Commit 7775834a authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Avi Kivity
Browse files

KVM: MMU: split the operations of kvm_mmu_zap_page() 



Using kvm_mmu_prepare_zap_page() and kvm_mmu_commit_zap_page() to
split kvm_mmu_zap_page() function, then we can:

- traverse hlist safely
- easily to gather remote tlb flush which occurs during page zapped

Those feature can be used in the later patches

Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 7ae680eb

arch/x86/kvm/mmu.c

+43 −9
Original line number Diff line number Diff line
@@ -916,6 +916,7 @@ static int is_empty_shadow_page(u64 *spt) 
static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)

{

	ASSERT(is_empty_shadow_page(sp->spt));

	hlist_del(&sp->hash_link);

	list_del(&sp->link);

	__free_page(virt_to_page(sp->spt));

	if (!sp->role.direct)
@@ -1200,6 +1201,10 @@ static void kvm_unlink_unsync_page(struct kvm *kvm, struct kvm_mmu_page *sp) 
}



static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp);

static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,

				    struct list_head *invalid_list);

static void kvm_mmu_commit_zap_page(struct kvm *kvm,

				    struct list_head *invalid_list);



#define for_each_gfn_sp(kvm, sp, gfn, pos, n)				\

  hlist_for_each_entry_safe(sp, pos, n,					\
@@ -1530,7 +1535,8 @@ static void kvm_mmu_unlink_parents(struct kvm *kvm, struct kvm_mmu_page *sp) 
}



static int mmu_zap_unsync_children(struct kvm *kvm,

				   struct kvm_mmu_page *parent)

				   struct kvm_mmu_page *parent,

				   struct list_head *invalid_list)

{

	int i, zapped = 0;

	struct mmu_page_path parents;
@@ -1544,7 +1550,7 @@ static int mmu_zap_unsync_children(struct kvm *kvm, 
		struct kvm_mmu_page *sp;



		for_each_sp(pages, sp, parents, i) {

			kvm_mmu_zap_page(kvm, sp);

			kvm_mmu_prepare_zap_page(kvm, sp, invalid_list);

			mmu_pages_clear_parents(&parents);

			zapped++;

		}
@@ -1554,16 +1560,16 @@ static int mmu_zap_unsync_children(struct kvm *kvm, 
	return zapped;

}



static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)

static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,

				    struct list_head *invalid_list)

{

	int ret;



	trace_kvm_mmu_zap_page(sp);

	trace_kvm_mmu_prepare_zap_page(sp);

	++kvm->stat.mmu_shadow_zapped;

	ret = mmu_zap_unsync_children(kvm, sp);

	ret = mmu_zap_unsync_children(kvm, sp, invalid_list);

	kvm_mmu_page_unlink_children(kvm, sp);

	kvm_mmu_unlink_parents(kvm, sp);

	kvm_flush_remote_tlbs(kvm);

	if (!sp->role.invalid && !sp->role.direct)

		unaccount_shadowed(kvm, sp->gfn);

	if (sp->unsync)
@@ -1571,17 +1577,45 @@ static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp) 
	if (!sp->root_count) {

		/* Count self */

		ret++;

		hlist_del(&sp->hash_link);

		kvm_mmu_free_page(kvm, sp);

		list_move(&sp->link, invalid_list);

	} else {

		sp->role.invalid = 1;

		list_move(&sp->link, &kvm->arch.active_mmu_pages);

		kvm_reload_remote_mmus(kvm);

	}



	sp->role.invalid = 1;

	kvm_mmu_reset_last_pte_updated(kvm);

	return ret;

}



static void kvm_mmu_commit_zap_page(struct kvm *kvm,

				    struct list_head *invalid_list)

{

	struct kvm_mmu_page *sp;



	if (list_empty(invalid_list))

		return;



	kvm_flush_remote_tlbs(kvm);



	do {

		sp = list_first_entry(invalid_list, struct kvm_mmu_page, link);

		WARN_ON(!sp->role.invalid || sp->root_count);

		kvm_mmu_free_page(kvm, sp);

	} while (!list_empty(invalid_list));



}



static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)

{

	LIST_HEAD(invalid_list);

	int ret;



	ret = kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);

	kvm_mmu_commit_zap_page(kvm, &invalid_list);

	return ret;

}



/*

 * Changing the number of mmu pages allocated to the vm

 * Note: if kvm_nr_mmu_pages is too small, you will get dead lock

arch/x86/kvm/mmutrace.h

+1 −1
Original line number Diff line number Diff line
@@ -190,7 +190,7 @@ DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_unsync_page, 
	TP_ARGS(sp)

);



DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_zap_page,

DEFINE_EVENT(kvm_mmu_page_class, kvm_mmu_prepare_zap_page,

	TP_PROTO(struct kvm_mmu_page *sp),



	TP_ARGS(sp)