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From: Jason Gunthorpe <jgg@nvidia.com>
To: Lu Baolu <baolu.lu@linux.intel.com>
Cc: Christoph Hellwig <hch@lst.de>, Joerg Roedel <joro@8bytes.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	ashok.raj@intel.com, sanjay.k.kumar@intel.com,
	jacob.jun.pan@intel.com, kevin.tian@intel.com,
	Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
	yi.l.liu@intel.com, yi.y.sun@intel.com, peterx@redhat.com,
	tiwei.bie@intel.com, xin.zeng@intel.com,
	iommu@lists.linux-foundation.org, kvm@vger.kernel.org,
	Jacob Pan <jacob.jun.pan@linux.intel.com>
Subject: Re: [PATCH v8 7/9] vfio/mdev: Add iommu related member in mdev_device
Date: Tue, 11 May 2021 14:37:03 -0300	[thread overview]
Message-ID: <20210511173703.GO1002214@nvidia.com> (raw)
In-Reply-To: <2d6d3c70-0c6f-2430-3982-2705bfe9f5a6@linux.intel.com>

On Tue, May 11, 2021 at 02:56:05PM +0800, Lu Baolu wrote:

> >     After my next series the mdev drivers will have direct access to
> >     the vfio_device. So an alternative to using the struct device, or
> >     adding 'if mdev' is to add an API to the vfio_device world to
> >     inject what iommu configuration is needed from that direction
> >     instead of trying to discover it from a struct device.
> Just want to make sure that I understand you correctly.
> We should use the existing IOMMU in-kernel APIs to connect mdev with the
> iommu subsystem, so that the upper lays don't need to use something
> like (if dev_is_mdev) to handle mdev differently. Do I get you
> correctly?

After going through all the /dev/ioasid stuff I'm pretty convinced
that none of the PASID use cases for mdev should need any iommu
connection from the mdev_device - this is an artifact of trying to
cram the vfio container and group model into the mdev world and is not
good design.

The PASID interfaces for /dev/ioasid should use the 'struct
pci_device' for everything and never pass in a mdev_device to the
iommu layer.

/dev/ioasid should be designed to support this operation and is why I
strongly want to see the actual vfio_device implementation handle the
connection to the iommu layer and not keep trying to hack through
building what is actually a vfio_device specific connection through
the type1 container code.

> > 3) The vfio_bus_is_mdev() and related symbol_get() nonsense in
> >     drivers/vfio/vfio_iommu_type1.c has to go, for the same reasons
> >     it was not acceptable to do this for the interrupt side either.
> Yes. Agreed. I will look into it.

This will be harder, but the same logic applies - it serves to allow
controlling an ioasid without involving the vfio_device.


  reply	other threads:[~2021-05-11 17:37 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-25  1:30 [PATCH v8 0/9] vfio/mdev: IOMMU aware mediated device Lu Baolu
2019-03-25  1:30 ` [PATCH v8 2/9] iommu/vt-d: Make intel_iommu_enable_pasid() more generic Lu Baolu
2019-03-25  1:30 ` [PATCH v8 3/9] iommu/vt-d: Add per-device IOMMU feature ops entries Lu Baolu
2019-03-25  1:30 ` [PATCH v8 4/9] iommu/vt-d: Move common code out of iommu_attch_device() Lu Baolu
2019-03-25  1:30 ` [PATCH v8 5/9] iommu/vt-d: Aux-domain specific domain attach/detach Lu Baolu
     [not found] ` <20190325013036.18400-1-baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2019-03-25  1:30   ` [PATCH v8 1/9] iommu: Add APIs for multiple domains per device Lu Baolu
2019-03-25  1:30   ` [PATCH v8 6/9] iommu/vt-d: Return ID associated with an auxiliary domain Lu Baolu
2019-03-25  1:30 ` [PATCH v8 7/9] vfio/mdev: Add iommu related member in mdev_device Lu Baolu
2019-03-26  9:32   ` Kirti Wankhede
2019-03-27 14:17     ` Parav Pandit
     [not found]       ` <VI1PR0501MB2271172964AFA3CDD6F1B02CD1580-o1MPJYiShEx8vvm6e75m2MDSnupUy6xnnBOFsp37pqbUKgpGm//BTAC/G2K4zDHf@public.gmane.org>
2019-03-27 18:16         ` Alex Williamson
2019-03-26 17:42   ` Alex Williamson
2021-04-06 20:00   ` Jason Gunthorpe
2021-04-07  1:58     ` Lu Baolu
2021-04-07 11:34       ` Jason Gunthorpe
2021-05-11  6:56     ` Lu Baolu
2021-05-11 17:37       ` Jason Gunthorpe [this message]
2021-05-12  7:46         ` Tian, Kevin
2021-05-17 14:03           ` Jason Gunthorpe
2019-03-25  1:30 ` [PATCH v8 8/9] vfio/type1: Add domain at(de)taching group helpers Lu Baolu
     [not found]   ` <20190325013036.18400-9-baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2019-03-26 17:42     ` Alex Williamson
2019-03-25  1:30 ` [PATCH v8 9/9] vfio/type1: Handle different mdev isolation type Lu Baolu
2019-03-26  9:33   ` Kirti Wankhede
2019-03-26 17:42   ` Alex Williamson
2019-04-11 15:19 ` [PATCH v8 0/9] vfio/mdev: IOMMU aware mediated device Joerg Roedel
2019-04-12  1:36   ` Lu Baolu

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