2014-11-13 15:11:40

by Chen Gang

[permalink] [raw]
Subject: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

When kvm_register_device_ops() fails, also need call free_percpu_irq()
just like others have down within kvm_vgic_hyp_init().

Signed-off-by: Chen Gang <[email protected]>
---
virt/kvm/arm/vgic.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 3aaca49..b799f17 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)

on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);

- return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
- KVM_DEV_TYPE_ARM_VGIC_V2);
+ ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
+ KVM_DEV_TYPE_ARM_VGIC_V2);
+ if (ret) {
+ kvm_err("Cannot register device ops\n");
+ goto out_free_irq;
+ }
+
+ return 0;

out_free_irq:
free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
--
1.9.3


2014-11-13 15:30:41

by Marc Zyngier

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 13/11/14 15:04, Chen Gang wrote:
> When kvm_register_device_ops() fails, also need call free_percpu_irq()
> just like others have down within kvm_vgic_hyp_init().
>
> Signed-off-by: Chen Gang <[email protected]>
> ---
> virt/kvm/arm/vgic.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 3aaca49..b799f17 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>
> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>
> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
> - KVM_DEV_TYPE_ARM_VGIC_V2);
> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
> + KVM_DEV_TYPE_ARM_VGIC_V2);
> + if (ret) {
> + kvm_err("Cannot register device ops\n");
> + goto out_free_irq;
> + }
> +
> + return 0;
>
> out_free_irq:
> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>

Awesome. You're now freeing a per-cpu interrupt after just after having
enabled it on all CPUs. What could possibly go wrong?

M.
--
Jazz is not dead. It just smells funny...

2014-11-14 14:05:28

by Chen Gang

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 11/13/2014 11:30 PM, Marc Zyngier wrote:
> On 13/11/14 15:04, Chen Gang wrote:
>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>> just like others have down within kvm_vgic_hyp_init().
>>
>> Signed-off-by: Chen Gang <[email protected]>
>> ---
>> virt/kvm/arm/vgic.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 3aaca49..b799f17 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>
>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>
>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>> + if (ret) {
>> + kvm_err("Cannot register device ops\n");
>> + goto out_free_irq;
>> + }
>> +
>> + return 0;
>>
>> out_free_irq:
>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>
>
> Awesome. You're now freeing a per-cpu interrupt after just after having
> enabled it on all CPUs. What could possibly go wrong?
>

OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
and need a new function vgic_arch_unsetup() for arm64.

I shall send patch v2 for it.

Thanks.
--
Chen Gang

Open share and attitude like air water and life which God blessed

2014-11-14 14:05:44

by Chen Gang

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 11/13/2014 11:30 PM, Marc Zyngier wrote:
> On 13/11/14 15:04, Chen Gang wrote:
>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>> just like others have down within kvm_vgic_hyp_init().
>>
>> Signed-off-by: Chen Gang <[email protected]>
>> ---
>> virt/kvm/arm/vgic.c | 10 ++++++++--
>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 3aaca49..b799f17 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>
>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>
>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>> + if (ret) {
>> + kvm_err("Cannot register device ops\n");
>> + goto out_free_irq;
>> + }
>> +
>> + return 0;
>>
>> out_free_irq:
>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>
>
> Awesome. You're now freeing a per-cpu interrupt after just after having
> enabled it on all CPUs. What could possibly go wrong?
>

OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
and need a new function vgic_arch_unsetup() for arm64.

I shall send patch v2 for it.

Thanks.
--
Chen Gang

Open share and attitude like air water and life which God blessed

2014-11-14 14:10:04

by Marc Zyngier

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 14/11/14 14:05, Chen Gang wrote:
> On 11/13/2014 11:30 PM, Marc Zyngier wrote:
>> On 13/11/14 15:04, Chen Gang wrote:
>>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>>> just like others have down within kvm_vgic_hyp_init().
>>>
>>> Signed-off-by: Chen Gang <[email protected]>
>>> ---
>>> virt/kvm/arm/vgic.c | 10 ++++++++--
>>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>>> index 3aaca49..b799f17 100644
>>> --- a/virt/kvm/arm/vgic.c
>>> +++ b/virt/kvm/arm/vgic.c
>>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>>
>>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>>
>>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>>> + if (ret) {
>>> + kvm_err("Cannot register device ops\n");
>>> + goto out_free_irq;
>>> + }
>>> +
>>> + return 0;
>>>
>>> out_free_irq:
>>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>>
>>
>> Awesome. You're now freeing a per-cpu interrupt after just after having
>> enabled it on all CPUs. What could possibly go wrong?
>>
>
> OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
> for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
> and need a new function vgic_arch_unsetup() for arm64.

No. Just look at the code. Why don't you just move the
kvm_register_device_ops call *before* enabling the interrupt?

M.
--
Jazz is not dead. It just smells funny...

2014-11-14 14:27:17

by Chen Gang

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 11/14/2014 10:09 PM, Marc Zyngier wrote:
> On 14/11/14 14:05, Chen Gang wrote:
>> On 11/13/2014 11:30 PM, Marc Zyngier wrote:
>>> On 13/11/14 15:04, Chen Gang wrote:
>>>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>>>> just like others have down within kvm_vgic_hyp_init().
>>>>
>>>> Signed-off-by: Chen Gang <[email protected]>
>>>> ---
>>>> virt/kvm/arm/vgic.c | 10 ++++++++--
>>>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>>>> index 3aaca49..b799f17 100644
>>>> --- a/virt/kvm/arm/vgic.c
>>>> +++ b/virt/kvm/arm/vgic.c
>>>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>>>
>>>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>>>
>>>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>>>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>>>> + if (ret) {
>>>> + kvm_err("Cannot register device ops\n");
>>>> + goto out_free_irq;
>>>> + }
>>>> +
>>>> + return 0;
>>>>
>>>> out_free_irq:
>>>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>>>
>>>
>>> Awesome. You're now freeing a per-cpu interrupt after just after having
>>> enabled it on all CPUs. What could possibly go wrong?
>>>
>>
>> OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
>> for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
>> and need a new function vgic_arch_unsetup() for arm64.
>
> No. Just look at the code. Why don't you just move the
> kvm_register_device_ops call *before* enabling the interrupt?
>

Only based on the current code, what you said is reasonable to me.

But in the normal initializing sequence, firstly for architecture
dependence features, then for common cpu features, at last for other
devices (at least, other devices need be the last).

So for me, we need still remain current initializing sequence for
extensible in the future.


Thanks.
--
Chen Gang

Open share and attitude like air water and life which God blessed

2014-11-14 14:53:55

by Marc Zyngier

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 14/11/14 14:27, Chen Gang wrote:
> On 11/14/2014 10:09 PM, Marc Zyngier wrote:
>> On 14/11/14 14:05, Chen Gang wrote:
>>> On 11/13/2014 11:30 PM, Marc Zyngier wrote:
>>>> On 13/11/14 15:04, Chen Gang wrote:
>>>>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>>>>> just like others have down within kvm_vgic_hyp_init().
>>>>>
>>>>> Signed-off-by: Chen Gang <[email protected]>
>>>>> ---
>>>>> virt/kvm/arm/vgic.c | 10 ++++++++--
>>>>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>>>>> index 3aaca49..b799f17 100644
>>>>> --- a/virt/kvm/arm/vgic.c
>>>>> +++ b/virt/kvm/arm/vgic.c
>>>>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>>>>
>>>>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>>>>
>>>>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>>>>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>>>>> + if (ret) {
>>>>> + kvm_err("Cannot register device ops\n");
>>>>> + goto out_free_irq;
>>>>> + }
>>>>> +
>>>>> + return 0;
>>>>>
>>>>> out_free_irq:
>>>>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>>>>
>>>>
>>>> Awesome. You're now freeing a per-cpu interrupt after just after having
>>>> enabled it on all CPUs. What could possibly go wrong?
>>>>
>>>
>>> OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
>>> for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
>>> and need a new function vgic_arch_unsetup() for arm64.
>>
>> No. Just look at the code. Why don't you just move the
>> kvm_register_device_ops call *before* enabling the interrupt?
>>
>
> Only based on the current code, what you said is reasonable to me.
>
> But in the normal initializing sequence, firstly for architecture
> dependence features, then for common cpu features, at last for other
> devices (at least, other devices need be the last).
>
> So for me, we need still remain current initializing sequence for
> extensible in the future.

Well, the current code is what matters to me, not some hypothetical
consideration about how things should (or should not) be.

If you plan to add some code that will require such a refactor, then
post the code together with whatever you want to see changed, and we can
talk about it.

Until then, I'm not willing to take something that looks over-designed
in place of a 4 line fix.

Thanks,

M.
--
Jazz is not dead. It just smells funny...

2014-11-14 15:18:41

by Chen Gang

[permalink] [raw]
Subject: Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

On 11/14/2014 10:53 PM, Marc Zyngier wrote:
> On 14/11/14 14:27, Chen Gang wrote:
>> On 11/14/2014 10:09 PM, Marc Zyngier wrote:
>>> On 14/11/14 14:05, Chen Gang wrote:
>>>> On 11/13/2014 11:30 PM, Marc Zyngier wrote:
>>>>> On 13/11/14 15:04, Chen Gang wrote:
>>>>>> When kvm_register_device_ops() fails, also need call free_percpu_irq()
>>>>>> just like others have down within kvm_vgic_hyp_init().
>>>>>>
>>>>>> Signed-off-by: Chen Gang <[email protected]>
>>>>>> ---
>>>>>> virt/kvm/arm/vgic.c | 10 ++++++++--
>>>>>> 1 file changed, 8 insertions(+), 2 deletions(-)
>>>>>>
>>>>>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>>>>>> index 3aaca49..b799f17 100644
>>>>>> --- a/virt/kvm/arm/vgic.c
>>>>>> +++ b/virt/kvm/arm/vgic.c
>>>>>> @@ -2470,8 +2470,14 @@ int kvm_vgic_hyp_init(void)
>>>>>>
>>>>>> on_each_cpu(vgic_init_maintenance_interrupt, NULL, 1);
>>>>>>
>>>>>> - return kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>>>> - KVM_DEV_TYPE_ARM_VGIC_V2);
>>>>>> + ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>>>>>> + KVM_DEV_TYPE_ARM_VGIC_V2);
>>>>>> + if (ret) {
>>>>>> + kvm_err("Cannot register device ops\n");
>>>>>> + goto out_free_irq;
>>>>>> + }
>>>>>> +
>>>>>> + return 0;
>>>>>>
>>>>>> out_free_irq:
>>>>>> free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>>>>>
>>>>>
>>>>> Awesome. You're now freeing a per-cpu interrupt after just after having
>>>>> enabled it on all CPUs. What could possibly go wrong?
>>>>>
>>>>
>>>> OK, thanks. What you said sound reasonable to me. Need call on_each_cpu
>>>> for disable_percpu_irq(). Also need call __unregister_cpu_notifier(),
>>>> and need a new function vgic_arch_unsetup() for arm64.
>>>
>>> No. Just look at the code. Why don't you just move the
>>> kvm_register_device_ops call *before* enabling the interrupt?
>>>
>>
>> Only based on the current code, what you said is reasonable to me.
>>
>> But in the normal initializing sequence, firstly for architecture
>> dependence features, then for common cpu features, at last for other
>> devices (at least, other devices need be the last).
>>
>> So for me, we need still remain current initializing sequence for
>> extensible in the future.
>
> Well, the current code is what matters to me, not some hypothetical
> consideration about how things should (or should not) be.
>

Different members have different tastes. For me, I want to try to keep
original author's taste no touch (try to keep orginal working flow and
styles).

> If you plan to add some code that will require such a refactor, then
> post the code together with whatever you want to see changed, and we can
> talk about it.
>

OK, thanks. I will send patch v2 for it, next.

> Until then, I'm not willing to take something that looks over-designed
> in place of a 4 line fix.
>

At least, __unregister_cpu_notifier() or kvm_unregister_device_ops() is
requited for us to process the related failure (which exceeds 4 lines).


Thanks.
--
Chen Gang

Open share and attitude like air water and life which God blessed