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

[Avi Kivity <avi@qumranet.com>]

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@qumranet.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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