Re: [PATCH v5] kvm: make vcpu life cycle separated from kvm instance

[Gleb Natapov <gleb@redhat.com>]

On Sat, Dec 17, 2011 at 11:19:35AM +0800, Liu Ping Fan wrote:
> From: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> 
> Currently, vcpu can be destructed only when kvm instance destroyed.
> Change this to vcpu's destruction before kvm instance, so vcpu MUST
> and CAN be destroyed before kvm's destroy.
> 
> Signed-off-by: Liu Ping Fan <pingfank@linux.vnet.ibm.com>
> ---
>  arch/x86/kvm/i8254.c     |   10 +++--
>  arch/x86/kvm/i8259.c     |   12 ++++--
>  arch/x86/kvm/x86.c       |   53 +++++++++++------------
>  include/linux/kvm_host.h |   20 ++++-----
>  virt/kvm/irq_comm.c      |    6 ++-
>  virt/kvm/kvm_main.c      |  106 ++++++++++++++++++++++++++++++++++-----------
>  6 files changed, 132 insertions(+), 75 deletions(-)
> 
> diff --git a/arch/x86/kvm/i8254.c b/arch/x86/kvm/i8254.c
> index 76e3f1c..a3a5506 100644
> --- a/arch/x86/kvm/i8254.c
> +++ b/arch/x86/kvm/i8254.c
> @@ -289,9 +289,8 @@ static void pit_do_work(struct work_struct *work)
>  	struct kvm_pit *pit = container_of(work, struct kvm_pit, expired);
>  	struct kvm *kvm = pit->kvm;
>  	struct kvm_vcpu *vcpu;
> -	int i;
>  	struct kvm_kpit_state *ps = &pit->pit_state;
> -	int inject = 0;
> +	int idx, inject = 0;
>  
>  	/* Try to inject pending interrupts when
>  	 * last one has been acked.
> @@ -315,9 +314,12 @@ static void pit_do_work(struct work_struct *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)
> -			kvm_for_each_vcpu(i, vcpu, kvm)
> +		if (kvm->arch.vapics_in_nmi_mode > 0) {
> +			idx = srcu_read_lock(&kvm->srcu_vcpus);
> +			kvm_for_each_vcpu(vcpu, kvm)
>  				kvm_apic_nmi_wd_deliver(vcpu);
> +			srcu_read_unlock(&kvm->srcu_vcpus, idx);
> +		}
>  	}
>  }
>  
> diff --git a/arch/x86/kvm/i8259.c b/arch/x86/kvm/i8259.c
> index cac4746..5ef5c05 100644
> --- a/arch/x86/kvm/i8259.c
> +++ b/arch/x86/kvm/i8259.c
> @@ -50,25 +50,29 @@ static void pic_unlock(struct kvm_pic *s)
>  {
>  	bool wakeup = s->wakeup_needed;
>  	struct kvm_vcpu *vcpu, *found = NULL;
> -	int i;
> +	struct kvm *kvm = s->kvm;
> +	int idx;
>  
>  	s->wakeup_needed = false;
>  
>  	spin_unlock(&s->lock);
>  
>  	if (wakeup) {
> -		kvm_for_each_vcpu(i, vcpu, s->kvm) {
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(vcpu, kvm)
>  			if (kvm_apic_accept_pic_intr(vcpu)) {
>  				found = vcpu;
>  				break;
>  			}
> -		}
>  
> -		if (!found)
> +		if (!found) {
> +			srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  			return;
> +		}
>  
>  		kvm_make_request(KVM_REQ_EVENT, found);
>  		kvm_vcpu_kick(found);
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  	}
>  }
>  
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 23c93fe..b79739d 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -1774,14 +1774,20 @@ static int get_msr_hyperv_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
>  static int get_msr_hyperv(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
>  {
>  	u64 data = 0;
> +	int idx;
>  
>  	switch (msr) {
>  	case HV_X64_MSR_VP_INDEX: {
> -		int r;
> +		int r = 0;
>  		struct kvm_vcpu *v;
> -		kvm_for_each_vcpu(r, v, vcpu->kvm)
> +		struct kvm *kvm = vcpu->kvm;
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(v, vcpu->kvm) {
>  			if (v == vcpu)
>  				data = r;
> +			r++;
> +		}
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  		break;
>  	}
>  	case HV_X64_MSR_EOI:
> @@ -4529,7 +4535,7 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
>  	struct cpufreq_freqs *freq = data;
>  	struct kvm *kvm;
>  	struct kvm_vcpu *vcpu;
> -	int i, send_ipi = 0;
> +	int idx, send_ipi = 0;
>  
>  	/*
>  	 * We allow guests to temporarily run on slowing clocks,
> @@ -4579,13 +4585,16 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
>  
>  	raw_spin_lock(&kvm_lock);
>  	list_for_each_entry(kvm, &vm_list, vm_list) {
> -		kvm_for_each_vcpu(i, vcpu, kvm) {
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(vcpu, kvm) {
>  			if (vcpu->cpu != freq->cpu)
>  				continue;
>  			kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
>  			if (vcpu->cpu != smp_processor_id())
>  				send_ipi = 1;
>  		}
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
> +
>  	}
>  	raw_spin_unlock(&kvm_lock);
>  
> @@ -5866,13 +5875,17 @@ int kvm_arch_hardware_enable(void *garbage)
>  {
>  	struct kvm *kvm;
>  	struct kvm_vcpu *vcpu;
> -	int i;
> +	int idx;
>  
>  	kvm_shared_msr_cpu_online();
> -	list_for_each_entry(kvm, &vm_list, vm_list)
> -		kvm_for_each_vcpu(i, vcpu, kvm)
> +	list_for_each_entry(kvm, &vm_list, vm_list) {
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(vcpu, kvm) {
>  			if (vcpu->cpu == smp_processor_id())
>  				kvm_make_request(KVM_REQ_CLOCK_UPDATE, vcpu);
> +		}
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
> +	}
>  	return kvm_x86_ops->hardware_enable(garbage);
>  }
>  
> @@ -5989,27 +6002,14 @@ static void kvm_unload_vcpu_mmu(struct kvm_vcpu *vcpu)
>  	vcpu_put(vcpu);
>  }
>  
> -static void kvm_free_vcpus(struct kvm *kvm)
> +void kvm_arch_vcpu_zap(struct kvm_vcpu *vcpu)
>  {
> -	unsigned int i;
> -	struct kvm_vcpu *vcpu;
> -
> -	/*
> -	 * Unpin any mmu pages first.
> -	 */
> -	kvm_for_each_vcpu(i, vcpu, kvm) {
> -		kvm_clear_async_pf_completion_queue(vcpu);
> -		kvm_unload_vcpu_mmu(vcpu);
> -	}
> -	kvm_for_each_vcpu(i, vcpu, kvm)
> -		kvm_arch_vcpu_free(vcpu);
> -
> -	mutex_lock(&kvm->lock);
> -	for (i = 0; i < atomic_read(&kvm->online_vcpus); i++)
> -		kvm->vcpus[i] = NULL;
> +	struct kvm *kvm = vcpu->kvm;
>  
> -	atomic_set(&kvm->online_vcpus, 0);
> -	mutex_unlock(&kvm->lock);
> +	kvm_clear_async_pf_completion_queue(vcpu);
> +	kvm_unload_vcpu_mmu(vcpu);
> +	kvm_arch_vcpu_free(vcpu);
> +	kvm_put_kvm(kvm);
>  }
>  
>  void kvm_arch_sync_events(struct kvm *kvm)
> @@ -6023,7 +6023,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
>  	kvm_iommu_unmap_guest(kvm);
>  	kfree(kvm->arch.vpic);
>  	kfree(kvm->arch.vioapic);
> -	kvm_free_vcpus(kvm);
>  	if (kvm->arch.apic_access_page)
>  		put_page(kvm->arch.apic_access_page);
>  	if (kvm->arch.ept_identity_pagetable)
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 8c5c303..ab22828 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -115,6 +115,7 @@ enum {
>  
>  struct kvm_vcpu {
>  	struct kvm *kvm;
> +	struct list_head list;
>  #ifdef CONFIG_PREEMPT_NOTIFIERS
>  	struct preempt_notifier preempt_notifier;
>  #endif
> @@ -249,13 +250,15 @@ struct kvm {
>  	struct mm_struct *mm; /* userspace tied to this vm */
>  	struct kvm_memslots *memslots;
>  	struct srcu_struct srcu;
> +	struct srcu_struct srcu_vcpus;
> +
>  #ifdef CONFIG_KVM_APIC_ARCHITECTURE
>  	u32 bsp_vcpu_id;
>  	struct kvm_vcpu *bsp_vcpu;
Rebase to latest kvm.git.

>  #endif
> -	struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
> +	struct list_head vcpus;
>  	atomic_t online_vcpus;
> -	int last_boosted_vcpu;
> +	struct kvm_vcpu *last_boosted_vcpu;
>  	struct list_head vm_list;
>  	struct mutex lock;
>  	struct kvm_io_bus *buses[KVM_NR_BUSES];
> @@ -302,17 +305,10 @@ struct kvm {
>  #define kvm_printf(kvm, fmt ...) printk(KERN_DEBUG fmt)
>  #define vcpu_printf(vcpu, fmt...) kvm_printf(vcpu->kvm, fmt)
>  
> -static inline struct kvm_vcpu *kvm_get_vcpu(struct kvm *kvm, int i)
> -{
> -	smp_rmb();
> -	return kvm->vcpus[i];
> -}
> +void kvm_arch_vcpu_zap(struct kvm_vcpu *vcpu);
>  
> -#define kvm_for_each_vcpu(idx, vcpup, kvm) \
> -	for (idx = 0; \
> -	     idx < atomic_read(&kvm->online_vcpus) && \
> -	     (vcpup = kvm_get_vcpu(kvm, idx)) != NULL; \
> -	     idx++)
> +#define kvm_for_each_vcpu(vcpu, kvm) \
> +	list_for_each_entry_rcu(vcpu, &kvm->vcpus, list)
>  
>  #define kvm_for_each_memslot(memslot, slots)	\
>  	for (memslot = &slots->memslots[0];	\
> diff --git a/virt/kvm/irq_comm.c b/virt/kvm/irq_comm.c
> index 9f614b4..78dc97c 100644
> --- a/virt/kvm/irq_comm.c
> +++ b/virt/kvm/irq_comm.c
> @@ -81,14 +81,15 @@ inline static bool kvm_is_dm_lowest_prio(struct kvm_lapic_irq *irq)
>  int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
>  		struct kvm_lapic_irq *irq)
>  {
> -	int i, r = -1;
> +	int idx, r = -1;
>  	struct kvm_vcpu *vcpu, *lowest = NULL;
>  
>  	if (irq->dest_mode == 0 && irq->dest_id == 0xff &&
>  			kvm_is_dm_lowest_prio(irq))
>  		printk(KERN_INFO "kvm: apic: phys broadcast and lowest prio\n");
>  
> -	kvm_for_each_vcpu(i, vcpu, kvm) {
> +	idx = srcu_read_lock(&kvm->srcu_vcpus);
> +	kvm_for_each_vcpu(vcpu, kvm) {
>  		if (!kvm_apic_present(vcpu))
>  			continue;
>  
> @@ -111,6 +112,7 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
>  	if (lowest)
>  		r = kvm_apic_set_irq(lowest, irq);
>  
> +	srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  	return r;
>  }
>  
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e289486..ec0c920 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -171,7 +171,7 @@ static void ack_flush(void *_completed)
>  
>  static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
>  {
> -	int i, cpu, me;
> +	int cpu, me, idx;
>  	cpumask_var_t cpus;
>  	bool called = true;
>  	struct kvm_vcpu *vcpu;
> @@ -179,7 +179,8 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
>  	zalloc_cpumask_var(&cpus, GFP_ATOMIC);
>  
>  	me = get_cpu();
> -	kvm_for_each_vcpu(i, vcpu, kvm) {
> +	idx = srcu_read_lock(&kvm->srcu_vcpus);
> +	kvm_for_each_vcpu(vcpu, kvm) {
>  		kvm_make_request(req, vcpu);
>  		cpu = vcpu->cpu;
>  
> @@ -190,12 +191,15 @@ static bool make_all_cpus_request(struct kvm *kvm, unsigned int req)
>  		      kvm_vcpu_exiting_guest_mode(vcpu) != OUTSIDE_GUEST_MODE)
>  			cpumask_set_cpu(cpu, cpus);
>  	}
> +	srcu_read_unlock(&kvm->srcu_vcpus, idx);
> +
>  	if (unlikely(cpus == NULL))
>  		smp_call_function_many(cpu_online_mask, ack_flush, NULL, 1);
>  	else if (!cpumask_empty(cpus))
>  		smp_call_function_many(cpus, ack_flush, NULL, 1);
>  	else
>  		called = false;
> +
>  	put_cpu();
>  	free_cpumask_var(cpus);
>  	return called;
> @@ -477,6 +481,8 @@ static struct kvm *kvm_create_vm(void)
>  	kvm_init_memslots_id(kvm);
>  	if (init_srcu_struct(&kvm->srcu))
>  		goto out_err_nosrcu;
> +	if (init_srcu_struct(&kvm->srcu_vcpus))
> +		goto out_err_nosrcu_vcpus;
>  	for (i = 0; i < KVM_NR_BUSES; i++) {
>  		kvm->buses[i] = kzalloc(sizeof(struct kvm_io_bus),
>  					GFP_KERNEL);
> @@ -500,10 +506,13 @@ static struct kvm *kvm_create_vm(void)
>  	raw_spin_lock(&kvm_lock);
>  	list_add(&kvm->vm_list, &vm_list);
>  	raw_spin_unlock(&kvm_lock);
> +	INIT_LIST_HEAD(&kvm->vcpus);
>  
>  	return kvm;
>  
>  out_err:
> +	cleanup_srcu_struct(&kvm->srcu_vcpus);
> +out_err_nosrcu_vcpus:
>  	cleanup_srcu_struct(&kvm->srcu);
>  out_err_nosrcu:
>  	hardware_disable_all();
> @@ -587,6 +596,7 @@ static void kvm_destroy_vm(struct kvm *kvm)
>  	kvm_arch_destroy_vm(kvm);
>  	kvm_free_physmem(kvm);
>  	cleanup_srcu_struct(&kvm->srcu);
> +	cleanup_srcu_struct(&kvm->srcu_vcpus);
>  	kvm_arch_free_vm(kvm);
>  	hardware_disable_all();
>  	mmdrop(mm);
> @@ -1593,11 +1603,9 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>  {
>  	struct kvm *kvm = me->kvm;
>  	struct kvm_vcpu *vcpu;
> -	int last_boosted_vcpu = me->kvm->last_boosted_vcpu;
> -	int yielded = 0;
> -	int pass;
> -	int i;
> -
> +	struct task_struct *task = NULL;
> +	struct pid *pid;
> +	int pass, firststart, lastone, yielded, idx;
>  	/*
>  	 * We boost the priority of a VCPU that is runnable but not
>  	 * currently running, because it got preempted by something
> @@ -1605,15 +1613,22 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>  	 * VCPU is holding the lock that we need and will release it.
>  	 * We approximate round-robin by starting at the last boosted VCPU.
>  	 */
> -	for (pass = 0; pass < 2 && !yielded; pass++) {
> -		kvm_for_each_vcpu(i, vcpu, kvm) {
> -			struct task_struct *task = NULL;
> -			struct pid *pid;
> -			if (!pass && i < last_boosted_vcpu) {
> -				i = last_boosted_vcpu;
> +	for (pass = 0, firststart = 0; pass < 2 && !yielded; pass++) {
> +
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(vcpu, kvm) {
> +			if (!pass && !firststart &&
> +			    vcpu != kvm->last_boosted_vcpu &&
> +			    kvm->last_boosted_vcpu != NULL) {
> +				vcpu = kvm->last_boosted_vcpu;
You access last_boosted_vcpu as if it is protected by srcu, but it
isn't. kvm_vcpu_release() changes it after synchronize_srcu_expedited()
call.

I do not like this last_boosted_vcpu pointer much. May be we can rid of
it by remembering last apic_id and searching for it each time we enter
the function. I do not think this function is to performance sensitive.
We enter here when vcpu is spinning anyway.

> +				firststart = 1;
>  				continue;
> -			} else if (pass && i > last_boosted_vcpu)
> +			} else if (pass && !lastone) {
> +				if (vcpu == kvm->last_boosted_vcpu)
> +					lastone = 1;
> +			} else if (pass && lastone)
>  				break;
> +
>  			if (vcpu == me)
>  				continue;
>  			if (waitqueue_active(&vcpu->wq))
> @@ -1629,15 +1644,20 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me)
>  				put_task_struct(task);
>  				continue;
>  			}
> +
>  			if (yield_to(task, 1)) {
>  				put_task_struct(task);
> -				kvm->last_boosted_vcpu = i;
> +				mutex_lock(&kvm->lock);
> +				kvm->last_boosted_vcpu = vcpu;
> +				mutex_unlock(&kvm->lock);
>  				yielded = 1;
>  				break;
>  			}
>  			put_task_struct(task);
>  		}
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  	}
> +
>  }
>  EXPORT_SYMBOL_GPL(kvm_vcpu_on_spin);
>  
> @@ -1673,11 +1693,30 @@ static int kvm_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
>  	return 0;
>  }
>  
> +static void kvm_vcpu_zap(struct kvm_vcpu *vcpu)
> +{
> +	kvm_arch_vcpu_zap(vcpu);
> +}
> +
>  static int kvm_vcpu_release(struct inode *inode, struct file *filp)
>  {
>  	struct kvm_vcpu *vcpu = filp->private_data;
> +	struct kvm *kvm = vcpu->kvm;
> +	filp->private_data = NULL;
> +
> +	mutex_lock(&kvm->lock);
> +	list_del_rcu(&vcpu->list);
> +	atomic_dec(&kvm->online_vcpus);
> +	mutex_unlock(&kvm->lock);
> +	synchronize_srcu_expedited(&kvm->srcu_vcpus);
> +
> +	mutex_lock(&kvm->lock);
> +	if (kvm->last_boosted_vcpu == vcpu)
> +		kvm->last_boosted_vcpu = NULL;
> +	mutex_unlock(&kvm->lock);
>  
> -	kvm_put_kvm(vcpu->kvm);
> +	/*vcpu is out of list,drop it safely*/
> +	kvm_vcpu_zap(vcpu);
>  	return 0;
>  }
>  
> @@ -1699,15 +1738,25 @@ static int create_vcpu_fd(struct kvm_vcpu *vcpu)
>  	return anon_inode_getfd("kvm-vcpu", &kvm_vcpu_fops, vcpu, O_RDWR);
>  }
>  
> +static struct kvm_vcpu *kvm_vcpu_create(struct kvm *kvm, u32 id)
> +{
> +	struct kvm_vcpu *vcpu;
> +	vcpu = kvm_arch_vcpu_create(kvm, id);
> +	if (IS_ERR(vcpu))
> +		return vcpu;
> +	INIT_LIST_HEAD(&vcpu->list);
> +	return vcpu;
> +}
> +
>  /*
>   * Creates some virtual cpus.  Good luck creating more than one.
>   */
>  static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  {
> -	int r;
> +	int r, idx;
>  	struct kvm_vcpu *vcpu, *v;
>  
> -	vcpu = kvm_arch_vcpu_create(kvm, id);
> +	vcpu = kvm_vcpu_create(kvm, id);
>  	if (IS_ERR(vcpu))
>  		return PTR_ERR(vcpu);
>  
> @@ -1723,13 +1772,15 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  		goto unlock_vcpu_destroy;
>  	}
>  
> -	kvm_for_each_vcpu(r, v, kvm)
> +	idx = srcu_read_lock(&kvm->srcu_vcpus);
> +	kvm_for_each_vcpu(v, kvm) {
>  		if (v->vcpu_id == id) {
>  			r = -EEXIST;
> +			srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  			goto unlock_vcpu_destroy;
>  		}
> -
> -	BUG_ON(kvm->vcpus[atomic_read(&kvm->online_vcpus)]);
> +	}
> +	srcu_read_unlock(&kvm->srcu_vcpus, idx);
>  
>  	/* Now it's all set up, let userspace reach it */
>  	kvm_get_kvm(kvm);
> @@ -1739,8 +1790,8 @@ static int kvm_vm_ioctl_create_vcpu(struct kvm *kvm, u32 id)
>  		goto unlock_vcpu_destroy;
>  	}
>  
> -	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = vcpu;
> -	smp_wmb();
> +	/*Protected by kvm->lock*/
> +	list_add_rcu(&vcpu->list, &kvm->vcpus);
>  	atomic_inc(&kvm->online_vcpus);
>  
>  #ifdef CONFIG_KVM_APIC_ARCHITECTURE
> @@ -2645,13 +2696,16 @@ static int vcpu_stat_get(void *_offset, u64 *val)
>  	unsigned offset = (long)_offset;
>  	struct kvm *kvm;
>  	struct kvm_vcpu *vcpu;
> -	int i;
> +	int idx;
>  
>  	*val = 0;
>  	raw_spin_lock(&kvm_lock);
> -	list_for_each_entry(kvm, &vm_list, vm_list)
> -		kvm_for_each_vcpu(i, vcpu, kvm)
> +	list_for_each_entry(kvm, &vm_list, vm_list) {
> +		idx = srcu_read_lock(&kvm->srcu_vcpus);
> +		kvm_for_each_vcpu(vcpu, kvm)
>  			*val += *(u32 *)((void *)vcpu + offset);
> +		srcu_read_unlock(&kvm->srcu_vcpus, idx);
> +	}
>  
>  	raw_spin_unlock(&kvm_lock);
>  	return 0;
> -- 
> 1.7.4.4

--
			Gleb.