1 files changed, 115 insertions, 59 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index f16a62c79267..2180109d794c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -90,6 +90,11 @@ struct vcpu_vmx {
         } rmode;
         int vpid;
         bool emulation_required;
+
+        /* Support for vnmi-less CPUs */
+        int soft_vnmi_blocked;
+        ktime_t entry_time;
+        s64 vnmi_blocked_time;
 };
 
 static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
@@ -2230,6 +2235,8 @@ static int vmx_vcpu_reset(struct kvm_vcpu *vcpu)
 
         vmx->vcpu.arch.rmode.active = 0;
 
+        vmx->soft_vnmi_blocked = 0;
+
         vmx->vcpu.arch.regs[VCPU_REGS_RDX] = get_rdx_init_val();
         kvm_set_cr8(&vmx->vcpu, 0);
         msr = 0xfee00000 | MSR_IA32_APICBASE_ENABLE;
@@ -2335,6 +2342,29 @@ out:
         return ret;
 }
 
+static void enable_irq_window(struct kvm_vcpu *vcpu)
+{
+        u32 cpu_based_vm_exec_control;
+
+        cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+        cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
+        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
+}
+
+static void enable_nmi_window(struct kvm_vcpu *vcpu)
+{
+        u32 cpu_based_vm_exec_control;
+
+        if (!cpu_has_virtual_nmis()) {
+                enable_irq_window(vcpu);
+                return;
+        }
+
+        cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
+        cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_NMI_PENDING;
+        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
+}
+
 static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -2360,6 +2390,19 @@ static void vmx_inject_nmi(struct kvm_vcpu *vcpu)
 {
         struct vcpu_vmx *vmx = to_vmx(vcpu);
 
+        if (!cpu_has_virtual_nmis()) {
+                /*
+                 * Tracking the NMI-blocked state in software is built upon
+                 * finding the next open IRQ window. This, in turn, depends on
+                 * well-behaving guests: They have to keep IRQs disabled at
+                 * least as long as the NMI handler runs. Otherwise we may
+                 * cause NMI nesting, maybe breaking the guest. But as this is
+                 * highly unlikely, we can live with the residual risk.
+                 */
+                vmx->soft_vnmi_blocked = 1;
+                vmx->vnmi_blocked_time = 0;
+        }
+
         ++vcpu->stat.nmi_injections;
         if (vcpu->arch.rmode.active) {
                 vmx->rmode.irq.pending = true;
@@ -2384,6 +2427,8 @@ static void vmx_update_window_states(struct kvm_vcpu *vcpu)
                 !(guest_intr & (GUEST_INTR_STATE_STI |
                                 GUEST_INTR_STATE_MOV_SS |
                                 GUEST_INTR_STATE_NMI));
+        if (!cpu_has_virtual_nmis() && to_vmx(vcpu)->soft_vnmi_blocked)
+                vcpu->arch.nmi_window_open = 0;
 
         vcpu->arch.interrupt_window_open =
                 ((vmcs_readl(GUEST_RFLAGS) & X86_EFLAGS_IF) &&
@@ -2403,55 +2448,31 @@ static void kvm_do_inject_irq(struct kvm_vcpu *vcpu)
         kvm_queue_interrupt(vcpu, irq);
 }
 
-static void enable_irq_window(struct kvm_vcpu *vcpu)
-{
-        u32 cpu_based_vm_exec_control;
-
-        cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
-        cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_INTR_PENDING;
-        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
-}
-
-static void enable_nmi_window(struct kvm_vcpu *vcpu)
-{
-        u32 cpu_based_vm_exec_control;
-
-        if (!cpu_has_virtual_nmis())
-                return;
-
-        cpu_based_vm_exec_control = vmcs_read32(CPU_BASED_VM_EXEC_CONTROL);
-        cpu_based_vm_exec_control |= CPU_BASED_VIRTUAL_NMI_PENDING;
-        vmcs_write32(CPU_BASED_VM_EXEC_CONTROL, cpu_based_vm_exec_control);
-}
-
 static void do_interrupt_requests(struct kvm_vcpu *vcpu,
                                        struct kvm_run *kvm_run)
 {
         vmx_update_window_states(vcpu);
 
-        if (cpu_has_virtual_nmis()) {
-                if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
-                        if (vcpu->arch.nmi_window_open) {
-                                vcpu->arch.nmi_pending = false;
-                                vcpu->arch.nmi_injected = true;
-                        } else {
-                                enable_nmi_window(vcpu);
-                                return;
-                        }
-                }
-                if (vcpu->arch.nmi_injected) {
-                        vmx_inject_nmi(vcpu);
-                        if (vcpu->arch.nmi_pending
-                            || kvm_run->request_nmi_window)
-                                enable_nmi_window(vcpu);
-                        else if (vcpu->arch.irq_summary
-                                 || kvm_run->request_interrupt_window)
-                                enable_irq_window(vcpu);
+        if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
+                if (vcpu->arch.nmi_window_open) {
+                        vcpu->arch.nmi_pending = false;
+                        vcpu->arch.nmi_injected = true;
+                } else {
+                        enable_nmi_window(vcpu);
                         return;
                 }
-                if (!vcpu->arch.nmi_window_open || kvm_run->request_nmi_window)
+        }
+        if (vcpu->arch.nmi_injected) {
+                vmx_inject_nmi(vcpu);
+                if (vcpu->arch.nmi_pending || kvm_run->request_nmi_window)
                         enable_nmi_window(vcpu);
+                else if (vcpu->arch.irq_summary
+                         || kvm_run->request_interrupt_window)
+                        enable_irq_window(vcpu);
+                return;
         }
+        if (!vcpu->arch.nmi_window_open || kvm_run->request_nmi_window)
+                enable_nmi_window(vcpu);
 
         if (vcpu->arch.interrupt_window_open) {
                 if (vcpu->arch.irq_summary && !vcpu->arch.interrupt.pending)
@@ -3097,6 +3118,37 @@ static int kvm_handle_exit(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
                 printk(KERN_WARNING "%s: unexpected, valid vectoring info "
                        "(0x%x) and exit reason is 0x%x\n",
                        __func__, vectoring_info, exit_reason);
+
+        if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked)) {
+                if (vcpu->arch.interrupt_window_open) {
+                        vmx->soft_vnmi_blocked = 0;
+                        vcpu->arch.nmi_window_open = 1;
+                } else if (vmx->vnmi_blocked_time > 1000000000LL &&
+                    (kvm_run->request_nmi_window || vcpu->arch.nmi_pending)) {
+                        /*
+                         * This CPU don't support us in finding the end of an
+                         * NMI-blocked window if the guest runs with IRQs
+                         * disabled. So we pull the trigger after 1 s of
+                         * futile waiting, but inform the user about this.
+                         */
+                        printk(KERN_WARNING "%s: Breaking out of NMI-blocked "
+                               "state on VCPU %d after 1 s timeout\n",
+                               __func__, vcpu->vcpu_id);
+                        vmx->soft_vnmi_blocked = 0;
+                        vmx->vcpu.arch.nmi_window_open = 1;
+                }
+
+                /*
+                 * If the user space waits to inject an NNI, exit ASAP
+                 */
+                if (vcpu->arch.nmi_window_open && kvm_run->request_nmi_window
+                    && !vcpu->arch.nmi_pending) {
+                        kvm_run->exit_reason = KVM_EXIT_NMI_WINDOW_OPEN;
+                        ++vcpu->stat.nmi_window_exits;
+                        return 0;
+                }
+        }
+
         if (exit_reason < kvm_vmx_max_exit_handlers
             && kvm_vmx_exit_handlers[exit_reason])
                 return kvm_vmx_exit_handlers[exit_reason](vcpu, kvm_run);
@@ -3146,7 +3198,9 @@ static void vmx_complete_interrupts(struct vcpu_vmx *vmx)
                 if (unblock_nmi && vector != DF_VECTOR)
                         vmcs_set_bits(GUEST_INTERRUPTIBILITY_INFO,
                                       GUEST_INTR_STATE_NMI);
-        }
+        } else if (unlikely(vmx->soft_vnmi_blocked))
+                vmx->vnmi_blocked_time +=
+                        ktime_to_ns(ktime_sub(ktime_get(), vmx->entry_time));
 
         idt_vectoring_info = vmx->idt_vectoring_info;
         idtv_info_valid = idt_vectoring_info & VECTORING_INFO_VALID_MASK;
@@ -3186,27 +3240,25 @@ static void vmx_intr_assist(struct kvm_vcpu *vcpu)
 
         vmx_update_window_states(vcpu);
 
-        if (cpu_has_virtual_nmis()) {
-                if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
-                        if (vcpu->arch.interrupt.pending) {
-                                enable_nmi_window(vcpu);
-                        } else if (vcpu->arch.nmi_window_open) {
-                                vcpu->arch.nmi_pending = false;
-                                vcpu->arch.nmi_injected = true;
-                        } else {
-                                enable_nmi_window(vcpu);
-                                return;
-                        }
-                }
-                if (vcpu->arch.nmi_injected) {
-                        vmx_inject_nmi(vcpu);
-                        if (vcpu->arch.nmi_pending)
-                                enable_nmi_window(vcpu);
-                        else if (kvm_cpu_has_interrupt(vcpu))
-                                enable_irq_window(vcpu);
+        if (vcpu->arch.nmi_pending && !vcpu->arch.nmi_injected) {
+                if (vcpu->arch.interrupt.pending) {
+                        enable_nmi_window(vcpu);
+                } else if (vcpu->arch.nmi_window_open) {
+                        vcpu->arch.nmi_pending = false;
+                        vcpu->arch.nmi_injected = true;
+                } else {
+                        enable_nmi_window(vcpu);
                         return;
                 }
         }
+        if (vcpu->arch.nmi_injected) {
+                vmx_inject_nmi(vcpu);
+                if (vcpu->arch.nmi_pending)
+                        enable_nmi_window(vcpu);
+                else if (kvm_cpu_has_interrupt(vcpu))
+                        enable_irq_window(vcpu);
+                return;
+        }
         if (!vcpu->arch.interrupt.pending && kvm_cpu_has_interrupt(vcpu)) {
                 if (vcpu->arch.interrupt_window_open)
                         kvm_queue_interrupt(vcpu, kvm_cpu_get_interrupt(vcpu));
@@ -3255,6 +3307,10 @@ static void vmx_vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
         struct vcpu_vmx *vmx = to_vmx(vcpu);
         u32 intr_info;
 
+        /* Record the guest's net vcpu time for enforced NMI injections. */
+        if (unlikely(!cpu_has_virtual_nmis() && vmx->soft_vnmi_blocked))
+                vmx->entry_time = ktime_get();
+
         /* Handle invalid guest state instead of entering VMX */
         if (vmx->emulation_required && emulate_invalid_guest_state) {
                 handle_invalid_guest_state(vcpu, kvm_run);