kvm: vmx: Allow disabling virtual NMI support

To simplify testing of these rarely used code paths, add a module parameter
that turns it on.  One eventinj.flat test (NMI after iret) fails when
loading kvm_intel with vnmi=0.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index bfee7f4ac1dd7f8ab65e1e583af90d48fab5338d..714a0673ec3cb2153dce2f192f412fc14e0d19df 100644 (file)
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -70,6 +70,9 @@ MODULE_DEVICE_TABLE(x86cpu, vmx_cpu_id);
 static bool __read_mostly enable_vpid = 1;
 module_param_named(vpid, enable_vpid, bool, 0444);
 
+static bool __read_mostly enable_vnmi = 1;
+module_param_named(vnmi, enable_vnmi, bool, S_IRUGO);
+
 static bool __read_mostly flexpriority_enabled = 1;
 module_param_named(flexpriority, flexpriority_enabled, bool, S_IRUGO);
 
@@ -5236,6 +5239,10 @@ static u32 vmx_pin_based_exec_ctrl(struct vcpu_vmx *vmx)
 
        if (!kvm_vcpu_apicv_active(&vmx->vcpu))
                pin_based_exec_ctrl &= ~PIN_BASED_POSTED_INTR;
+
+       if (!enable_vnmi)
+               pin_based_exec_ctrl &= ~PIN_BASED_VIRTUAL_NMIS;
+
        /* Enable the preemption timer dynamically */
        pin_based_exec_ctrl &= ~PIN_BASED_VMX_PREEMPTION_TIMER;
        return pin_based_exec_ctrl;
@@ -5670,7 +5677,7 @@ static void enable_irq_window(struct kvm_vcpu *vcpu)
 
 static void enable_nmi_window(struct kvm_vcpu *vcpu)
 {
-       if (!cpu_has_virtual_nmis() ||
+       if (!enable_vnmi ||
            vmcs_read32(GUEST_INTERRUPTIBILITY_INFO) & GUEST_INTR_STATE_STI) {
                enable_irq_window(vcpu);
                return;
@@ -5711,7 +5718,7 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
-       if (!cpu_has_virtual_nmis()) {
+       if (!enable_vnmi) {
                /*
                 * Tracking the NMI-blocked state in software is built upon
                 * finding the next open IRQ window. This, in turn, depends on
@@ -5742,7 +5749,7 @@ static bool vmx_get_nmi_mask(struct kvm_vcpu *vcpu)
        struct vcpu_vmx *vmx = to_vmx(vcpu);
        bool masked;
 
-       if (!cpu_has_virtual_nmis())
+       if (!enable_vnmi)
                return vmx->loaded_vmcs->soft_vnmi_blocked;
        if (vmx->loaded_vmcs->nmi_known_unmasked)
                return false;
@@ -5755,7 +5762,7 @@ static void vmx_set_nmi_mask(struct kvm_vcpu *vcpu, bool masked)
 {
        struct vcpu_vmx *vmx = to_vmx(vcpu);
 
-       if (!cpu_has_virtual_nmis()) {
+       if (!enable_vnmi) {
                if (vmx->loaded_vmcs->soft_vnmi_blocked != masked) {
                        vmx->loaded_vmcs->soft_vnmi_blocked = masked;
                        vmx->loaded_vmcs->vnmi_blocked_time = 0;
@@ -5776,7 +5783,7 @@ static int vmx_nmi_allowed(struct kvm_vcpu *vcpu)
        if (to_vmx(vcpu)->nested.nested_run_pending)
                return 0;
 
-       if (!cpu_has_virtual_nmis() &&
+       if (!enable_vnmi &&
            to_vmx(vcpu)->loaded_vmcs->soft_vnmi_blocked)
                return 0;
 
@@ -6507,7 +6514,7 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu)
         * AAK134, BY25.
         */
        if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
-                       cpu_has_virtual_nmis() &&
+                       enable_vnmi &&
                        (exit_qualification & INTR_INFO_UNBLOCK_NMI))
                vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO, GUEST_INTR_STATE_NMI);
 
@@ -6567,6 +6574,7 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu)
 
 static int handle_nmi_window(struct kvm_vcpu *vcpu)
 {
+       WARN_ON_ONCE(!enable_vnmi);
        vmcs_clear_bits(CPU_BASED_VM_EXEC_CONTROL,
                        CPU_BASED_VIRTUAL_NMI_PENDING);
        ++vcpu->stat.nmi_window_exits;
@@ -6790,6 +6798,9 @@ static __init int hardware_setup(void)
        if (!cpu_has_vmx_flexpriority())
                flexpriority_enabled = 0;
 
+       if (!cpu_has_virtual_nmis())
+               enable_vnmi = 0;
+
        /*
         * set_apic_access_page_addr() is used to reload apic access
         * page upon invalidation.  No need to do anything if not
@@ -8011,7 +8022,7 @@ static int handle_pml_full(struct kvm_vcpu *vcpu)
         * "blocked by NMI" bit has to be set before next VM entry.
         */
        if (!(to_vmx(vcpu)->idt_vectoring_info & VECTORING_INFO_VALID_MASK) &&
-                       cpu_has_virtual_nmis() &&
+                       enable_vnmi &&
                        (exit_qualification & INTR_INFO_UNBLOCK_NMI))
                vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
                                GUEST_INTR_STATE_NMI);
@@ -8856,7 +8867,7 @@ static int vmx_handle_exit(struct kvm_vcpu *vcpu)
                return 0;
        }
 
-       if (unlikely(!cpu_has_virtual_nmis() &&
+       if (unlikely(!enable_vnmi &&
                     vmx->loaded_vmcs->soft_vnmi_blocked)) {
                if (vmx_interrupt_allowed(vcpu)) {
                        vmx->loaded_vmcs->soft_vnmi_blocked = 0;
@@ -9157,7 +9168,7 @@ static void vmx_recover_nmi_blocking(struct vcpu_vmx *vmx)
 
        idtv_info_valid = vmx->idt_vectoring_info & VECTORING_INFO_VALID_MASK;
 
-       if (cpu_has_virtual_nmis()) {
+       if (enable_vnmi) {
                if (vmx->loaded_vmcs->nmi_known_unmasked)
                        return;
                /*
@@ -9306,7 +9317,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
        unsigned long debugctlmsr, cr3, cr4;
 
        /* Record the guest's net vcpu time for enforced NMI injections. */
-       if (unlikely(!cpu_has_virtual_nmis() &&
+       if (unlikely(!enable_vnmi &&
                     vmx->loaded_vmcs->soft_vnmi_blocked))
                vmx->loaded_vmcs->entry_time = ktime_get();