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Commit 1047df1f authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: MMU: don't walk every parent pages while mark unsync 



While we mark the parent's unsync_child_bitmap, if the parent is already
unsynced, it no need walk it's parent, it can reduce some unnecessary
workload

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
parent 7a8f1a74

arch/x86/kvm/mmu.c

+17 −44
Original line number Diff line number Diff line
@@ -175,7 +175,7 @@ struct kvm_shadow_walk_iterator { 
	     shadow_walk_okay(&(_walker));			\

	     shadow_walk_next(&(_walker)))



typedef int (*mmu_parent_walk_fn) (struct kvm_mmu_page *sp);

typedef void (*mmu_parent_walk_fn) (struct kvm_mmu_page *sp, u64 *spte);



static struct kmem_cache *pte_chain_cache;

static struct kmem_cache *rmap_desc_cache;
@@ -1024,7 +1024,6 @@ static void mmu_page_remove_parent_pte(struct kvm_mmu_page *sp, 
	BUG();

}





static void mmu_parent_walk(struct kvm_mmu_page *sp, mmu_parent_walk_fn fn)

{

	struct kvm_pte_chain *pte_chain;
@@ -1034,63 +1033,37 @@ static void mmu_parent_walk(struct kvm_mmu_page *sp, mmu_parent_walk_fn fn) 


	if (!sp->multimapped && sp->parent_pte) {

		parent_sp = page_header(__pa(sp->parent_pte));

		fn(parent_sp);

		mmu_parent_walk(parent_sp, fn);

		fn(parent_sp, sp->parent_pte);

		return;

	}



	hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link)

		for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {

			if (!pte_chain->parent_ptes[i])

			u64 *spte = pte_chain->parent_ptes[i];



			if (!spte)

				break;

			parent_sp = page_header(__pa(pte_chain->parent_ptes[i]));

			fn(parent_sp);

			mmu_parent_walk(parent_sp, fn);

			parent_sp = page_header(__pa(spte));

			fn(parent_sp, spte);

		}

}



static void kvm_mmu_update_unsync_bitmap(u64 *spte)

static void mark_unsync(struct kvm_mmu_page *sp, u64 *spte);

static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)

{

	unsigned int index;

	struct kvm_mmu_page *sp = page_header(__pa(spte));



	index = spte - sp->spt;

	if (!__test_and_set_bit(index, sp->unsync_child_bitmap))

		sp->unsync_children++;

	WARN_ON(!sp->unsync_children);

	mmu_parent_walk(sp, mark_unsync);

}



static void kvm_mmu_update_parents_unsync(struct kvm_mmu_page *sp)

static void mark_unsync(struct kvm_mmu_page *sp, u64 *spte)

{

	struct kvm_pte_chain *pte_chain;

	struct hlist_node *node;

	int i;

	unsigned int index;



	if (!sp->parent_pte)

	index = spte - sp->spt;

	if (__test_and_set_bit(index, sp->unsync_child_bitmap))

		return;



	if (!sp->multimapped) {

		kvm_mmu_update_unsync_bitmap(sp->parent_pte);

	if (sp->unsync_children++)

		return;

	}



	hlist_for_each_entry(pte_chain, node, &sp->parent_ptes, link)

		for (i = 0; i < NR_PTE_CHAIN_ENTRIES; ++i) {

			if (!pte_chain->parent_ptes[i])

				break;

			kvm_mmu_update_unsync_bitmap(pte_chain->parent_ptes[i]);

		}

}



static int unsync_walk_fn(struct kvm_mmu_page *sp)

{

	kvm_mmu_update_parents_unsync(sp);

	return 1;

}



static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)

{

	mmu_parent_walk(sp, unsync_walk_fn);

	kvm_mmu_update_parents_unsync(sp);

	kvm_mmu_mark_parents_unsync(sp);

}



static void nonpaging_prefetch_page(struct kvm_vcpu *vcpu,