linux-kernel - Re: [RFC v2 6/6] KVM: eventfd: add irq bypass consumer management

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Date:	Tue, 07 Jul 2015 11:05:51 +0200
From:	Eric Auger <eric.auger@...aro.org>
To:	"Wu, Feng" <feng.wu@...el.com>,
	"eric.auger@...com" <eric.auger@...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>,
	"christoffer.dall@...aro.org" <christoffer.dall@...aro.org>,
	"marc.zyngier@....com" <marc.zyngier@....com>,
	"alex.williamson@...hat.com" <alex.williamson@...hat.com>,
	"pbonzini@...hat.com" <pbonzini@...hat.com>,
	"avi.kivity@...il.com" <avi.kivity@...il.com>,
	"mtosatti@...hat.com" <mtosatti@...hat.com>,
	"joro@...tes.org" <joro@...tes.org>,
	"b.reynal@...tualopensystems.com" <b.reynal@...tualopensystems.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [RFC v2 6/6] KVM: eventfd: add irq bypass consumer management

Hi Feng,
On 07/07/2015 10:47 AM, Wu, Feng wrote:
> 
> 
>> -----Original Message-----
>> From: Eric Auger [mailto:eric.auger@...aro.org]
>> Sent: Monday, July 06, 2015 8:12 PM
>> To: eric.auger@...com; eric.auger@...aro.org;
>> 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; pbonzini@...hat.com; avi.kivity@...il.com;
>> mtosatti@...hat.com; Wu, Feng; joro@...tes.org;
>> b.reynal@...tualopensystems.com
>> Cc: linux-kernel@...r.kernel.org; patches@...aro.org
>> Subject: [RFC v2 6/6] KVM: eventfd: add irq bypass consumer management
>>
>> This patch adds the registration/unregistration of an
>> irq_bypass_consumer on irqfd assignment/deassignment.
>>
>> Signed-off-by: Eric Auger <eric.auger@...aro.org>
>>
>> ---
>>
>> v1 -> v2:
>> - populate of kvm and gsi removed
>> - unregister the consumer on irqfd_shutdown
>> ---
>>  include/linux/kvm_irqfd.h |  1 +
>>  virt/kvm/eventfd.c        | 14 +++++++++++---
>>  2 files changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/kvm_irqfd.h b/include/linux/kvm_irqfd.h
>> index f926b39..3c0bd07 100644
>> --- a/include/linux/kvm_irqfd.h
>> +++ b/include/linux/kvm_irqfd.h
>> @@ -64,6 +64,7 @@ struct kvm_kernel_irqfd {
>>  	struct list_head list;
>>  	poll_table pt;
>>  	struct work_struct shutdown;
>> +	struct irq_bypass_consumer consumer;
>>  };
>>
>>  #endif /* __LINUX_KVM_IRQFD_H */
>> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
>> index b79dc61..9452754 100644
>> --- a/virt/kvm/eventfd.c
>> +++ b/virt/kvm/eventfd.c
>> @@ -35,6 +35,7 @@
>>  #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>
>> @@ -140,6 +141,7 @@ irqfd_shutdown(struct work_struct *work)
>>  	/*
>>  	 * It is now safe to release the object's resources
>>  	 */
>> +	irq_bypass_unregister_consumer(&irqfd->consumer);
>>  	eventfd_ctx_put(irqfd->eventfd);
>>  	kfree(irqfd);
>>  }
>> @@ -380,7 +382,14 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd
>> *args)
>>  	 */
>>  	fdput(f);
>>
>> -	/* irq_bypass_register_consumer(); */
>> +	irqfd->consumer.token = (void *)irqfd->eventfd;
>> +	irqfd->consumer.add_producer = kvm_arch_irq_bypass_add_producer;
>> +	irqfd->consumer.del_producer = kvm_arch_irq_bypass_del_producer;
>> +	irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
>> +	irqfd->consumer.resume = kvm_arch_irq_bypass_resume;
>> +	irqfd->consumer.update = kvm_arch_irq_bypass_update;
>> +	ret = irq_bypass_register_consumer(&irqfd->consumer);
>> +	WARN_ON(ret);
>>
>>  	return 0;
>>
>> @@ -481,8 +490,6 @@ kvm_irqfd_deassign(struct kvm *kvm, struct kvm_irqfd
>> *args)
>>  	struct kvm_kernel_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);
>> @@ -501,6 +508,7 @@ 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->consumer);
> 
> consumer is unregistered in irqfd_shutdown(), why need we do it here?
Yes you're right, this is not needed anymore. Did things too hastily :-(

Otherwise does that isolated series fit your needs for posted interrupts
and match your expectations with regards to split/reusability?

Eric

> 
> Thanks,
> Feng
> 
>>  		}
>>  	}
>>
>> --
>> 1.9.1
> 

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