arch/x86/kvm/mmu.c > > > > > > =================================================================== > > > > > > --- kvm.pinned-sptes.orig/arch/x86/kvm/mmu.c 2014-07-09 > > > > > > 11:23:59.290744490 -0300 > > > > > > +++ kvm.pinned-sptes/arch/x86/kvm/mmu.c 2014-07-09 > > > > > > 11:24:58.449632435 -0300 > > > > > > @@ -1208,7 +1208,8 @@ > > > > > > * > > > > > > * Return true if tlb need be flushed. > > > > > > */ > > > > > > -static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool > > > > > > pt_protect) > > > > > > +static bool spte_write_protect(struct kvm *kvm, u64 *sptep, bool > > > > > > pt_protect, > > > > > > + bool skip_pinned) > > > > > > { > > > > > > u64 spte = *sptep; > > > > > > > > > > > > @@ -1218,6 +1219,22 @@ > > > > > > > > > > > > rmap_printk("rmap_write_protect: spte %p %llx\n", sptep, > > > > > > *sptep); > > > > > > > > > > > > + if (is_pinned_spte(spte)) { > > > > > > + /* keep pinned spte intact, mark page dirty again */ > > > > > > + if (skip_pinned) { > > > > > > + struct kvm_mmu_page *sp; > > > > > > + gfn_t gfn; > > > > > > + > > > > > > + sp = page_header(__pa(sptep)); > > > > > > + gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt); > > > > > > + > > > > > > + mark_page_dirty(kvm, gfn); > > > > > > + return false; > > > > > Why not mark all pinned gfns as dirty in kvm_vm_ioctl_get_dirty_log() > > > > > while > > > > > populating dirty_bitmap_buffer? > > > > > > > > The pinned gfns are per-vcpu. Requires looping all vcpus (not > > > > scalable). > > > > > > > OK, but do they really have to be per-cpu? What's the advantage? > > > > The guest configures pinning on a per-cpu basis (that is, enabling PEBS > > is done on a per-cpu basis). > Is it a problem to maintain global pinned pages list for each memslot too? > > > > > > > > > > > > > + } else > > > > > > + mmu_reload_pinned_vcpus(kvm); > > > > > Can you explain why do you need this? > > > > > > > > Because if skip_pinned = false, we want vcpus to exit (called > > > > from enable dirty logging codepath). > > > > > > > I guess what I wanted to ask is why do we need skip_pinned? As far as I > > > see it > > > is set to false in two cases: > > > 1: page is write protected for shadow MMU needs, should not happen since > > > the feature > > > > Correct. > > > > > is not supported with shadow mmu (can happen with nested EPT, but page > > > will be marked > > > is accessed during next vcpu entry anyway, so how will it work)? > > > > PEBS is not supported on nested EPT. > > > OK, so for this case we do not need skip_pinned. Assert if it happens. > > > > 2: when slot is marked as read only: such slot cannot have PEBS pages and > > > if it will guest will die > > > anyway during next guest entry, so why not maintain list of pinned > > > pages per slot and kill aguest > > > if slot with pinned pages is marked read only. > > > > 2: when slots pages have dirty logging enabled. In that case, the page > > is marked dirty immediately. This is the call from > > kvm_mmu_slot_remove_write_access. > > > Right, my 2 is incorrect. > > > So when enabling dirty logging, for pinned sptes: > > > > - maintain pinned spte intact. > > - mark gfn for which pinned spte represents as dirty in the dirty > > log. > > > But you set skip_pinned to false in kvm_mmu_slot_remove_write_access(), so > this is not > what is happening. Did you mean to set it to true there?
Argh, lets try again: skip_pinned = true ------------------ mark page dirty, keep spte intact called from get dirty log path. skip_pinned = false ------------------- reload remote mmu destroy pinned spte. called from: dirty log enablement, rmap write protect (unused for pinned sptes) Note this behaviour is your suggestion: > > > > Why write protect it at all? mmu_reload_pinned_vcpus() will > > > > unprotected > > > > it anyway > > > > on the next vmentry. Isn't it better to just report all pinned > > > > pages as > > > > dirty alway. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
