linux-kernel - Re: [PATCH] virt: kvm: arm: vgic: Process the failure case when kvm_register_device

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Date:	Fri, 14 Nov 2014 22:05:10 +0800
From:	Chen Gang <gang.chen.5i5j@...il.com>
To:	Marc Zyngier <marc.zyngier@....com>
CC:	"christoffer.dall@...aro.org" <christoffer.dall@...aro.org>,
	"gleb@...nel.org" <gleb@...nel.org>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
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 <gang.chen.5i5j@...il.com>
>> ---
>>  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
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