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Message-ID: <CAFgQCTuuVyX4RH_8hSDuwW268g7ARKD=FtdA9qqtLphBfJ_9Mw@mail.gmail.com>
Date: Tue, 27 Dec 2011 15:53:38 +0800
From: Liu ping fan <kernelfans@...il.com>
To: Gleb Natapov <gleb@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, avi@...hat.com,
aliguori@...ibm.com, mtosatti@...hat.com, jan.kiszka@....de,
Xiao Guangrong <xiaoguangrong.eric@...il.com>
Subject: Re: [PATCH v5] kvm: make vcpu life cycle separated from kvm instance
On Mon, Dec 26, 2011 at 7:09 PM, Gleb Natapov <gleb@...hat.com> wrote:
> On Sat, Dec 17, 2011 at 11:19:35AM +0800, Liu Ping Fan wrote:
>> From: Liu Ping Fan <pingfank@...ux.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@...ux.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.
>
Oh, get it. It opens a gap to make the access to the reclaimed vcpu possible.
> 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.
>
Fine, I find it is very hard to protect both the rcu_list and this
pointer at the same time. And vcpu_id give me a way out.
Thanks and regards,
ping fan
>> + 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.
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