On Tue, Jul 22, 2014 at 05:55:20AM +0800, Xiao Guangrong wrote:
>
> On Jul 10, 2014, at 3:12 AM, mtosatti@xxxxxxxxxx wrote:
>
> > Reload remote vcpus MMU from GET_DIRTY_LOG codepath, before
> > deleting a pinned spte.
> >
> > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> >
> > ---
> > 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;
> > + } else
> > + mmu_reload_pinned_vcpus(kvm);
> > + }
> > +
> > +
> > if (pt_protect)
> > spte &= ~SPTE_MMU_WRITEABLE;
> > spte = spte & ~PT_WRITABLE_MASK;
>
> This is also a window between marking spte readonly and re-ping…
> IIUC, I think all spte spte can not be zapped and write-protected at any time
It is safe because mmu_lock is held by kvm_mmu_slot_remove_write_access
?
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