3 files changed, 55 insertions, 4 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index bfbbdea869bf..a40fa8478920 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -398,6 +398,7 @@ struct kvm_vcpu_stat {
         u32 halt_exits;
         u32 halt_wakeup;
         u32 request_irq_exits;
+        u32 request_nmi_exits;
         u32 irq_exits;
         u32 host_state_reload;
         u32 efer_reload;
@@ -406,6 +407,7 @@ struct kvm_vcpu_stat {
         u32 insn_emulation_fail;
         u32 hypercalls;
         u32 irq_injections;
+        u32 nmi_injections;
 };
 
 struct descriptor_table {
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1fa9a6db633d..07971451b947 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -86,6 +86,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
         { "halt_wakeup", VCPU_STAT(halt_wakeup) },
         { "hypercalls", VCPU_STAT(hypercalls) },
         { "request_irq", VCPU_STAT(request_irq_exits) },
+        { "request_nmi", VCPU_STAT(request_nmi_exits) },
         { "irq_exits", VCPU_STAT(irq_exits) },
         { "host_state_reload", VCPU_STAT(host_state_reload) },
         { "efer_reload", VCPU_STAT(efer_reload) },
@@ -93,6 +94,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
         { "insn_emulation", VCPU_STAT(insn_emulation) },
         { "insn_emulation_fail", VCPU_STAT(insn_emulation_fail) },
         { "irq_injections", VCPU_STAT(irq_injections) },
+        { "nmi_injections", VCPU_STAT(nmi_injections) },
         { "mmu_shadow_zapped", VM_STAT(mmu_shadow_zapped) },
         { "mmu_pte_write", VM_STAT(mmu_pte_write) },
         { "mmu_pte_updated", VM_STAT(mmu_pte_updated) },
@@ -1318,6 +1320,15 @@ static int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
         return 0;
 }
 
+static int kvm_vcpu_ioctl_nmi(struct kvm_vcpu *vcpu)
+{
+        vcpu_load(vcpu);
+        kvm_inject_nmi(vcpu);
+        vcpu_put(vcpu);
+
+        return 0;
+}
+
 static int vcpu_ioctl_tpr_access_reporting(struct kvm_vcpu *vcpu,
                                            struct kvm_tpr_access_ctl *tac)
 {
@@ -1377,6 +1388,13 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
                 r = 0;
                 break;
         }
+        case KVM_NMI: {
+                r = kvm_vcpu_ioctl_nmi(vcpu);
+                if (r)
+                        goto out;
+                r = 0;
+                break;
+        }
         case KVM_SET_CPUID: {
                 struct kvm_cpuid __user *cpuid_arg = argp;
                 struct kvm_cpuid cpuid;
@@ -2812,18 +2830,37 @@ static int dm_request_for_irq_injection(struct kvm_vcpu *vcpu,
                 (kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF));
 }
 
+/*
+ * Check if userspace requested a NMI window, and that the NMI window
+ * is open.
+ *
+ * No need to exit to userspace if we already have a NMI queued.
+ */
+static int dm_request_for_nmi_injection(struct kvm_vcpu *vcpu,
+                                        struct kvm_run *kvm_run)
+{
+        return (!vcpu->arch.nmi_pending &&
+                kvm_run->request_nmi_window &&
+                vcpu->arch.nmi_window_open);
+}
+
 static void post_kvm_run_save(struct kvm_vcpu *vcpu,
                               struct kvm_run *kvm_run)
 {
         kvm_run->if_flag = (kvm_x86_ops->get_rflags(vcpu) & X86_EFLAGS_IF) != 0;
         kvm_run->cr8 = kvm_get_cr8(vcpu);
         kvm_run->apic_base = kvm_get_apic_base(vcpu);
-        if (irqchip_in_kernel(vcpu->kvm))
+        if (irqchip_in_kernel(vcpu->kvm)) {
                 kvm_run->ready_for_interrupt_injection = 1;
-        else
+                kvm_run->ready_for_nmi_injection = 1;
+        } else {
                 kvm_run->ready_for_interrupt_injection =
                                         (vcpu->arch.interrupt_window_open &&
                                          vcpu->arch.irq_summary == 0);
+                kvm_run->ready_for_nmi_injection =
+                                        (vcpu->arch.nmi_window_open &&
+                                         vcpu->arch.nmi_pending == 0);
+        }
 }
 
 static void vapic_enter(struct kvm_vcpu *vcpu)
@@ -2999,6 +3036,11 @@ static int __vcpu_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                 }
 
                 if (r > 0) {
+                        if (dm_request_for_nmi_injection(vcpu, kvm_run)) {
+                                r = -EINTR;
+                                kvm_run->exit_reason = KVM_EXIT_NMI;
+                                ++vcpu->stat.request_nmi_exits;
+                        }
                         if (dm_request_for_irq_injection(vcpu, kvm_run)) {
                                 r = -EINTR;
                                 kvm_run->exit_reason = KVM_EXIT_INTR;
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index f18b86fa8655..44fd7fa0af2b 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -83,18 +83,22 @@ struct kvm_irqchip {
 #define KVM_EXIT_S390_SIEIC       13
 #define KVM_EXIT_S390_RESET       14
 #define KVM_EXIT_DCR              15
+#define KVM_EXIT_NMI              16
+#define KVM_EXIT_NMI_WINDOW_OPEN  17
 
 /* for KVM_RUN, returned by mmap(vcpu_fd, offset=0) */
 struct kvm_run {
         /* in */
         __u8 request_interrupt_window;
-        __u8 padding1[7];
+        __u8 request_nmi_window;
+        __u8 padding1[6];
 
         /* out */
         __u32 exit_reason;
         __u8 ready_for_interrupt_injection;
         __u8 if_flag;
-        __u8 padding2[2];
+        __u8 ready_for_nmi_injection;
+        __u8 padding2;
 
         /* in (pre_kvm_run), out (post_kvm_run) */
         __u64 cr8;
@@ -387,6 +391,7 @@ struct kvm_trace_rec {
 #define KVM_CAP_DEVICE_ASSIGNMENT 17
 #endif
 #define KVM_CAP_IOMMU 18
+#define KVM_CAP_NMI 19
 
 /*
  * ioctls for VM fds
@@ -458,6 +463,8 @@ struct kvm_trace_rec {
 #define KVM_S390_INITIAL_RESET    _IO(KVMIO,  0x97)
 #define KVM_GET_MP_STATE          _IOR(KVMIO,  0x98, struct kvm_mp_state)
 #define KVM_SET_MP_STATE          _IOW(KVMIO,  0x99, struct kvm_mp_state)
+/* Available with KVM_CAP_NMI */
+#define KVM_NMI                   _IO(KVMIO,  0x9a)
 
 #define KVM_TRC_INJ_VIRQ         (KVM_TRC_HANDLER + 0x02)
 #define KVM_TRC_REDELIVER_EVT    (KVM_TRC_HANDLER + 0x03)