Re: [PATCH kernel] vfio/spapr_tce: Set window when adding additional groups to container

[David Gibson <david@gibson.dropbear.id.au>]

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On Tue, Feb 07, 2017 at 12:35:59PM -0700, Alex Williamson wrote:
> On Tue,  7 Feb 2017 17:26:57 +1100
> Alexey Kardashevskiy <aik@ozlabs.ru> wrote:
> 
> > If a container already has a group attached, attaching a new group
> > should just program already created IOMMU tables to the hardware via
> > the iommu_table_group_ops::set_window() callback.
> > 
> > However 6f01cc692 "vfio/spapr: Add a helper to create default DMA window"
> > did not just simplify the code but also removed the set_window() calls
> > in the case of attaching groups to a container which already has tables
> > so it broke VFIO PCI hotplug.
> > 
> > This reverts set_window() bits in tce_iommu_take_ownership_ddw().
> > 
> > Fixes: 6f01cc692
> 
> See Documentation/process/submitting-patches.rst for the expected
> format here, 12 char SHA-1 + --oneline summary.
> 
> > Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > ---
> >  drivers/vfio/vfio_iommu_spapr_tce.c | 21 +++++++++++++++++++++
> >  1 file changed, 21 insertions(+)
> > 
> > diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> > index 7690e5bf3cf1..14c62a8495a2 100644
> > --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> > +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> > @@ -1245,6 +1245,8 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
> >  static long tce_iommu_take_ownership_ddw(struct tce_container *container,
> >  		struct iommu_table_group *table_group)
> >  {
> > +	long i, ret = 0;
> > +
> >  	if (!table_group->ops->create_table || !table_group->ops->set_window ||
> >  			!table_group->ops->release_ownership) {
> >  		WARN_ON_ONCE(1);
> > @@ -1253,7 +1255,26 @@ static long tce_iommu_take_ownership_ddw(struct tce_container *container,
> >  
> >  	table_group->ops->take_ownership(table_group);
> >  
> > +	/* Set all windows to the new group */
> > +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
> > +		struct iommu_table *tbl = container->tables[i];
> 
> checkpatch wants a blank line here.
> 
> > +		if (!tbl)
> > +			continue;
> > +
> > +		ret = table_group->ops->set_window(table_group, i, tbl);
> > +		if (ret)
> > +			goto release_exit;
> > +	}
> > +
> >  	return 0;
> > +
> > +release_exit:
> > +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
> > +		table_group->ops->unset_window(table_group, i);
> > +
> > +	table_group->ops->release_ownership(table_group);
> > +
> > +	return ret;
> >  }
> >  
> >  static int tce_iommu_attach_group(void *iommu_data,
> 
> 
> I've fixed these as shown below.  David, please review/ack as well and
> I'll send a pull for v4.10.  Thanks,
> 
> Alex

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

> 
> 
> commit c019167838156a2efcc60a15fa4207710bac6e82
> Author: Alexey Kardashevskiy <aik@ozlabs.ru>
> Date:   Tue Feb 7 17:26:57 2017 +1100
> 
>     vfio/spapr_tce: Set window when adding additional groups to container
>     
>     If a container already has a group attached, attaching a new group
>     should just program already created IOMMU tables to the hardware via
>     the iommu_table_group_ops::set_window() callback.
>     
>     However commit 6f01cc692a16 ("vfio/spapr: Add a helper to create
>     default DMA window") did not just simplify the code but also removed
>     the set_window() calls in the case of attaching groups to a container
>     which already has tables so it broke VFIO PCI hotplug.
>     
>     This reverts set_window() bits in tce_iommu_take_ownership_ddw().
>     
>     Fixes: 6f01cc692a16 ("vfio/spapr: Add a helper to create default DMA window")
>     Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>     Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> 
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 7690e5bf3cf1..59b3f62a2d64 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -1245,6 +1245,8 @@ static void tce_iommu_release_ownership_ddw(struct tce_container *container,
>  static long tce_iommu_take_ownership_ddw(struct tce_container *container,
>  		struct iommu_table_group *table_group)
>  {
> +	long i, ret = 0;
> +
>  	if (!table_group->ops->create_table || !table_group->ops->set_window ||
>  			!table_group->ops->release_ownership) {
>  		WARN_ON_ONCE(1);
> @@ -1253,7 +1255,27 @@ static long tce_iommu_take_ownership_ddw(struct tce_container *container,
>  
>  	table_group->ops->take_ownership(table_group);
>  
> +	/* Set all windows to the new group */
> +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
> +		struct iommu_table *tbl = container->tables[i];
> +
> +		if (!tbl)
> +			continue;
> +
> +		ret = table_group->ops->set_window(table_group, i, tbl);
> +		if (ret)
> +			goto release_exit;
> +	}
> +
>  	return 0;
> +
> +release_exit:
> +	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i)
> +		table_group->ops->unset_window(table_group, i);
> +
> +	table_group->ops->release_ownership(table_group);
> +
> +	return ret;
>  }
>  
>  static int tce_iommu_attach_group(void *iommu_data,
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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