[PATCH 3/8] 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=off to the kvm_amd module.

Signed-off-by: Joerg Roedel <joerg.roedel@xxxxxxx>
---
arch/x86/kvm/svm.c | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 49bb57a..2e718ff 100644
--- 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 char *npt = "on";
+
+module_param(npt, charp, S_IRUGO);

static void kvm_reput_irq(struct vcpu_svm *svm);

@@ -415,6 +418,11 @@ static __init int svm_hardware_setup(void)
if (!svm_has(SVM_FEATURE_NPT))
npt_enabled = false;

+ if (npt_enabled && strncmp(npt, "off", 3) == 0) {
+ printk(KERN_INFO "kvm: Nested Paging disabled\n");
+ npt_enabled = false;
+ }
+
if (npt_enabled)
printk(KERN_INFO "kvm: Nested Paging enabled\n");

--
1.5.3.7



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