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KVM: VMX: Atomically switch efer if EPT && !EFER.NX

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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@redhat.com>
This commit is contained in:
Avi Kivity 2010-04-28 16:42:29 +03:00
parent 61d2ef2ce3
commit 84ad33ef5d
1 changed files with 12 additions and 0 deletions
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12
arch/x86/kvm/vmx.c
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@ -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;
}
@ -1734,6 +1745,7 @@ static void exit_lmode(struct kvm_vcpu *vcpu)
vmcs_write32(VM_ENTRY_CONTROLS,
vmcs_read32(VM_ENTRY_CONTROLS)
& ~VM_ENTRY_IA32E_MODE);
vmx_set_efer(vcpu, vcpu->arch.efer);
}
#endif