[PATCH 3/3] kvm-userspace: Enable user space injected NMI support

[Jan Kiszka <jan.kiszka@siemens.com>]

Make use of the new KVM_NMI IOCTL to push NMIs into the KVM guest if the
user space APIC emulation or some other source raised them.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
 libkvm/libkvm.c     |   31 +++++++++++++++++++++++++++++++
 libkvm/libkvm.h     |   23 +++++++++++++++++++++++
 qemu/qemu-kvm-x86.c |   26 +++++++++++++++++++++++---
 qemu/qemu-kvm.c     |    8 +++++++-
 qemu/qemu-kvm.h     |    1 +
 5 files changed, 85 insertions(+), 4 deletions(-)

Index: b/libkvm/libkvm.c
===================================================================
--- a/libkvm/libkvm.c
+++ b/libkvm/libkvm.c
@@ -811,6 +811,11 @@ int try_push_interrupts(kvm_context_t kv
 	return kvm->callbacks->try_push_interrupts(kvm->opaque);
 }
 
+int try_push_nmi(kvm_context_t kvm)
+{
+	return kvm->callbacks->try_push_nmi(kvm->opaque);
+}
+
 void post_kvm_run(kvm_context_t kvm, int vcpu)
 {
 	kvm->callbacks->post_kvm_run(kvm->opaque, vcpu);
@@ -835,6 +840,17 @@ int kvm_is_ready_for_interrupt_injection
 	return run->ready_for_interrupt_injection;
 }
 
+int kvm_is_ready_for_nmi_injection(kvm_context_t kvm, int vcpu)
+{
+#ifdef KVM_CAP_NMI
+	struct kvm_run *run = kvm->run[vcpu];
+
+	return run->ready_for_nmi_injection;
+#else
+	return 0;
+#endif
+}
+
 int kvm_run(kvm_context_t kvm, int vcpu)
 {
 	int r;
@@ -842,6 +858,9 @@ int kvm_run(kvm_context_t kvm, int vcpu)
 	struct kvm_run *run = kvm->run[vcpu];
 
 again:
+#ifdef KVM_CAP_NMI
+	run->request_nmi_window = try_push_nmi(kvm);
+#endif
 #if !defined(__s390__)
 	if (!kvm->irqchip_in_kernel)
 		run->request_interrupt_window = try_push_interrupts(kvm);
@@ -917,6 +936,9 @@ again:
 			r = handle_halt(kvm, vcpu);
 			break;
 		case KVM_EXIT_IRQ_WINDOW_OPEN:
+#ifdef KVM_CAP_NMI
+		case KVM_EXIT_NMI_WINDOW_OPEN:
+#endif
 			break;
 		case KVM_EXIT_SHUTDOWN:
 			r = handle_shutdown(kvm, vcpu);
@@ -1001,6 +1023,15 @@ int kvm_has_sync_mmu(kvm_context_t kvm)
         return r;
 }
 
+int kvm_inject_nmi(kvm_context_t kvm, int vcpu)
+{
+#ifdef KVM_CAP_NMI
+	return ioctl(kvm->vcpu_fd[vcpu], KVM_NMI);
+#else
+	return -ENOSYS;
+#endif
+}
+
 int kvm_init_coalesced_mmio(kvm_context_t kvm)
 {
 	int r = 0;
Index: b/libkvm/libkvm.h
===================================================================
--- a/libkvm/libkvm.h
+++ b/libkvm/libkvm.h
@@ -66,6 +66,7 @@ struct kvm_callbacks {
     int (*shutdown)(void *opaque, int vcpu);
     int (*io_window)(void *opaque);
     int (*try_push_interrupts)(void *opaque);
+    int (*try_push_nmi)(void *opaque);
     void (*post_kvm_run)(void *opaque, int vcpu);
     int (*pre_kvm_run)(void *opaque, int vcpu);
     int (*tpr_access)(void *opaque, int vcpu, uint64_t rip, int is_write);
@@ -216,6 +217,17 @@ uint64_t kvm_get_apic_base(kvm_context_t
 int kvm_is_ready_for_interrupt_injection(kvm_context_t kvm, int vcpu);
 
 /*!
+ * \brief Check if a vcpu is ready for NMI injection
+ *
+ * This checks if vcpu is not already running in NMI context.
+ *
+ * \param kvm Pointer to the current kvm_context
+ * \param vcpu Which virtual CPU should get dumped
+ * \return boolean indicating NMI injection readiness
+ */
+int kvm_is_ready_for_nmi_injection(kvm_context_t kvm, int vcpu);
+
+/*!
  * \brief Read VCPU registers
  *
  * This gets the GP registers from the VCPU and outputs them
@@ -579,6 +591,17 @@ int kvm_set_lapic(kvm_context_t kvm, int
 
 #endif
 
+/*!
+ * \brief Simulate an NMI
+ *
+ * This allows you to simulate a non-maskable interrupt.
+ *
+ * \param kvm Pointer to the current kvm_context
+ * \param vcpu Which virtual CPU should get dumped
+ * \return 0 on success
+ */
+int kvm_inject_nmi(kvm_context_t kvm, int vcpu);
+
 #endif
 
 /*!
Index: b/qemu/qemu-kvm-x86.c
===================================================================
--- a/qemu/qemu-kvm-x86.c
+++ b/qemu/qemu-kvm-x86.c
@@ -598,7 +598,8 @@ int kvm_arch_halt(void *opaque, int vcpu
     CPUState *env = cpu_single_env;
 
     if (!((env->interrupt_request & CPU_INTERRUPT_HARD) &&
-	  (env->eflags & IF_MASK))) {
+	  (env->eflags & IF_MASK)) &&
+	!(env->interrupt_request & CPU_INTERRUPT_NMI)) {
             env->halted = 1;
 	    env->exception_index = EXCP_HLT;
     }
@@ -627,8 +628,9 @@ void kvm_arch_post_kvm_run(void *opaque,
 
 int kvm_arch_has_work(CPUState *env)
 {
-    if ((env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_EXIT)) &&
-	(env->eflags & IF_MASK))
+    if (((env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_EXIT)) &&
+	 (env->eflags & IF_MASK)) ||
+	(env->interrupt_request & CPU_INTERRUPT_NMI))
 	return 1;
     return 0;
 }
@@ -653,6 +655,24 @@ int kvm_arch_try_push_interrupts(void *o
     return (env->interrupt_request & CPU_INTERRUPT_HARD) != 0;
 }
 
+int kvm_arch_try_push_nmi(void *opaque)
+{
+    CPUState *env = cpu_single_env;
+    int r;
+
+    if (likely(!(env->interrupt_request & CPU_INTERRUPT_NMI)))
+        return 0;
+
+    if (kvm_is_ready_for_nmi_injection(kvm_context, env->cpu_index)) {
+        env->interrupt_request &= ~CPU_INTERRUPT_NMI;
+        r = kvm_inject_nmi(kvm_context, env->cpu_index);
+        if (r < 0)
+            printf("cpu %d fail inject NMI\n", env->cpu_index);
+    }
+
+    return (env->interrupt_request & CPU_INTERRUPT_NMI) != 0;
+}
+
 void kvm_arch_update_regs_for_sipi(CPUState *env)
 {
     SegmentCache cs = env->segs[R_CS];
Index: b/qemu/qemu-kvm.c
===================================================================
--- a/qemu/qemu-kvm.c
+++ b/qemu/qemu-kvm.c
@@ -167,6 +167,11 @@ static int try_push_interrupts(void *opa
     return kvm_arch_try_push_interrupts(opaque);
 }
 
+static int try_push_nmi(void *opaque)
+{
+    return kvm_arch_try_push_nmi(opaque);
+}
+
 static void post_kvm_run(void *opaque, int vcpu)
 {
 
@@ -398,7 +403,7 @@ static int kvm_main_loop_cpu(CPUState *e
     while (1) {
 	while (!has_work(env))
 	    kvm_main_loop_wait(env, 1000);
-	if (env->interrupt_request & CPU_INTERRUPT_HARD)
+	if (env->interrupt_request & (CPU_INTERRUPT_HARD | CPU_INTERRUPT_NMI))
 	    env->halted = 0;
 	if (!kvm_irqchip_in_kernel(kvm_context) && info->sipi_needed)
 	    update_regs_for_sipi(env);
@@ -724,6 +729,7 @@ static struct kvm_callbacks qemu_kvm_ops
     .shutdown = kvm_shutdown,
     .io_window = kvm_io_window,
     .try_push_interrupts = try_push_interrupts,
+    .try_push_nmi = try_push_nmi,
     .post_kvm_run = post_kvm_run,
     .pre_kvm_run = pre_kvm_run,
 #ifdef TARGET_I386
Index: b/qemu/qemu-kvm.h
===================================================================
--- a/qemu/qemu-kvm.h
+++ b/qemu/qemu-kvm.h
@@ -57,6 +57,7 @@ void kvm_arch_pre_kvm_run(void *opaque,
 void kvm_arch_post_kvm_run(void *opaque, int vcpu);
 int kvm_arch_has_work(CPUState *env);
 int kvm_arch_try_push_interrupts(void *opaque);
+int kvm_arch_try_push_nmi(void *opaque);
 void kvm_arch_update_regs_for_sipi(CPUState *env);
 void kvm_arch_cpu_reset(CPUState *env);