linux-kernel - Re: [PATCH v2 2/9] kvm-vfio: Decouple only when we match a group

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Date:   Mon, 19 Jun 2017 20:42:30 -0600
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Alexey Kardashevskiy <aik@...abs.ru>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org, eric.auger@...hat.com,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH v2 2/9] kvm-vfio: Decouple only when we match a group

On Tue, 20 Jun 2017 12:34:57 +1000
Alexey Kardashevskiy <aik@...abs.ru> wrote:

> On 20/06/17 03:14, Alex Williamson wrote:
> > Unset-KVM and decrement-assignment only when we find the group in our
> > list.  Otherwise we can get out of sync if the user triggers this for
> > groups that aren't currently on our list.
> > 
> > Signed-off-by: Alex Williamson <alex.williamson@...hat.com>
> > Cc: Paolo Bonzini <pbonzini@...hat.com>
> > Cc: Eric Auger <eric.auger@...hat.com>
> > Cc: Alexey Kardashevskiy <aik@...abs.ru>
> > Cc: stable@...r.kernel.org
> > ---
> >  virt/kvm/vfio.c |   12 +++++-------
> >  1 file changed, 5 insertions(+), 7 deletions(-)
> > 
> > diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
> > index 37d9118fd84b..f1b0b7bca9a9 100644
> > --- a/virt/kvm/vfio.c
> > +++ b/virt/kvm/vfio.c
> > @@ -246,21 +246,19 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
> >  				continue;
> >  
> >  			list_del(&kvg->node);
> > +			kvm_arch_end_assignment(dev->kvm);
> > +#ifdef CONFIG_SPAPR_TCE_IOMMU
> > +			kvm_spapr_tce_release_vfio_group(dev->kvm, vfio_group);
> > +#endif
> > +			kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
> >  			kvm_vfio_group_put_external_user(kvg->vfio_group);
> >  			kfree(kvg);
> >  			ret = 0;
> >  			break;
> >  		}
> >  
> > -		kvm_arch_end_assignment(dev->kvm);
> > -
> >  		mutex_unlock(&kv->lock);
> >  
> > -#ifdef CONFIG_SPAPR_TCE_IOMMU
> > -		kvm_spapr_tce_release_vfio_group(dev->kvm, vfio_group);
> > -#endif
> > -		kvm_vfio_group_set_kvm(vfio_group, NULL);  
> 
> 
> Tiny nit: vfio_group becomes kvg->vfio_group in kvm_vfio_group_set_kvm()
> and does not in kvm_spapr_tce_release_vfio_group().
> 
> 
> Anyway,
> 
> Reviewed-by: Alexey Kardashevskiy <aik@...abs.ru>

Thanks, I made the following change for consistency:

diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
index f1b0b7bca9a9..6e002d0f3191 100644
--- a/virt/kvm/vfio.c
+++ b/virt/kvm/vfio.c
@@ -248,7 +248,8 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
 			list_del(&kvg->node);
 			kvm_arch_end_assignment(dev->kvm);
 #ifdef CONFIG_SPAPR_TCE_IOMMU
-			kvm_spapr_tce_release_vfio_group(dev->kvm, vfio_group);
+			kvm_spapr_tce_release_vfio_group(dev->kvm,
+							 kvg->vfio_group);
 #endif
 			kvm_vfio_group_set_kvm(kvg->vfio_group, NULL);
 			kvm_vfio_group_put_external_user(kvg->vfio_group);