On Sun, Nov 21, 2021 at 9:05 PM Nikunj A. Dadhania <nikunj@xxxxxxx> wrote:
>
>
>
> On 11/20/2021 5:27 AM, David Matlack wrote:
> > When dirty logging is enabled without initially-all-set, attempt to
> > split all large pages in the memslot down to 4KB pages so that vCPUs
> > do not have to take expensive write-protection faults to split large
> > pages.
> >
> > Large page splitting is best-effort only. This commit only adds the
> > support for the TDP MMU, and even there splitting may fail due to out
> > of memory conditions. Failures to split a large page is fine from a
> > correctness standpoint because we still always follow it up by write-
> > protecting any remaining large pages.
> >
> > Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
>
> > +int mmu_topup_split_caches(struct kvm *kvm)
> > +{
> > + struct kvm_mmu_memory_caches *split_caches = &kvm->arch.split_caches;
> > + int r;
> > +
> > + assert_split_caches_invariants(kvm);
> > +
> > + r = kvm_mmu_topup_memory_cache(&split_caches->page_header_cache, 1);
> > + if (r)
> > + goto out;
> > +
> > + r = kvm_mmu_topup_memory_cache(&split_caches->shadow_page_cache, 1);
> > + if (r)
> > + goto out;
> > +
> > + return 0;
> > +
> > +out:
> > + pr_warn("Failed to top-up split caches. Will not split large pages.\n");
> > + return r;
> > +}
> > +
> > +static void mmu_free_split_caches(struct kvm *kvm)
> > +{
> > + assert_split_caches_invariants(kvm);
> > +
> > + kvm_mmu_free_memory_cache(&kvm->arch.split_caches.pte_list_desc_cache);
> ^^^^^^^^^^^^^^
> I believe this should be page_header_cache.
Oh wow, thanks for catching that. You are correct. Will fix in v1.
>
> > + kvm_mmu_free_memory_cache(&kvm->arch.split_caches.shadow_page_cache);
> > +}
>
> Regards
> Nikunj
>
