KVM: SVM: add module parameter to disable Nested Paging

To disable the use of the Nested Paging feature even if it is available in
hardware this patch adds a module parameter. Nested Paging can be disabled by
passing npt=0 to the kvm_amd module.

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

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index c12a75953b5bf4cfdd17f1f6d071fd07518018a3..fb5d6c2e6a08043e5062e89c6bc9dccbcfc19bff 100644 (file)
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -48,6 +48,9 @@ MODULE_LICENSE("GPL");
 #define SVM_DEATURE_SVML (1 << 2)
 
 static bool npt_enabled = false;
+static int npt = 1;
+
+module_param(npt, int, S_IRUGO);
 
 static void kvm_reput_irq(struct vcpu_svm *svm);
 
@@ -418,6 +421,11 @@ static __init int svm_hardware_setup(void)
        if (!svm_has(SVM_FEATURE_NPT))
                npt_enabled = false;
 
+       if (npt_enabled && !npt) {
+               printk(KERN_INFO "kvm: Nested Paging disabled\n");
+               npt_enabled = false;
+       }
+
        if (npt_enabled)
                printk(KERN_INFO "kvm: Nested Paging enabled\n");