Il 22/09/2014 23:54, Andres Lagar-Cavilla ha scritto:
> @@ -1406,32 +1406,24 @@ static int kvm_age_rmapp(struct kvm *kvm, unsigned long *rmapp,
> struct rmap_iterator uninitialized_var(iter);
> int young = 0;
>
> - /*
> - * In case of absence of EPT Access and Dirty Bits supports,
> - * emulate the accessed bit for EPT, by checking if this page has
> - * an EPT mapping, and clearing it if it does. On the next access,
> - * a new EPT mapping will be established.
> - * This has some overhead, but not as much as the cost of swapping
> - * out actively used pages or breaking up actively used hugepages.
> - */
> - if (!shadow_accessed_mask) {
> - young = kvm_unmap_rmapp(kvm, rmapp, slot, data);
> - goto out;
> - }
> + BUG_ON(!shadow_accessed_mask);
>
> for (sptep = rmap_get_first(*rmapp, &iter); sptep;
> sptep = rmap_get_next(&iter)) {
> + struct kvm_mmu_page *sp;
> + gfn_t gfn;
> BUG_ON(!is_shadow_present_pte(*sptep));
> + /* From spte to gfn. */
> + sp = page_header(__pa(sptep));
> + gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
>
> if (*sptep & shadow_accessed_mask) {
> young = 1;
> clear_bit((ffs(shadow_accessed_mask) - 1),
> (unsigned long *)sptep);
> }
> + trace_kvm_age_page(gfn, slot, young);
Yesterday I couldn't think of a way to avoid the
page_header/kvm_mmu_page_get_gfn on every iteration, but it's actually
not hard. Instead of passing hva as datum, you can pass (unsigned long)
&start. Then you can add PAGE_SIZE to it at the end of every call to
kvm_age_rmapp, and keep the old tracing logic.
Paolo
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