When EPT is enabled, we cannot emulate EFER.NX=0 through the shadow page
tables. This causes accesses through ptes with bit 63 set to succeed instead
of failing a reserved bit check.
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index ae22dcf..cc78fee 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -678,6 +678,17 @@ static bool update_transition_efer(struct vcpu_vmx *vmx, int efer_offset)
guest_efer |= host_efer & ignore_bits;
vmx->guest_msrs[efer_offset].data = guest_efer;
vmx->guest_msrs[efer_offset].mask = ~ignore_bits;
+
+ clear_atomic_switch_msr(vmx, MSR_EFER);
+ /* On ept, can't emulate nx, and must switch nx atomically */
+ if (enable_ept && ((vmx->vcpu.arch.efer ^ host_efer) & EFER_NX)) {
+ guest_efer = vmx->vcpu.arch.efer;
+ if (!(guest_efer & EFER_LMA))
+ guest_efer &= ~EFER_LME;
+ add_atomic_switch_msr(vmx, MSR_EFER, guest_efer, host_efer);
+ return false;
+ }
+
return true;
}
--
1.7.0.4
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