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From: Alex Williamson <alex.williamson@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Kirti Wankhede <kwankhede@nvidia.com>,
	Christoph Hellwig <hch@lst.de>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	Diana Craciun <diana.craciun@oss.nxp.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Eric Auger <eric.auger@redhat.com>,
	"Xu, Terrence" <terrence.xu@intel.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1
Date: Thu, 30 Sep 2021 10:46:20 -0600	[thread overview]
Message-ID: <20210930104620.56a1d3e9.alex.williamson@redhat.com> (raw)
In-Reply-To: <20210917125301.GU3544071@ziepe.ca>

On Fri, 17 Sep 2021 09:53:01 -0300
Jason Gunthorpe <jgg@ziepe.ca> wrote:

> On Fri, Sep 17, 2021 at 12:21:07PM +0530, Kirti Wankhede wrote:
> > 
> > 
> > On 9/17/2021 10:35 AM, Christoph Hellwig wrote:  
> > > On Fri, Sep 17, 2021 at 04:49:41AM +0000, Tian, Kevin wrote:  
> > > > > You just use the new style mdev API and directly call
> > > > > vfio_register_group_dev and it will pick up the
> > > > > parent->dev->iommu_group naturally like everything else using physical
> > > > > iommu groups.
> > > > >   
> > > >   
> > 
> > Directly calling vfio_register_group_dev() doesn't work without linking
> > mdev->dev->iommu_group to mdev->type->parent->dev->iommu_group.  
> 
> You pass the PCI device, not the mdev to vfio_register_group_dev().
> 
> > > > For above usage (wrap pdev into mdev), isn't the right way to directly add
> > > > vendor vfio-pci driver since vfio-pci-core has been split out now? It's not
> > > > necessary to fake a mdev just for adding some mediation in the r/w path...  
> > > 
> > > Exactly.  
> > 
> > vfio-pci doesn't provide way to configure the device as mdev framework
> > provide using mdev_types.  
> 
> The linux standard is for a PCI PF driver to configure it's VFs, not a
> mdev or vfio.

Hi Jason,

I'm only aware that the PF driver enables basic SR-IOV configuration of
VFs, ie. the number of enabled VFs.  The mdev interface enables not
only management of the number of child devices, but the flavor of each
child, for example the non-homogeneous slice of resources allocated per
child device.

I think that's the sort of configuration Kirti is asking about here and
I'm not aware of any standard mechanism for a PF driver to apply a
configuration per VF.  A mediated path to a physical device isn't
exclusive to providing features like migration, it can also be used to
create these sorts device flavors.  For example, we might expose NIC VFs
and administrative configuration should restrict VF1 to a 1Gbit
interface while VF2 gets 10Gbit.

Are we left to driver specific sysfs attributes to achieve this or can
we create some form of standardization like mdev provides?  Thanks,

Alex


  reply	other threads:[~2021-09-30 16:46 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-13  7:15 cleanup vfio iommu_group creation v5 Christoph Hellwig
2021-09-13  7:15 ` [PATCH 01/14] vfio: Move vfio_iommu_group_get() to vfio_register_group_dev() Christoph Hellwig
2021-09-14  1:57   ` Tian, Kevin
2021-09-14  5:46     ` Christoph Hellwig
2021-09-14  6:11       ` Tian, Kevin
2021-09-13  7:15 ` [PATCH 02/14] vfio: factor out a vfio_iommu_driver_allowed helper Christoph Hellwig
2021-09-23 22:59   ` Alex Williamson
2021-09-13  7:15 ` [PATCH 03/14] vfio: remove the iommudata check in vfio_noiommu_attach_group Christoph Hellwig
2021-09-13  7:15 ` [PATCH 04/14] vfio: factor out a vfio_group_find_or_alloc helper Christoph Hellwig
2021-09-14  2:00   ` Tian, Kevin
2021-09-13  7:15 ` [PATCH 05/14] vfio: refactor noiommu group creation Christoph Hellwig
2021-09-14  2:07   ` Tian, Kevin
2021-09-13  7:15 ` [PATCH 06/14] vfio: remove the iommudata hack for noiommu groups Christoph Hellwig
2021-09-15 16:44   ` Jason Gunthorpe
2021-09-13  7:15 ` [PATCH 07/14] vfio: simplify iommu group allocation for mediated devices Christoph Hellwig
2021-09-14  2:23   ` Tian, Kevin
2021-09-13  7:16 ` [PATCH 08/14] vfio: remove unused method from vfio_iommu_driver_ops Christoph Hellwig
2021-09-13  7:16 ` [PATCH 09/14] vfio: move the vfio_iommu_driver_ops interface out of <linux/vfio.h> Christoph Hellwig
2021-09-13  7:16 ` [PATCH 10/14] vfio: remove the unused mdev iommu hook Christoph Hellwig
2021-09-13  7:16 ` [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1 Christoph Hellwig
2021-09-16 19:55   ` Kirti Wankhede
2021-09-16 22:18     ` Jason Gunthorpe
2021-09-17  4:49       ` Tian, Kevin
2021-09-17  5:05         ` Christoph Hellwig
2021-09-17  6:51           ` Kirti Wankhede
2021-09-17 12:53             ` Jason Gunthorpe
2021-09-30 16:46               ` Alex Williamson [this message]
2021-09-30 16:57                 ` Jason Gunthorpe
2021-10-01  3:20                   ` Christoph Hellwig
2021-09-13  7:16 ` [PATCH 12/14] vfio/spapr_tce: reject mediated devices Christoph Hellwig
2021-09-13  7:16 ` [PATCH 13/14] vfio/iommu_type1: remove the "external" domain Christoph Hellwig
2021-09-23 22:59   ` Alex Williamson
2021-09-23 23:06     ` Jason Gunthorpe
2021-09-13  7:16 ` [PATCH 14/14] vfio/iommu_type1: remove IS_IOMMU_CAP_DOMAIN_IN_CONTAINER Christoph Hellwig
2021-09-15 18:07 ` cleanup vfio iommu_group creation v5 Jason Gunthorpe
  -- strict thread matches above, loose matches on Subject: below --
2021-08-26 13:34 cleanup vfio iommu_group creation v4 Christoph Hellwig
2021-08-26 13:34 ` [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1 Christoph Hellwig
2021-08-25 16:19 cleanup vfio iommu_group creation v3 Christoph Hellwig
2021-08-25 16:19 ` [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1 Christoph Hellwig
2021-08-26  3:51   ` Tian, Kevin
2021-08-24 14:46 cleanup vfio iommu_group creation v2 Christoph Hellwig
2021-08-24 14:46 ` [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1 Christoph Hellwig
2021-08-25  0:28   ` Jason Gunthorpe
2021-08-25  5:34     ` Christoph Hellwig
2021-08-25 12:35       ` Jason Gunthorpe
2021-08-11 15:14 cleanup vfio iommu_group creation Christoph Hellwig
2021-08-11 15:14 ` [PATCH 11/14] vfio: clean up the check for mediated device in vfio_iommu_type1 Christoph Hellwig

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