[patch 3/5] KVM: MMU: add kvm_mmu_shadow_walk helper

[Marcelo Tosatti <mtosatti@redhat.com>]

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Required by EPT misconfiguration handler.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Index: kvm/arch/x86/kvm/mmu.c
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.c
+++ kvm/arch/x86/kvm/mmu.c
@@ -3013,6 +3013,26 @@ out:
 	return r;
 }
 
+void kvm_mmu_shadow_walk(struct kvm_vcpu *vcpu, u64 addr,
+			 struct mmu_shadow_walk *walk)
+{
+	struct kvm_shadow_walk_iterator iterator;
+
+	spin_lock(&vcpu->kvm->mmu_lock);
+	for_each_shadow_entry(vcpu, addr, iterator) {
+		int err;
+
+		err = walk->fn(vcpu, iterator.sptep, iterator.level, walk);
+		if (err)
+			break;
+
+		if (!is_shadow_present_pte(*iterator.sptep))
+			break;
+	}
+	spin_unlock(&vcpu->kvm->mmu_lock);
+}
+EXPORT_SYMBOL(kvm_mmu_shadow_walk);
+
 #ifdef AUDIT
 
 static const char *audit_msg;
Index: kvm/arch/x86/kvm/mmu.h
===================================================================
--- kvm.orig/arch/x86/kvm/mmu.h
+++ kvm/arch/x86/kvm/mmu.h
@@ -37,6 +37,14 @@
 #define PT32_ROOT_LEVEL 2
 #define PT32E_ROOT_LEVEL 3
 
+struct mmu_shadow_walk {
+	int (*fn) (struct kvm_vcpu *vcpu, u64 *sptep, int level,
+		   struct mmu_shadow_walk *walk);
+};
+
+void kvm_mmu_shadow_walk(struct kvm_vcpu *vcpu, u64 addr,
+			 struct mmu_shadow_walk *walk);
+
 static inline void kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
 {
 	if (unlikely(vcpu->kvm->arch.n_free_mmu_pages < KVM_MIN_FREE_MMU_PAGES))