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From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
	Joerg Roedel <joro@8bytes.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	David Gibson <david@gibson.dropbear.id.au>,
	Jason Wang <jasowang@redhat.com>,
	"parav@mellanox.com" <parav@mellanox.com>,
	"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Shenming Lu <lushenming@huawei.com>,
	Eric Auger <eric.auger@redhat.com>,
	Jonathan Corbet <corbet@lwn.net>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	Jacob Pan <jacob.jun.pan@linux.intel.com>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	Robin Murphy <robin.murphy@arm.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	David Woodhouse <dwmw2@infradead.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Lu Baolu <baolu.lu@linux.intel.com>
Subject: Re: Plan for /dev/ioasid RFC v2
Date: Mon, 28 Jun 2021 19:48:18 -0300	[thread overview]
Message-ID: <20210628224818.GJ4459@nvidia.com> (raw)
In-Reply-To: <20210628163145.1a21cca9.alex.williamson@redhat.com>

On Mon, Jun 28, 2021 at 04:31:45PM -0600, Alex Williamson wrote:

> I'd expect that /dev/iommu will be used by multiple subsystems.  All
> will want to bind devices to address spaces, so shouldn't binding a
> device to an iommufd be an ioctl on the iommufd, ie.
> IOMMU_BIND_VFIO_DEVICE_FD.  Maybe we don't even need "VFIO" in there and
> the iommufd code can figure it out internally.

It wants to be the other way around because iommu_fd is the lower
level subsystem. We don't/can't teach iommu_fd how to convert a fd
number to a vfio/vdpa/etc/etc, we teach all the things building on
iommu_fd how to change a fd number to an iommu - they already
necessarily have an inter-module linkage.

There is a certain niceness to what you are saying but it is not so
practical without doing something bigger..

> Ideally vfio would also at least be able to register a type1 IOMMU
> backend through the existing uapi, backed by this iommu code, ie. we'd
> create a new "iommufd" (but without the user visible fd), 

It would be amazing to be able to achieve this, at least for me there
are too many details be able to tell what that would look like
exactly. I suggested once that putting the container ioctl interface
in the drivers/iommu code may allow for this without too much trouble..

Jason

WARNING: multiple messages have this Message-ID (diff)
From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	Jason Wang <jasowang@redhat.com>,
	Kirti Wankhede <kwankhede@nvidia.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	"Jiang, Dave" <dave.jiang@intel.com>,
	"Raj, Ashok" <ashok.raj@intel.com>,
	Jonathan Corbet <corbet@lwn.net>,
	"Tian, Kevin" <kevin.tian@intel.com>,
	"parav@mellanox.com" <parav@mellanox.com>,
	"Enrico Weigelt, metux IT consult" <lkml@metux.net>,
	David Gibson <david@gibson.dropbear.id.au>,
	Robin Murphy <robin.murphy@arm.com>,
	LKML <linux-kernel@vger.kernel.org>,
	Shenming Lu <lushenming@huawei.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>
Subject: Re: Plan for /dev/ioasid RFC v2
Date: Mon, 28 Jun 2021 19:48:18 -0300	[thread overview]
Message-ID: <20210628224818.GJ4459@nvidia.com> (raw)
In-Reply-To: <20210628163145.1a21cca9.alex.williamson@redhat.com>

On Mon, Jun 28, 2021 at 04:31:45PM -0600, Alex Williamson wrote:

> I'd expect that /dev/iommu will be used by multiple subsystems.  All
> will want to bind devices to address spaces, so shouldn't binding a
> device to an iommufd be an ioctl on the iommufd, ie.
> IOMMU_BIND_VFIO_DEVICE_FD.  Maybe we don't even need "VFIO" in there and
> the iommufd code can figure it out internally.

It wants to be the other way around because iommu_fd is the lower
level subsystem. We don't/can't teach iommu_fd how to convert a fd
number to a vfio/vdpa/etc/etc, we teach all the things building on
iommu_fd how to change a fd number to an iommu - they already
necessarily have an inter-module linkage.

There is a certain niceness to what you are saying but it is not so
practical without doing something bigger..

> Ideally vfio would also at least be able to register a type1 IOMMU
> backend through the existing uapi, backed by this iommu code, ie. we'd
> create a new "iommufd" (but without the user visible fd), 

It would be amazing to be able to achieve this, at least for me there
are too many details be able to tell what that would look like
exactly. I suggested once that putting the container ioctl interface
in the drivers/iommu code may allow for this without too much trouble..

Jason
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2021-06-28 22:48 UTC|newest]

Thread overview: 162+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-07  2:58 Plan for /dev/ioasid RFC v2 Tian, Kevin
2021-06-07  2:58 ` Tian, Kevin
2021-06-09  8:14 ` Eric Auger
2021-06-09  8:14   ` Eric Auger
2021-06-09  9:37   ` Tian, Kevin
2021-06-09  9:37     ` Tian, Kevin
2021-06-09 10:14     ` Eric Auger
2021-06-09 10:14       ` Eric Auger
2021-06-09  9:01 ` Leon Romanovsky
2021-06-09  9:01   ` Leon Romanovsky
2021-06-09  9:43   ` Tian, Kevin
2021-06-09  9:43     ` Tian, Kevin
2021-06-09 12:24 ` Joerg Roedel
2021-06-09 12:24   ` Joerg Roedel
2021-06-09 12:39   ` Jason Gunthorpe
2021-06-09 12:39     ` Jason Gunthorpe
2021-06-09 13:32     ` Joerg Roedel
2021-06-09 13:32       ` Joerg Roedel
2021-06-09 15:00       ` Jason Gunthorpe
2021-06-09 15:00         ` Jason Gunthorpe
2021-06-09 15:51         ` Joerg Roedel
2021-06-09 15:51           ` Joerg Roedel
2021-06-09 16:15           ` Alex Williamson
2021-06-09 16:15             ` Alex Williamson
2021-06-09 16:27             ` Alex Williamson
2021-06-09 16:27               ` Alex Williamson
2021-06-09 18:49               ` Jason Gunthorpe
2021-06-09 18:49                 ` Jason Gunthorpe
2021-06-10 15:38                 ` Alex Williamson
2021-06-10 15:38                   ` Alex Williamson
2021-06-11  0:58                   ` Tian, Kevin
2021-06-11  0:58                     ` Tian, Kevin
2021-06-11 21:38                     ` Alex Williamson
2021-06-11 21:38                       ` Alex Williamson
2021-06-14  3:09                       ` Tian, Kevin
2021-06-14  3:09                         ` Tian, Kevin
2021-06-14  3:22                         ` Alex Williamson
2021-06-14  3:22                           ` Alex Williamson
2021-06-15  1:05                           ` Tian, Kevin
2021-06-15  1:05                             ` Tian, Kevin
2021-06-14 13:38                         ` Jason Gunthorpe
2021-06-14 13:38                           ` Jason Gunthorpe
2021-06-15  1:21                           ` Tian, Kevin
2021-06-15  1:21                             ` Tian, Kevin
2021-06-15 16:56                             ` Alex Williamson
2021-06-15 16:56                               ` Alex Williamson
2021-06-16  6:53                               ` Tian, Kevin
2021-06-16  6:53                                 ` Tian, Kevin
2021-06-24  4:50                             ` David Gibson
2021-06-24  4:50                               ` David Gibson
2021-06-11 16:45                   ` Jason Gunthorpe
2021-06-11 16:45                     ` Jason Gunthorpe
2021-06-11 19:38                     ` Alex Williamson
2021-06-11 19:38                       ` Alex Williamson
2021-06-12  1:28                       ` Jason Gunthorpe
2021-06-12  1:28                         ` Jason Gunthorpe
2021-06-12 16:57                         ` Alex Williamson
2021-06-12 16:57                           ` Alex Williamson
2021-06-14 14:07                           ` Jason Gunthorpe
2021-06-14 14:07                             ` Jason Gunthorpe
2021-06-14 16:28                             ` Alex Williamson
2021-06-14 16:28                               ` Alex Williamson
2021-06-14 19:40                               ` Jason Gunthorpe
2021-06-14 19:40                                 ` Jason Gunthorpe
2021-06-15  2:31                               ` Tian, Kevin
2021-06-15  2:31                                 ` Tian, Kevin
2021-06-15 16:12                                 ` Alex Williamson
2021-06-15 16:12                                   ` Alex Williamson
2021-06-16  6:43                                   ` Tian, Kevin
2021-06-16  6:43                                     ` Tian, Kevin
2021-06-16 19:39                                     ` Alex Williamson
2021-06-16 19:39                                       ` Alex Williamson
2021-06-17  3:39                                       ` Liu Yi L
2021-06-17  3:39                                         ` Liu Yi L
2021-06-17  7:31                                       ` Tian, Kevin
2021-06-17  7:31                                         ` Tian, Kevin
2021-06-17 21:14                                         ` Alex Williamson
2021-06-17 21:14                                           ` Alex Williamson
2021-06-18  0:19                                           ` Jason Gunthorpe
2021-06-18  0:19                                             ` Jason Gunthorpe
2021-06-18 16:57                                             ` Tian, Kevin
2021-06-18 16:57                                               ` Tian, Kevin
2021-06-18 18:23                                               ` Jason Gunthorpe
2021-06-18 18:23                                                 ` Jason Gunthorpe
2021-06-25 10:27                                                 ` Tian, Kevin
2021-06-25 10:27                                                   ` Tian, Kevin
2021-06-25 14:36                                                   ` Jason Gunthorpe
2021-06-25 14:36                                                     ` Jason Gunthorpe
2021-06-28  1:09                                                     ` Tian, Kevin
2021-06-28  1:09                                                       ` Tian, Kevin
2021-06-28 22:31                                                       ` Alex Williamson
2021-06-28 22:31                                                         ` Alex Williamson
2021-06-28 22:48                                                         ` Jason Gunthorpe [this message]
2021-06-28 22:48                                                           ` Jason Gunthorpe
2021-06-28 23:09                                                           ` Alex Williamson
2021-06-28 23:09                                                             ` Alex Williamson
2021-06-28 23:13                                                             ` Jason Gunthorpe
2021-06-28 23:13                                                               ` Jason Gunthorpe
2021-06-29  0:26                                                               ` Tian, Kevin
2021-06-29  0:26                                                                 ` Tian, Kevin
2021-06-29  0:28                                                             ` Tian, Kevin
2021-06-29  0:28                                                               ` Tian, Kevin
2021-06-29  0:43                                                         ` Tian, Kevin
2021-06-29  0:43                                                           ` Tian, Kevin
2021-06-28  2:03                                                     ` Tian, Kevin
2021-06-28  2:03                                                       ` Tian, Kevin
2021-06-28 14:41                                                       ` Jason Gunthorpe
2021-06-28 14:41                                                         ` Jason Gunthorpe
2021-06-28  6:45                                                     ` Tian, Kevin
2021-06-28  6:45                                                       ` Tian, Kevin
2021-06-28 16:26                                                       ` Jason Gunthorpe
2021-06-28 16:26                                                         ` Jason Gunthorpe
2021-06-24  4:26                                               ` David Gibson
2021-06-24  4:26                                                 ` David Gibson
2021-06-24  5:59                                                 ` Tian, Kevin
2021-06-24  5:59                                                   ` Tian, Kevin
2021-06-24 12:22                                                 ` Lu Baolu
2021-06-24 12:22                                                   ` Lu Baolu
2021-06-24  4:23                                           ` David Gibson
2021-06-24  4:23                                             ` David Gibson
2021-06-18  0:52                                         ` Jason Gunthorpe
2021-06-18  0:52                                           ` Jason Gunthorpe
2021-06-18 13:47                                         ` Joerg Roedel
2021-06-18 13:47                                           ` Joerg Roedel
2021-06-18 15:15                                           ` Jason Gunthorpe
2021-06-18 15:15                                             ` Jason Gunthorpe
2021-06-18 15:37                                             ` Raj, Ashok
2021-06-18 15:37                                               ` Raj, Ashok
2021-06-18 15:51                                               ` Alex Williamson
2021-06-18 15:51                                                 ` Alex Williamson
2021-06-24  4:29                                             ` David Gibson
2021-06-24  4:29                                               ` David Gibson
2021-06-24 11:56                                               ` Jason Gunthorpe
2021-06-24 11:56                                                 ` Jason Gunthorpe
2021-06-18  0:10                                   ` Jason Gunthorpe
2021-06-18  0:10                                     ` Jason Gunthorpe
2021-06-17  5:29                     ` David Gibson
2021-06-17  5:29                       ` David Gibson
2021-06-17  5:02             ` David Gibson
2021-06-17  5:02               ` David Gibson
2021-06-17 23:04               ` Jason Gunthorpe
2021-06-17 23:04                 ` Jason Gunthorpe
2021-06-24  4:37                 ` David Gibson
2021-06-24  4:37                   ` David Gibson
2021-06-24 11:57                   ` Jason Gunthorpe
2021-06-24 11:57                     ` Jason Gunthorpe
2021-06-10  5:50     ` Lu Baolu
2021-06-10  5:50       ` Lu Baolu
2021-06-17  5:22       ` David Gibson
2021-06-17  5:22         ` David Gibson
2021-06-18  5:21         ` Lu Baolu
2021-06-18  5:21           ` Lu Baolu
2021-06-24  4:03           ` David Gibson
2021-06-24  4:03             ` David Gibson
2021-06-24 13:42             ` Lu Baolu
2021-06-24 13:42               ` Lu Baolu
2021-06-17  4:45     ` David Gibson
2021-06-17  4:45       ` David Gibson
2021-06-17 23:10       ` Jason Gunthorpe
2021-06-17 23:10         ` Jason Gunthorpe
2021-06-24  4:07         ` David Gibson
2021-06-24  4:07           ` David Gibson

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