Commit 2d5d3fc5 authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: VMX: introduce module parameter to disable CET 

There have been reports of host hangs caused by CET virtualization.
Until these are analyzed further, introduce a module parameter that
makes it possible to easily disable it.

Link: https://lore.kernel.org/all/85548beb-1486-40f9-beb4-632c78e3360b@proxmox.com/


Cc: David Riley <d.riley@proxmox.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent ef7e0c51

arch/x86/kvm/vmx/capabilities.h

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ extern bool __read_mostly flexpriority_enabled; 
extern bool __read_mostly enable_ept;

extern bool __read_mostly enable_unrestricted_guest;

extern bool __read_mostly enable_ept_ad_bits;

extern bool __read_mostly enable_cet;

extern bool __read_mostly enable_pml;

extern int __read_mostly pt_mode;

arch/x86/kvm/vmx/vmx.c

+15 −2
Original line number Diff line number Diff line
@@ -108,6 +108,9 @@ module_param_named(unrestricted_guest, 
bool __read_mostly enable_ept_ad_bits = 1;

module_param_named(eptad, enable_ept_ad_bits, bool, 0444);



bool __read_mostly enable_cet = 1;

module_param_named(cet, enable_cet, bool, 0444);



static bool __read_mostly emulate_invalid_guest_state = true;

module_param(emulate_invalid_guest_state, bool, 0444);
@@ -4476,7 +4479,7 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx) 
	 * SSP is reloaded from IA32_PL3_SSP. Check SDM Vol.2A/B Chapter

	 * 3 and 4 for details.

	 */

	if (cpu_has_load_cet_ctrl()) {

	if (enable_cet) {

		vmcs_writel(HOST_S_CET, kvm_host.s_cet);

		vmcs_writel(HOST_SSP, 0);

		vmcs_writel(HOST_INTR_SSP_TABLE, 0);
@@ -4532,6 +4535,10 @@ static u32 vmx_get_initial_vmentry_ctrl(void) 
	if (vmx_pt_mode_is_system())

		vmentry_ctrl &= ~(VM_ENTRY_PT_CONCEAL_PIP |

				  VM_ENTRY_LOAD_IA32_RTIT_CTL);



	if (!enable_cet)

		vmentry_ctrl &= ~VM_ENTRY_LOAD_CET_STATE;



	/*

	 * IA32e mode, and loading of EFER and PERF_GLOBAL_CTRL are toggled dynamically.

	 */
@@ -4546,6 +4553,9 @@ static u32 vmx_get_initial_vmexit_ctrl(void) 
{

	u32 vmexit_ctrl = vmcs_config.vmexit_ctrl;



	if (!enable_cet)

		vmexit_ctrl &= ~VM_EXIT_LOAD_CET_STATE;



	/*

	 * Not used by KVM and never set in vmcs01 or vmcs02, but emulated for

	 * nested virtualization and thus allowed to be set in vmcs12.
@@ -8155,7 +8165,7 @@ static __init void vmx_set_cpu_caps(void) 
	 * VMX_BASIC[bit56] == 0, inject #CP at VMX entry with error code

	 * fails, so disable CET in this case too.

	 */

	if (!cpu_has_load_cet_ctrl() || !enable_unrestricted_guest ||

	if (!enable_cet || !enable_unrestricted_guest ||

	    !cpu_has_vmx_basic_no_hw_errcode_cc()) {

		kvm_cpu_cap_clear(X86_FEATURE_SHSTK);

		kvm_cpu_cap_clear(X86_FEATURE_IBT);
@@ -8630,6 +8640,9 @@ __init int vmx_hardware_setup(void) 
	    !cpu_has_vmx_invept_global())

		enable_ept = 0;



	if (!cpu_has_load_cet_ctrl())

		enable_cet = 0;



	/* NX support is required for shadow paging. */

	if (!enable_ept && !boot_cpu_has(X86_FEATURE_NX)) {

		pr_err_ratelimited("NX (Execute Disable) not supported\n");