3 files changed, 20 insertions, 1 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 6651dfadae50..21cfa289d0fe 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -32,6 +32,15 @@
 #include <asm/cmpxchg.h>
 #include <asm/io.h>
 
+/*
+ * When setting this variable to true it enables Two-Dimensional-Paging
+ * where the hardware walks 2 page tables:
+ * 1. the guest-virtual to guest-physical
+ * 2. while doing 1. it walks guest-physical to host-physical
+ * If the hardware supports that we don't need to do shadow paging.
+ */
+static bool tdp_enabled = false;
+
 #undef MMU_DEBUG
 
 #undef AUDIT
@@ -1582,6 +1591,12 @@ out:
 }
 EXPORT_SYMBOL_GPL(kvm_mmu_page_fault);
 
+void kvm_enable_tdp(void)
+{
+        tdp_enabled = true;
+}
+EXPORT_SYMBOL_GPL(kvm_enable_tdp);
+
 static void free_mmu_pages(struct kvm_vcpu *vcpu)
 {
         struct kvm_mmu_page *sp;
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index fb5d6c2e6a08..9e29a13136c4 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -426,8 +426,10 @@ static __init int svm_hardware_setup(void)
                 npt_enabled = false;
         }
 
-        if (npt_enabled)
+        if (npt_enabled) {
                 printk(KERN_INFO "kvm: Nested Paging enabled\n");
+                kvm_enable_tdp();
+        }
 
         return 0;
 
diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 274f153c8704..5c6ba2212b1b 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -493,6 +493,8 @@ int kvm_fix_hypercall(struct kvm_vcpu *vcpu);
 
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t gva, u32 error_code);
 
+void kvm_enable_tdp(void);
+
 int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
 int complete_pio(struct kvm_vcpu *vcpu);