linux-kernel - Re: [RFC 8/9] KVM: KVM-VFIO: add kvm_vfio_arch

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Message-ID: <1409153842.2906.255.camel@ul30vt.home>
Date:	Wed, 27 Aug 2014 09:37:22 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Eric Auger <eric.auger@...aro.org>
Cc:	eric.auger@...com, christoffer.dall@...aro.org,
	marc.zyngier@....com, linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
	joel.schopp@....com, kim.phillips@...escale.com,
	linux-kernel@...r.kernel.org, patches@...aro.org,
	will.deacon@....com, a.motakis@...tualopensystems.com,
	a.rigo@...tualopensystems.com, john.liuli@...wei.com
Subject: Re: [RFC 8/9] KVM: KVM-VFIO: add kvm_vfio_arch_data and accessors

On Wed, 2014-08-27 at 17:22 +0200, Eric Auger wrote:
> On 08/26/2014 09:02 PM, Alex Williamson wrote:
> > On Mon, 2014-08-25 at 15:27 +0200, Eric Auger wrote:
> >> add a pointer to architecture specific data in kvm_vfio struct
> >> add accessors to keep kvm_vfio private
> >>
> >> Signed-off-by: Eric Auger <eric.auger@...aro.org>
> >> ---
> >>  arch/arm/include/asm/kvm_host.h |  8 ++++++++
> >>  virt/kvm/vfio.c                 | 21 +++++++++++++++++++++
> >>  2 files changed, 29 insertions(+)
> >>
> >> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> >> index 62cbf5b..4f1edbf 100644
> >> --- a/arch/arm/include/asm/kvm_host.h
> >> +++ b/arch/arm/include/asm/kvm_host.h
> >> @@ -177,6 +177,14 @@ void kvm_vfio_device_put_external_user(struct vfio_device *vdev);
> >>  int kvm_vfio_external_get_type(struct vfio_device *vdev);
> >>  struct device *kvm_vfio_external_get_base_device(struct vfio_device *vdev);
> >>  
> >> +struct kvm_vfio;
> >> +struct kvm_vfio_arch_data;
> >> +void kvm_vfio_device_set_arch_data(struct kvm_vfio *kv,
> >> +				   struct kvm_vfio_arch_data *ptr);
> >> +struct kvm_vfio_arch_data *kvm_vfio_device_get_arch_data(struct kvm_vfio *kv);
> >> +void kvm_vfio_lock(struct kvm_vfio *kv);
> >> +void kvm_vfio_unlock(struct kvm_vfio *kv);
> >> +
> >>  /* We do not have shadow page tables, hence the empty hooks */
> >>  static inline int kvm_age_hva(struct kvm *kvm, unsigned long hva)
> >>  {
> >> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> >> index f1c4e35..177b71e 100644
> >> --- a/virt/kvm/vfio.c
> >> +++ b/virt/kvm/vfio.c
> >> @@ -28,6 +28,7 @@ struct kvm_vfio {
> >>  	struct list_head group_list;
> >>  	struct mutex lock;
> >>  	bool noncoherent;
> >> +	struct kvm_vfio_arch_data *arch_data;
> >>  };
> >>  
> >>  static struct vfio_group *kvm_vfio_group_get_external_user(struct file *filep)
> >> @@ -338,6 +339,26 @@ static int kvm_vfio_create(struct kvm_device *dev, u32 type)
> >>  	return 0;
> >>  }
> >>  
> >> +void kvm_vfio_device_set_arch_data(struct kvm_vfio *kv,
> >> +				   struct kvm_vfio_arch_data *ptr)
> >> +{
> >> +	kv->arch_data = ptr;
> >> +}
> >> +
> >> +struct kvm_vfio_arch_data *kvm_vfio_device_get_arch_data(struct kvm_vfio *kv)
> >> +{
> > 
> > My preference would be s/get_//
> ok
> > 
> >> +	return kv->arch_data;
> >> +}
> >> +
> >> +void kvm_vfio_lock(struct kvm_vfio *kv)
> >> +{
> >> +	mutex_lock(&kv->lock);
> >> +}
> >> +
> >> +void kvm_vfio_unlock(struct kvm_vfio *kv)
> >> +{
> >> +	mutex_unlock(&kv->lock);
> >> +}
> > 
> > Gosh, what could go wrong...
> Hum sorry I did not understand what you meant here

Sorry, I was just sarcastically noting that exposing an internal lock
like this seems to be asking for trouble.  As you rework it to pull more
into the common code and generalize the architecture callouts, I hope we
can avoid exporting these locks.  Thanks,

Alex

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