linux-kernel - [PATCH 22/40] KVM: SVM: add module parameter to disable Nested Paging

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Message-Id: <1206974244-9716-23-git-send-email-avi@qumranet.com>
Date:	Mon, 31 Mar 2008 17:37:06 +0300
From:	Avi Kivity <avi@...ranet.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org, Joerg Roedel <joerg.roedel@....com>
Subject: [PATCH 22/40] KVM: SVM: add module parameter to disable Nested Paging

From: Joerg Roedel <joerg.roedel@....com>

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@....com>
Signed-off-by: Avi Kivity <avi@...ranet.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 c12a759..fb5d6c2 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 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");
 
-- 
1.5.4.5

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