Merge tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm

Pull kvm fixes from Paolo Bonzini:
 "Except for the preempt notifiers fix, these are all small bugfixes
  that could have been waited for -rc2.  Sending them now since I was
  taking care of Peter's patch anyway"

* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  kvm: add hyper-v crash msrs values
  KVM: x86: remove data variable from kvm_get_msr_common
  KVM: s390: virtio-ccw: don't overwrite config space values
  KVM: x86: keep track of LVT0 changes under APICv
  KVM: x86: properly restore LVT0
  KVM: x86: make vapics_in_nmi_mode atomic
  sched, preempt_notifier: separate notifier registration from static_key inc/dec

10 files changed, 54 insertions, 16 deletions

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index c7fa57b..2a7f5d7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -607,7 +607,7 @@ struct kvm_arch {
 	struct kvm_pic *vpic;
 	struct kvm_ioapic *vioapic;
 	struct kvm_pit *vpit;
-	int vapics_in_nmi_mode;
+	atomic_t vapics_in_nmi_mode;
 	struct mutex apic_map_lock;
 	struct kvm_apic_map *apic_map;
 
diff --git a/arch/x86/include/uapi/asm/hyperv.h b/arch/x86/include/uapi/asm/hyperv.h
index ce6068d..8fba544 100644
--- a/arch/x86/include/uapi/asm/hyperv.h
+++ b/arch/x86/include/uapi/asm/hyperv.h
@@ -199,6 +199,17 @@
 #define HV_X64_MSR_STIMER3_CONFIG		0x400000B6
 #define HV_X64_MSR_STIMER3_COUNT		0x400000B7
 
+/* Hyper-V guest crash notification MSR's */
+#define HV_X64_MSR_CRASH_P0			0x40000100
+#define HV_X64_MSR_CRASH_P1			0x40000101
+#define HV_X64_MSR_CRASH_P2			0x40000102
+#define HV_X64_MSR_CRASH_P3			0x40000103
+#define HV_X64_MSR_CRASH_P4			0x40000104
+#define HV_X64_MSR_CRASH_CTL			0x40000105
+#define HV_X64_MSR_CRASH_CTL_NOTIFY		(1ULL << 63)
+#define HV_X64_MSR_CRASH_PARAMS		\
+		(1 + (HV_X64_MSR_CRASH_P4 - HV_X64_MSR_CRASH_P0))
+
 #define HV_X64_MSR_HYPERCALL_ENABLE		0x00000001
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_SHIFT	12
 #define HV_X64_MSR_HYPERCALL_PAGE_ADDRESS_MASK	\
diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
index 4dce6f8..f90952f 100644
--- a/arch/x86/kvm/i8254.c
+++ b/arch/x86/kvm/i8254.c
@@ -305,7 +305,7 @@ static void pit_do_work(struct kthread_work *work)
 		 * LVT0 to NMI delivery. Other PIC interrupts are just sent to
 		 * VCPU0, and only if its LVT0 is in EXTINT mode.
 		 */
-		if (kvm->arch.vapics_in_nmi_mode > 0)
+		if (atomic_read(&kvm->arch.vapics_in_nmi_mode) > 0)
 			kvm_for_each_vcpu(i, vcpu, kvm)
 				kvm_apic_nmi_wd_deliver(vcpu);
 	}
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 36e9de1..954e98a 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1257,16 +1257,17 @@ static void start_apic_timer(struct kvm_lapic *apic)
 
 static void apic_manage_nmi_watchdog(struct kvm_lapic *apic, u32 lvt0_val)
 {
-	int nmi_wd_enabled = apic_lvt_nmi_mode(kvm_apic_get_reg(apic, APIC_LVT0));
+	bool lvt0_in_nmi_mode = apic_lvt_nmi_mode(lvt0_val);
 
-	if (apic_lvt_nmi_mode(lvt0_val)) {
-		if (!nmi_wd_enabled) {
+	if (apic->lvt0_in_nmi_mode != lvt0_in_nmi_mode) {
+		apic->lvt0_in_nmi_mode = lvt0_in_nmi_mode;
+		if (lvt0_in_nmi_mode) {
 			apic_debug("Receive NMI setting on APIC_LVT0 "
 				   "for cpu %d\n", apic->vcpu->vcpu_id);
-			apic->vcpu->kvm->arch.vapics_in_nmi_mode++;
-		}
-	} else if (nmi_wd_enabled)
-		apic->vcpu->kvm->arch.vapics_in_nmi_mode--;
+			atomic_inc(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
+		} else
+			atomic_dec(&apic->vcpu->kvm->arch.vapics_in_nmi_mode);
+	}
 }
 
 static int apic_reg_write(struct kvm_lapic *apic, u32 reg, u32 val)
@@ -1597,6 +1598,7 @@ void kvm_lapic_reset(struct kvm_vcpu *vcpu, bool init_event)
 	if (!(vcpu->kvm->arch.disabled_quirks & KVM_QUIRK_LINT0_REENABLED))
 		apic_set_reg(apic, APIC_LVT0,
 			     SET_APIC_DELIVERY_MODE(0, APIC_MODE_EXTINT));
+	apic_manage_nmi_watchdog(apic, kvm_apic_get_reg(apic, APIC_LVT0));
 
 	apic_set_reg(apic, APIC_DFR, 0xffffffffU);
 	apic_set_spiv(apic, 0xff);
@@ -1822,6 +1824,7 @@ void kvm_apic_post_state_restore(struct kvm_vcpu *vcpu,
 	apic_update_ppr(apic);
 	hrtimer_cancel(&apic->lapic_timer.timer);
 	apic_update_lvtt(apic);
+	apic_manage_nmi_watchdog(apic, kvm_apic_get_reg(apic, APIC_LVT0));
 	update_divide_count(apic);
 	start_apic_timer(apic);
 	apic->irr_pending = true;
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index f2f4e10..7195274 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -26,6 +26,7 @@ struct kvm_lapic {
 	struct kvm_vcpu *vcpu;
 	bool sw_enabled;
 	bool irr_pending;
+	bool lvt0_in_nmi_mode;
 	/* Number of bits set in ISR. */
 	s16 isr_count;
 	/* The highest vector set in ISR; if -1 - invalid, must scan ISR. */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ac165c2..bbaf44e 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2379,8 +2379,6 @@ static int get_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 
 int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 {
-	u64 data;
-
 	switch (msr_info->index) {
 	case MSR_IA32_PLATFORM_ID:
 	case MSR_IA32_EBL_CR_POWERON:
@@ -2453,7 +2451,7 @@ int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		/* TSC increment by tick */
 		msr_info->data = 1000ULL;
 		/* CPU multiplier */
-		data |= (((uint64_t)4ULL) << 40);
+		msr_info->data |= (((uint64_t)4ULL) << 40);
 		break;
 	case MSR_EFER:
 		msr_info->data = vcpu->arch.efer;
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index 6f1fa17..f8d8fdb 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -65,6 +65,7 @@ struct virtio_ccw_device {
 	bool is_thinint;
 	bool going_away;
 	bool device_lost;
+	unsigned int config_ready;
 	void *airq_info;
 };
 
@@ -833,8 +834,11 @@ static void virtio_ccw_get_config(struct virtio_device *vdev,
 	if (ret)
 		goto out_free;
 
-	memcpy(vcdev->config, config_area, sizeof(vcdev->config));
-	memcpy(buf, &vcdev->config[offset], len);
+	memcpy(vcdev->config, config_area, offset + len);
+	if (buf)
+		memcpy(buf, &vcdev->config[offset], len);
+	if (vcdev->config_ready < offset + len)
+		vcdev->config_ready = offset + len;
 
 out_free:
 	kfree(config_area);
@@ -857,6 +861,9 @@ static void virtio_ccw_set_config(struct virtio_device *vdev,
 	if (!config_area)
 		goto out_free;
 
+	/* Make sure we don't overwrite fields. */
+	if (vcdev->config_ready < offset)
+		virtio_ccw_get_config(vdev, 0, NULL, offset);
 	memcpy(&vcdev->config[offset], buf, len);
 	/* Write the config area to the host. */
 	memcpy(config_area, vcdev->config, sizeof(vcdev->config));
diff --git a/include/linux/preempt.h b/include/linux/preempt.h
index 0f1534a..84991f1 100644
--- a/include/linux/preempt.h
+++ b/include/linux/preempt.h
@@ -293,6 +293,8 @@ struct preempt_notifier {
 	struct preempt_ops *ops;
 };
 
+void preempt_notifier_inc(void);
+void preempt_notifier_dec(void);
 void preempt_notifier_register(struct preempt_notifier *notifier);
 void preempt_notifier_unregister(struct preempt_notifier *notifier);
 
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5caa029..78b4bad10 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2320,13 +2320,27 @@ void wake_up_new_task(struct task_struct *p)
 
 static struct static_key preempt_notifier_key = STATIC_KEY_INIT_FALSE;
 
+void preempt_notifier_inc(void)
+{
+	static_key_slow_inc(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_inc);
+
+void preempt_notifier_dec(void)
+{
+	static_key_slow_dec(&preempt_notifier_key);
+}
+EXPORT_SYMBOL_GPL(preempt_notifier_dec);
+
 /**
  * preempt_notifier_register - tell me when current is being preempted & rescheduled
  * @notifier: notifier struct to register
  */
 void preempt_notifier_register(struct preempt_notifier *notifier)
 {
-	static_key_slow_inc(&preempt_notifier_key);
+	if (!static_key_false(&preempt_notifier_key))
+		WARN(1, "registering preempt_notifier while notifiers disabled\n");
+
 	hlist_add_head(&notifier->link, &current->preempt_notifiers);
 }
 EXPORT_SYMBOL_GPL(preempt_notifier_register);
@@ -2340,7 +2354,6 @@ EXPORT_SYMBOL_GPL(preempt_notifier_register);
 void preempt_notifier_unregister(struct preempt_notifier *notifier)
 {
 	hlist_del(&notifier->link);
-	static_key_slow_dec(&preempt_notifier_key);
 }
 EXPORT_SYMBOL_GPL(preempt_notifier_unregister);
 
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 848af90..8b8a444 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -553,6 +553,8 @@ static struct kvm *kvm_create_vm(unsigned long type)
 	list_add(&kvm->vm_list, &vm_list);
 	spin_unlock(&kvm_lock);
 
+	preempt_notifier_inc();
+
 	return kvm;
 
 out_err:
@@ -620,6 +622,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
 	cleanup_srcu_struct(&kvm->irq_srcu);
 	cleanup_srcu_struct(&kvm->srcu);
 	kvm_arch_free_vm(kvm);
+	preempt_notifier_dec();
 	hardware_disable_all();
 	mmdrop(mm);
 }