linux-kernel - Re: [RFC 16/17] KVM: eventfd: add irq bypass consumer management

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Date:	Thu, 02 Jul 2015 15:53:27 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	Paolo Bonzini <pbonzini@...hat.com>, eric.auger@...com,
	linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
	kvm@...r.kernel.org, christoffer.dall@...aro.org,
	marc.zyngier@....com, alex.williamson@...hat.com,
	avi.kivity@...il.com, mtosatti@...hat.com, feng.wu@...el.com,
	joro@...tes.org, b.reynal@...tualopensystems.com
CC:	linux-kernel@...r.kernel.org, patches@...aro.org
Subject: Re: [RFC 16/17] KVM: eventfd: add irq bypass consumer management

On 07/02/2015 03:42 PM, Paolo Bonzini wrote:
> 
> 
> On 02/07/2015 15:17, Eric Auger wrote:
>> This patch adds the registration/unregistration of an
>> irq_bypass_consumer on irqfd assignment/deassignment.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>> ---
>>  virt/kvm/eventfd.c | 22 +++++++++++++++++++---
>>  1 file changed, 19 insertions(+), 3 deletions(-)
>>
>> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
>> index f3da161..425a47b 100644
>> --- a/virt/kvm/eventfd.c
>> +++ b/virt/kvm/eventfd.c
>> @@ -34,6 +34,7 @@
>>  #include <linux/srcu.h>
>>  #include <linux/slab.h>
>>  #include <linux/seqlock.h>
>> +#include <linux/irqbypass.h>
>>  #include <trace/events/kvm.h>
>>  
>>  #include <kvm/iodev.h>
>> @@ -93,6 +94,7 @@ struct _irqfd {
>>  	struct list_head list;
>>  	poll_table pt;
>>  	struct work_struct shutdown;
>> +	struct irq_bypass_consumer *cons;
>>  };
>>  
>>  static struct workqueue_struct *irqfd_cleanup_wq;
>> @@ -429,7 +431,21 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
>>  	 */
>>  	fdput(f);
>>  
>> -	/* irq_bypass_register_consumer(); */
>> +	irqfd->cons = kzalloc(sizeof(struct irq_bypass_consumer),
>> +			      GFP_KERNEL);
> 
> Apart from the struct embedding technique I suggested in patch 12, this
> looks very reasonable.  Thanks!

Hi Paolo,

thanks for the swift feedback. I will respin shortly with the advised
embedding technique.

Best Regards

Eric
> 
> Paolo
> 
>> +	if (!irqfd->cons) {
>> +		ret = -ENOMEM;
>> +		goto fail;
>> +	}
>> +	irqfd->cons->token = (void *)irqfd->eventfd;
>> +	irqfd->cons->gsi = irqfd->gsi;
>> +	irqfd->cons->kvm = kvm;
>> +	irqfd->cons->add_producer = kvm_arch_add_producer;
>> +	irqfd->cons->del_producer = kvm_arch_del_producer;
>> +	irqfd->cons->stop_consumer = kvm_arch_stop_consumer;
>> +	irqfd->cons->resume_consumer = kvm_arch_resume_consumer;
>> +	ret = irq_bypass_register_consumer(irqfd->cons);
>> +	WARN_ON(ret);
>>  
>>  	return 0;
>>  
>> @@ -530,8 +546,6 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
>>  	struct _irqfd *irqfd, *tmp;
>>  	struct eventfd_ctx *eventfd;
>>  
>> -	/* irq_bypass_unregister_consumer() */
>> -
>>  	eventfd = eventfd_ctx_fdget(args->fd);
>>  	if (IS_ERR(eventfd))
>>  		return PTR_ERR(eventfd);
>> @@ -550,6 +564,8 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd *args)
>>  			irqfd->irq_entry.type = 0;
>>  			write_seqcount_end(&irqfd->irq_entry_sc);
>>  			irqfd_deactivate(irqfd);
>> +			irq_bypass_unregister_consumer(irqfd->cons);
>> +			kfree(irqfd->cons);
>>  		}
>>  	}
>>  
>>

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