KVM: SVM: allow enabling/disabling NPT by reloading only the architecture module

If NPT is enabled after loading both KVM modules on AMD and it should be
disabled, both KVM modules must be reloaded. If only the architecture module is
reloaded the behavior is undefined. With this patch it is possible to disable
NPT only by reloading the kvm_amd module.

Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

2 files changed, 8 insertions, 1 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index b0e4ddca6c18..d087d9c4f2d9 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1870,6 +1870,12 @@ void kvm_enable_tdp(void)
 }
 EXPORT_SYMBOL_GPL(kvm_enable_tdp);
 
+void kvm_disable_tdp(void)
+{
+        tdp_enabled = false;
+}
+EXPORT_SYMBOL_GPL(kvm_disable_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 b756e876dce3..951b789cc913 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -453,7 +453,8 @@ static __init int svm_hardware_setup(void)
         if (npt_enabled) {
                 printk(KERN_INFO "kvm: Nested Paging enabled\n");
                 kvm_enable_tdp();
-        }
+        } else
+                kvm_disable_tdp();
 
         return 0;