linux-kernel - [PATCH] KVM: Fix lockup on 32-bit intel hosts with nx disabled in the bios

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Message-Id: <20070131150017.020B9A0014@il.qumranet.com>
Date:	Wed, 31 Jan 2007 15:00:16 -0000
From:	Avi Kivity <avi@...ranet.com>
To:	kvm-devel@...ts.sourceforge.net
Cc:	linux-kernel@...r.kernel.org, akpm@...l.org, mingo@...e.hu
Subject: [PATCH] KVM: Fix lockup on 32-bit intel hosts with nx disabled in the
	bios

Intel hosts, without long mode, and with nx support disabled in the bios
have an efer that is readable but not writable.  This causes a lockup on
switch to guest mode (even though it should exit with reason 34 according to
the documentation).

Signed-off-by: Avi Kivity <avi@...ranet.com>

Index: linux-2.6/drivers/kvm/vmx.c
===================================================================
--- linux-2.6.orig/drivers/kvm/vmx.c
+++ linux-2.6/drivers/kvm/vmx.c
@@ -1128,6 +1128,8 @@ static int vmx_vcpu_setup(struct kvm_vcp
 
 		if (rdmsr_safe(index, &data_low, &data_high) < 0)
 			continue;
+		if (wrmsr_safe(index, data_low, data_high) < 0)
+			continue;
 		data = data_low | ((u64)data_high << 32);
 		vcpu->host_msrs[j].index = index;
 		vcpu->host_msrs[j].reserved = 0;
-
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