Revert "x86/kvm: Toggle IBRS on VM entry and exit"

CVE-2017-5753 (revert embargoed)
CVE-2017-5715 (revert embargoed)

This reverts commit e233ec08.
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/kvm/vmx.c

@@ -8599,11 +8599,6 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
 		vmx_set_interrupt_shadow(vcpu, 0);
 
 	atomic_switch_perf_msrs(vmx);
-
-	if (boot_cpu_has(X86_FEATURE_SPEC_CTRL))
-		add_atomic_switch_msr(vmx, MSR_IA32_SPEC_CTRL,
-			vcpu->arch.spec_ctrl, FEATURE_ENABLE_IBRS);
-
 	debugctlmsr = get_debugctlmsr();
 
 	vmx->__launched = vmx->loaded_vmcs->launched;