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
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