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.
> + kvm_mmu_free_memory_cache(&kvm->arch.split_caches.shadow_page_cache);
> +}
Regards
Nikunj
