linux-kernel - [PATCH 3/8] SVM: add module parameter to disable Nested Paging

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Message-ID: <1201294393-22613-4-git-send-email-joerg.roedel@amd.com>
Date:	Fri, 25 Jan 2008 21:53:08 +0100
From:	"Joerg Roedel" <joerg.roedel@....com>
To:	"Avi Kivity" <avi@...ranet.com>, kvm-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org
cc:	"Joerg Roedel" <joerg.roedel@....com>
Subject: [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@....com>
---
 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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