On Sat, Apr 17, 2010 at 04:50:13PM +0800, Lai Jiangshan wrote:
>
> mmu_page_remove_parent_pte() does much maintenance works,
> but kvm_mmu_unlink_parents() unlink all parents, so
> such maintenance works are not need.
>
> This patch simplifies the works of kvm_mmu_unlink_parents()
> by unlinking parents without so many maintenance works.
>
> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
> ---
> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
> index 90f666e..71faa04 100644
> --- a/arch/x86/kvm/mmu.c
> +++ b/arch/x86/kvm/mmu.c
> @@ -1453,22 +1453,33 @@ static void kvm_mmu_reset_last_pte_updated(struct kvm *kvm)
>
> static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp)
> {
> - u64 *parent_pte;
> + if (!sp->multimapped) {
> + if (!sp->parent_pte)
> + return;
>
> - while (sp->multimapped || sp->parent_pte) {
> - if (!sp->multimapped)
> - parent_pte = sp->parent_pte;
> - else {
> - struct kvm_pte_chain *chain;
> + __set_spte(sp->parent_pte, shadow_trap_nonpresent_pte);
> + sp->parent_pte = NULL;
> + return;
> + }
>
> - chain = container_of(sp->parent_ptes.first,
> - struct kvm_pte_chain, link);
> - parent_pte = chain->parent_ptes[0];
> + while (!hlist_empty(&sp->parent_ptes)) {
> + struct kvm_pte_chain *chain;
> + u64 *parent_pte;
> + int i;
> +
> + chain = hlist_entry(sp->parent_ptes.first,
> + struct kvm_pte_chain, link);
> + for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {
> + parent_pte = chain->parent_ptes[i];
> + if (!parent_pte)
> + break;
> + __set_spte(parent_pte, shadow_trap_nonpresent_pte);
> }
> - BUG_ON(!parent_pte);
> - kvm_mmu_put_page(sp, parent_pte);
> - __set_spte(parent_pte, shadow_trap_nonpresent_pte);
> + hlist_del(&chain->link);
> + mmu_free_pte_chain(chain);
> }
> + sp->multimapped = 0;
> + sp->parent_pte = NULL;
> }
>
> static int mmu_zap_unsync_children(struct kvm *kvm,
>
Personally i don't see why this is any better than the previous code.
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