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From: Lai Jiangshan on 17 Apr 2010 05:00

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(a)cn.fujitsu.com>
---
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,

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