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Commit 84ad33ef authored by Avi Kivity's avatar Avi Kivity
Browse files

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



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: default avatarAvi Kivity <avi@redhat.com>
parent 61d2ef2c

arch/x86/kvm/vmx.c

+12 −0
Original line number Diff line number Diff line
@@ -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