[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@qumranet.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/kvm/vmx.c b/drivers/kvm/vmx.c
index 27f2751c3baa66e404631f37c5ddb7ed15ebc23f..54c35c0b31815670dd56cbc54b18826e1ea6f80d 100644 (file)
--- a/drivers/kvm/vmx.c
+++ b/drivers/kvm/vmx.c
@@ -1116,6 +1116,8 @@ static int vmx_vcpu_setup(struct kvm_vcpu *vcpu)
 
                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;