RE: [RFC v2 6/6] KVM: eventfd: add irq bypass consumer management

["Wu, Feng" <feng.wu@intel.com>]

> -----Original Message-----
> From: Eric Auger [mailto:eric.auger@linaro.org]
> Sent: Tuesday, July 07, 2015 5:06 PM
> To: Wu, Feng; eric.auger@st.com; linux-arm-kernel@lists.infradead.org;
> kvmarm@lists.cs.columbia.edu; kvm@vger.kernel.org;
> christoffer.dall@linaro.org; marc.zyngier@arm.com;
> alex.williamson@redhat.com; pbonzini@redhat.com; avi.kivity@gmail.com;
> mtosatti@redhat.com; joro@8bytes.org; b.reynal@virtualopensystems.com
> Cc: linux-kernel@vger.kernel.org; patches@linaro.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@linaro.org]
> >> Sent: Monday, July 06, 2015 8:12 PM
> >> To: eric.auger@st.com; eric.auger@linaro.org;
> >> linux-arm-kernel@lists.infradead.org; kvmarm@lists.cs.columbia.edu;
> >> kvm@vger.kernel.org; christoffer.dall@linaro.org; marc.zyngier@arm.com;
> >> alex.williamson@redhat.com; pbonzini@redhat.com; avi.kivity@gmail.com;
> >> mtosatti@redhat.com; Wu, Feng; joro@8bytes.org;
> >> b.reynal@virtualopensystems.com
> >> Cc: linux-kernel@vger.kernel.org; patches@linaro.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@linaro.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?

Basically, they are fine. I am trying to rebase my patch on top of it. If I
encounter any issues, I will discuss it here ASAP.

Thanks,
Feng

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