Re: [PATCH 2/4] KVM: MMU: support unsync sp out of the protection of 'mmu_lock'

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 On 09/20/2010 04:19 PM, Xiao Guangrong wrote:
It allows keep unsync sp alive while it's out of the protection, later we can use
kvm_mmu_free_page() to free it if !sp->active_count

Don't understand.  Of course unsync pages exist outside mmu_lock...?


diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 839852d..4b7af3f 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -996,7 +996,6 @@ 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)
  		__free_page(virt_to_page(sp->gfns));
@@ -1681,9 +1680,8 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *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->active_count) {
+
+	if (!sp->active_count || sp->unsync) {
  		/* Count self */
  		ret++;
  		list_move(&sp->link, invalid_list);

How can you drop an active unsync page?

I'm missing something here.

@@ -1692,6 +1690,8 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
  		kvm_reload_remote_mmus(kvm);
  	}

+	if (sp->unsync)
+		kvm_unlink_unsync_page(kvm, sp);
  	sp->role.invalid = 1;
  	kvm_mmu_reset_last_pte_updated(kvm);
  	return ret;
@@ -1709,8 +1709,12 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,

  	do {
  		sp = list_first_entry(invalid_list, struct kvm_mmu_page, link);
-		WARN_ON(!sp->role.invalid || sp->active_count);
-		kvm_mmu_free_page(kvm, sp);
+		WARN_ON(!sp->role.invalid);
+		list_del(&sp->link);
+		if (sp->active_count)
+			WARN_ON(!sp->unsync);
+		else
+			kvm_mmu_free_page(kvm, sp);
  	} while (!list_empty(invalid_list));

  }


--
error compiling committee.c: too many arguments to function

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