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 c7fa57b529d2..2a7f5d782c33 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 ce6068dbcfbc..8fba544e9cc4 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 4dce6f8b6129..f90952f64e79 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 36e9de1b4127..954e98a8c2e3 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 f2f4e10ab772..71952748222a 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 ac165c2fb8e5..bbaf44e8f0d3 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 6f1fa1773e76..f8d8fdb26b72 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 0f1534acaf60..84991f185173 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 5caa029dec5d..78b4bad10081 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 848af90b8091..8b8a44453670 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);
 }