[v2] virt: kvm: arm: vgic: Process the failure case when kvm_register_device_ops() fails

Commit Message

Marc Zyngier Nov. 14, 2014, 3:55 p.m. UTC

On 14/11/14 15:18, Chen Gang wrote:
> When kvm_register_device_ops() fails, need disable_percpu_irq(), need
> vgic_arch_unsetup(), need __unregister_cpu_notifier(), and also need
> free_percpu_irq().
> 
> At present, there is no vgic_arch_unsetup(), so add it for resetting
> '__vgic_sr_vectors'.
> 
> 
> Signed-off-by: Chen Gang <[e-mail]>
> ---
>  arch/arm/include/asm/kvm_host.h   |  1 +
>  arch/arm64/include/asm/kvm_host.h |  8 ++++++++
>  virt/kvm/arm/vgic.c               | 19 +++++++++++++++++--
>  3 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> index 53036e2..f68e302 100644
> --- a/arch/arm/include/asm/kvm_host.h
> +++ b/arch/arm/include/asm/kvm_host.h
> @@ -232,6 +232,7 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
>  {
>  	BUG_ON(vgic->type != VGIC_V2);
>  }
> +static inline void vgic_arch_unsetup(void) {}
>  
>  int kvm_perf_init(void);
>  int kvm_perf_teardown(void);
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index 2012c4b..597500c 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -248,6 +248,14 @@ static inline void vgic_arch_setup(const struct vgic_params *vgic)
>  	}
>  }
>  
> +static inline void vgic_arch_unsetup(void)
> +{
> +	extern struct vgic_sr_vectors __vgic_sr_vectors;
> +
> +	__vgic_sr_vectors.save_vgic	= 0;
> +	__vgic_sr_vectors.restore_vgic	= 0;
> +}
> +
>  static inline void kvm_arch_hardware_disable(void) {}
>  static inline void kvm_arch_hardware_unsetup(void) {}
>  static inline void kvm_arch_sync_events(struct kvm *kvm) {}
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 3aaca49..bab81f7 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -2405,6 +2405,11 @@ static void vgic_init_maintenance_interrupt(void *info)
>  	enable_percpu_irq(vgic->maint_irq, 0);
>  }
>  
> +static void vgic_uninit_maintenance_interrupt(void *info)
> +{
> +	disable_percpu_irq(vgic->maint_irq);
> +}
> +
>  static int vgic_cpu_notify(struct notifier_block *self,
>  			   unsigned long action, void *cpu)
>  {
> @@ -2470,9 +2475,19 @@ 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_disable_irq;
> +	}
> +
> +	return 0;
>  
> +out_disable_irq:
> +	on_each_cpu(vgic_uninit_maintenance_interrupt, NULL, 1);
> +	vgic_arch_unsetup();
> +	__unregister_cpu_notifier(&vgic_cpu_nb);
>  out_free_irq:
>  	free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>  	return ret;
> 

No. This is completely overdesigned, and fixes something that really
cannot happen. What is wrong with:


This achieves the exact same effect.

Thanks,

	M.

Comments

Chen Gang Nov. 14, 2014, 4:30 p.m. UTC | #1

According to your taste, we need improve 2 contents below:

On 11/14/2014 11:55 PM, Marc Zyngier wrote:
> 
> No. This is completely overdesigned, and fixes something that really
> cannot happen. What is wrong with:
> 
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 3aaca49..b7dffa80 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -2465,13 +2465,17 @@ int kvm_vgic_hyp_init(void)
>  		goto out_free_irq;
>  	}
>  
> +	ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
> +				       KVM_DEV_TYPE_ARM_VGIC_V2);
> +	if (ret)
> +		goto out_free_irq;
> +

Need call __unregister_cpu_notifier(), since __register_cpu_notifier()
is already successfully called.

Need print some information for failure via kvm_err().

Thanks.
>  	/* Callback into for arch code for setup */
>  	vgic_arch_setup(vgic);
>  
>  	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);
> +	return 0;
>  
>  out_free_irq:
>  	free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
> 
> This achieves the exact same effect.
> 
> Thanks,
> 
> 	M.
>

Chen Gang Nov. 30, 2014, 3:25 a.m. UTC | #2

Hello maintainers:

Is this discussion OK? If necessary, I shall send patch v3 according to
your taste.

Thanks.

On 11/15/14 00:30, Chen Gang wrote:
> 
> According to your taste, we need improve 2 contents below:
> 
> On 11/14/2014 11:55 PM, Marc Zyngier wrote:
>>
>> No. This is completely overdesigned, and fixes something that really
>> cannot happen. What is wrong with:
>>
>> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
>> index 3aaca49..b7dffa80 100644
>> --- a/virt/kvm/arm/vgic.c
>> +++ b/virt/kvm/arm/vgic.c
>> @@ -2465,13 +2465,17 @@ int kvm_vgic_hyp_init(void)
>>  		goto out_free_irq;
>>  	}
>>  
>> +	ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
>> +				       KVM_DEV_TYPE_ARM_VGIC_V2);
>> +	if (ret)
>> +		goto out_free_irq;
>> +
> 
> Need call __unregister_cpu_notifier(), since __register_cpu_notifier()
> is already successfully called.
> 
> Need print some information for failure via kvm_err().
> 
> Thanks.
>>  	/* Callback into for arch code for setup */
>>  	vgic_arch_setup(vgic);
>>  
>>  	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);
>> +	return 0;
>>  
>>  out_free_irq:
>>  	free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());
>>
>> This achieves the exact same effect.
>>
>> Thanks,
>>
>> 	M.
>>
> 
>

Patch

diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
index 3aaca49..b7dffa80 100644
--- a/virt/kvm/arm/vgic.c
+++ b/virt/kvm/arm/vgic.c
@@ -2465,13 +2465,17 @@  int kvm_vgic_hyp_init(void)
 		goto out_free_irq;
 	}
 
+	ret = kvm_register_device_ops(&kvm_arm_vgic_v2_ops,
+				       KVM_DEV_TYPE_ARM_VGIC_V2);
+	if (ret)
+		goto out_free_irq;
+
 	/* Callback into for arch code for setup */
 	vgic_arch_setup(vgic);
 
 	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);
+	return 0;
 
 out_free_irq:
 	free_percpu_irq(vgic->maint_irq, kvm_get_running_vcpus());