[PATCH 2/5] KVM: MMU: split the operations of kvm_mmu_zap_page()

[Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>]

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

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxx>
---
 arch/x86/include/asm/kvm_host.h |    1 +
 arch/x86/kvm/mmu.c              |   42 ++++++++++++++++++++++++++++++++++++++-
 arch/x86/kvm/x86.c              |    1 +
 3 files changed, 43 insertions(+), 1 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 0cd0f29..e4df1cf 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -388,6 +388,7 @@ struct kvm_arch {
 	 * Hash table of struct kvm_mmu_page.
 	 */
 	struct list_head active_mmu_pages;
+	struct list_head invalid_mmu_pages;
 	struct list_head assigned_dev_head;
 	struct iommu_domain *iommu_domain;
 	int iommu_flags;
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 84c705e..0c957bf 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -915,6 +915,7 @@ 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)
@@ -1560,6 +1561,46 @@ static int mmu_zap_unsync_children(struct kvm *kvm,
 	return zapped;
 }
 
+static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+	int ret;
+
+	trace_kvm_mmu_zap_page(sp);
+	++kvm->stat.mmu_shadow_zapped;
+	ret = mmu_zap_unsync_children(kvm, sp);
+	kvm_mmu_page_unlink_children(kvm, sp);
+	kvm_mmu_unlink_parents(kvm, sp);
+	if (!sp->role.invalid && !sp->role.direct)
+		unaccount_shadowed(kvm, sp->gfn);
+	if (sp->unsync)
+		kvm_unlink_unsync_page(kvm, sp);
+	if (!sp->root_count)
+		/* Count self */
+		ret++;
+	else
+		kvm_reload_remote_mmus(kvm);
+
+	sp->role.invalid = 1;
+	list_move(&sp->link, &kvm->arch.invalid_mmu_pages);
+	kvm_mmu_reset_last_pte_updated(kvm);
+	return ret;
+}
+
+static void kvm_mmu_commit_zap_page(struct kvm *kvm)
+{
+	struct kvm_mmu_page *sp, *n;
+
+	if (list_empty(&kvm->arch.invalid_mmu_pages))
+		return;
+
+	kvm_flush_remote_tlbs(kvm);
+	list_for_each_entry_safe(sp, n, &kvm->arch.invalid_mmu_pages, link) {
+		WARN_ON(!sp->role.invalid);
+		if (!sp->root_count)
+			kvm_mmu_free_page(kvm, sp);
+	}
+}
+
 static int kvm_mmu_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 {
 	int ret;
@@ -1577,7 +1618,6 @@ 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);
 	} else {
 		sp->role.invalid = 1;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5e5cd8d..225c3c4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5331,6 +5331,7 @@ struct  kvm *kvm_arch_create_vm(void)
 	}
 
 	INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
+	INIT_LIST_HEAD(&kvm->arch.invalid_mmu_pages);
 	INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
 
 	/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */
-- 
1.6.1.2



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