From: Jason Gunthorpe <jgg@nvidia.com>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: LKML <linux-kernel@vger.kernel.org>,
Joerg Roedel <joro@8bytes.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
David Woodhouse <dwmw2@infradead.org>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"Alex Williamson (alex.williamson@redhat.com)"
<alex.williamson@redhat.com>, Jason Wang <jasowang@redhat.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>,
Jean-Philippe Brucker <jean-philippe@linaro.org>,
David Gibson <david@gibson.dropbear.id.au>,
Kirti Wankhede <kwankhede@nvidia.com>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [RFC] /dev/ioasid uAPI proposal
Date: Tue, 1 Jun 2021 17:28:34 -0300 [thread overview]
Message-ID: <20210601202834.GR1002214@nvidia.com> (raw)
In-Reply-To: <MWHPR11MB188685D57653827B566BF9B38C3E9@MWHPR11MB1886.namprd11.prod.outlook.com>
On Tue, Jun 01, 2021 at 07:01:57AM +0000, Tian, Kevin wrote:
> > From: Jason Gunthorpe <jgg@nvidia.com>
> > Sent: Saturday, May 29, 2021 4:03 AM
> >
> > On Thu, May 27, 2021 at 07:58:12AM +0000, Tian, Kevin wrote:
> > > /dev/ioasid provides an unified interface for managing I/O page tables for
> > > devices assigned to userspace. Device passthrough frameworks (VFIO,
> > vDPA,
> > > etc.) are expected to use this interface instead of creating their own logic to
> > > isolate untrusted device DMAs initiated by userspace.
> >
> > It is very long, but I think this has turned out quite well. It
> > certainly matches the basic sketch I had in my head when we were
> > talking about how to create vDPA devices a few years ago.
> >
> > When you get down to the operations they all seem pretty common sense
> > and straightfoward. Create an IOASID. Connect to a device. Fill the
> > IOASID with pages somehow. Worry about PASID labeling.
> >
> > It really is critical to get all the vendor IOMMU people to go over it
> > and see how their HW features map into this.
> >
>
> Agree. btw I feel it might be good to have several design opens
> centrally discussed after going through all the comments. Otherwise
> they may be buried in different sub-threads and potentially with
> insufficient care (especially for people who haven't completed the
> reading).
>
> I summarized five opens here, about:
>
> 1) Finalizing the name to replace /dev/ioasid;
> 2) Whether one device is allowed to bind to multiple IOASID fd's;
> 3) Carry device information in invalidation/fault reporting uAPI;
> 4) What should/could be specified when allocating an IOASID;
> 5) The protocol between vfio group and kvm;
>
> For 1), two alternative names are mentioned: /dev/iommu and
> /dev/ioas. I don't have a strong preference and would like to hear
> votes from all stakeholders. /dev/iommu is slightly better imho for
> two reasons. First, per AMD's presentation in last KVM forum they
> implement vIOMMU in hardware thus need to support user-managed
> domains. An iommu uAPI notation might make more sense moving
> forward. Second, it makes later uAPI naming easier as 'IOASID' can
> be always put as an object, e.g. IOMMU_ALLOC_IOASID instead of
> IOASID_ALLOC_IOASID. :)
I think two years ago I suggested /dev/iommu and it didn't go very far
at the time. We've also talked about this as /dev/sva for a while and
now /dev/ioasid
I think /dev/iommu is fine, and call the things inside them IOAS
objects.
Then we don't have naming aliasing with kernel constructs.
> For 2), Jason prefers to not blocking it if no kernel design reason. If
> one device is allowed to bind multiple IOASID fd's, the main problem
> is about cross-fd IOASID nesting, e.g. having gpa_ioasid created in fd1
> and giova_ioasid created in fd2 and then nesting them together (and
Huh? This can't happen
Creating an IOASID is an operation on on the /dev/ioasid FD. We won't
provide APIs to create a tree of IOASID's outside a single FD container.
If a device can consume multiple IOASID's it doesn't care how many or
what /dev/ioasid FDs they come from.
> To the other end there was also thought whether we should make
> a single I/O address space per IOASID fd. This was discussed in previous
> thread that #fd's are insufficient to afford theoretical 1M's address
> spaces per device. But let's have another revisit and draw a clear
> conclusion whether this option is viable.
I had remarks on this, I think per-fd doesn't work
> This implies that VFIO_BOUND_IOASID will be extended to allow user
> specify a device label. This label will be recorded in /dev/iommu to
> serve per-device invalidation request from and report per-device
> fault data to the user.
I wonder which of the user providing a 64 bit cookie or the kernel
returning a small IDA is the best choice here? Both have merits
depending on what qemu needs..
> In addition, vPASID (if provided by user) will
> be also recorded in /dev/iommu so vPASID<->pPASID conversion
> is conducted properly. e.g. invalidation request from user carries
> a vPASID which must be converted into pPASID before calling iommu
> driver. Vice versa for raw fault data which carries pPASID while the
> user expects a vPASID.
I don't think the PASID should be returned at all. It should return
the IOASID number in the FD and/or a u64 cookie associated with that
IOASID. Userspace should figure out what the IOASID & device
combination means.
> Seems to close this design open we have to touch the kAPI design. and
> Joerg's input is highly appreciated here.
uAPI is forever, the kAPI is constantly changing. I always dislike
warping the uAPI based on the current kAPI situation.
Jason
next prev parent reply other threads:[~2021-06-01 20:28 UTC|newest]
Thread overview: 258+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-27 7:58 [RFC] /dev/ioasid uAPI proposal Tian, Kevin
2021-05-28 2:24 ` Jason Wang
2021-05-28 20:25 ` Jason Gunthorpe
[not found] ` <20210531164118.265789ee@yiliu-dev>
2021-06-01 2:36 ` Jason Wang
2021-06-01 4:27 ` Shenming Lu
2021-06-01 5:10 ` Jason Wang
[not found] ` <20210601113152.6d09e47b@yiliu-dev>
2021-06-01 5:08 ` Jason Wang
2021-06-01 5:23 ` Lu Baolu
2021-06-01 5:29 ` Jason Wang
2021-06-01 5:42 ` Tian, Kevin
2021-06-01 6:07 ` Jason Wang
2021-06-01 6:16 ` Tian, Kevin
2021-06-01 8:47 ` Jason Wang
2021-06-01 17:31 ` Jason Gunthorpe
2021-06-02 8:54 ` Jason Wang
2021-06-02 17:21 ` Jason Gunthorpe
2021-06-07 13:30 ` Enrico Weigelt, metux IT consult
2021-06-07 18:01 ` Jason Gunthorpe
2021-06-08 10:45 ` Enrico Weigelt, metux IT consult
2021-06-10 2:16 ` Jason Wang
2021-06-08 1:10 ` Jason Wang
2021-06-08 13:20 ` Jason Gunthorpe
2021-06-10 2:00 ` Jason Wang
2021-06-10 4:03 ` Jason Wang
2021-06-10 11:47 ` Jason Gunthorpe
2021-06-11 5:43 ` Jason Wang
2021-06-01 17:29 ` Jason Gunthorpe
2021-06-02 8:58 ` Jason Wang
2021-05-28 16:23 ` Jean-Philippe Brucker
2021-05-28 20:16 ` Jason Gunthorpe
2021-06-01 7:50 ` Tian, Kevin
2021-05-28 17:35 ` Jason Gunthorpe
2021-06-01 8:10 ` Tian, Kevin
2021-06-01 17:42 ` Jason Gunthorpe
2021-06-02 1:33 ` Tian, Kevin
2021-06-02 16:09 ` Jason Gunthorpe
2021-06-03 1:29 ` Tian, Kevin
2021-06-03 5:09 ` David Gibson
2021-06-03 6:49 ` Tian, Kevin
2021-06-03 11:47 ` Jason Gunthorpe
2021-06-04 2:15 ` Tian, Kevin
2021-06-08 0:49 ` David Gibson
2021-06-09 2:52 ` Tian, Kevin
2021-06-02 6:32 ` David Gibson
2021-06-02 16:16 ` Jason Gunthorpe
2021-06-03 2:11 ` Tian, Kevin
2021-06-03 5:13 ` David Gibson
2021-06-03 11:52 ` Jason Gunthorpe
2021-06-08 0:53 ` David Gibson
2021-06-08 19:04 ` Jason Gunthorpe
2021-06-17 2:42 ` David Gibson
2021-05-28 19:58 ` Jason Gunthorpe
2021-06-01 8:38 ` Tian, Kevin
2021-06-01 17:56 ` Jason Gunthorpe
2021-06-02 2:00 ` Tian, Kevin
2021-06-02 6:57 ` David Gibson
2021-06-02 16:37 ` Jason Gunthorpe
2021-06-03 5:23 ` David Gibson
2021-06-03 12:28 ` Jason Gunthorpe
2021-06-08 6:04 ` David Gibson
2021-06-08 19:23 ` Jason Gunthorpe
2021-06-02 6:48 ` David Gibson
2021-06-02 16:58 ` Jason Gunthorpe
2021-06-03 2:49 ` Tian, Kevin
2021-06-03 5:48 ` David Gibson
2021-06-03 5:45 ` David Gibson
2021-06-03 12:11 ` Jason Gunthorpe
2021-06-04 6:08 ` Tian, Kevin
2021-06-04 12:33 ` Jason Gunthorpe
2021-06-04 23:20 ` Tian, Kevin
2021-06-08 6:13 ` David Gibson
2021-06-04 10:24 ` Jean-Philippe Brucker
2021-06-04 12:05 ` Jason Gunthorpe
2021-06-04 17:27 ` Jacob Pan
2021-06-04 17:40 ` Jason Gunthorpe
2021-06-08 6:31 ` David Gibson
2021-06-10 16:37 ` Jean-Philippe Brucker
2021-06-17 3:00 ` David Gibson
2021-06-18 17:03 ` Jean-Philippe Brucker
2021-06-18 18:30 ` Jason Gunthorpe
2021-06-23 8:19 ` Tian, Kevin
2021-06-23 7:57 ` Tian, Kevin
2021-06-24 3:49 ` David Gibson
2021-05-28 20:03 ` Jason Gunthorpe
2021-06-01 7:01 ` Tian, Kevin
2021-06-01 20:28 ` Jason Gunthorpe [this message]
2021-06-02 1:25 ` Tian, Kevin
2021-06-02 23:27 ` Jason Gunthorpe
2021-06-04 8:17 ` Jean-Philippe Brucker
2021-06-04 8:43 ` Tian, Kevin
2021-06-02 8:52 ` Jason Wang
2021-06-02 16:07 ` Jason Gunthorpe
2021-06-01 22:22 ` Alex Williamson
2021-06-02 2:20 ` Tian, Kevin
2021-06-02 16:01 ` Jason Gunthorpe
2021-06-02 17:11 ` Alex Williamson
2021-06-02 17:35 ` Jason Gunthorpe
2021-06-02 18:01 ` Alex Williamson
2021-06-02 18:09 ` Jason Gunthorpe
2021-06-02 19:00 ` Alex Williamson
2021-06-02 19:54 ` Jason Gunthorpe
2021-06-02 20:37 ` Alex Williamson
2021-06-02 22:45 ` Jason Gunthorpe
2021-06-03 2:50 ` Alex Williamson
2021-06-03 3:22 ` Tian, Kevin
2021-06-03 4:14 ` Alex Williamson
2021-06-03 5:18 ` Tian, Kevin
2021-06-03 12:40 ` Jason Gunthorpe
2021-06-03 20:41 ` Alex Williamson
2021-06-04 9:19 ` Tian, Kevin
2021-06-04 15:37 ` Alex Williamson
2021-06-04 12:13 ` Jason Gunthorpe
2021-06-04 21:45 ` Alex Williamson
2021-06-04 7:33 ` Tian, Kevin
2021-06-03 12:34 ` Jason Gunthorpe
2021-06-03 20:01 ` Alex Williamson
2021-06-03 20:10 ` Jason Gunthorpe
2021-06-03 21:44 ` Alex Williamson
2021-06-04 8:38 ` Tian, Kevin
2021-06-04 12:28 ` Jason Gunthorpe
2021-06-04 15:26 ` Alex Williamson
2021-06-04 15:40 ` Paolo Bonzini
2021-06-04 15:50 ` Jason Gunthorpe
2021-06-04 15:57 ` Paolo Bonzini
2021-06-04 16:03 ` Jason Gunthorpe
2021-06-04 16:10 ` Paolo Bonzini
2021-06-04 17:22 ` Jason Gunthorpe
2021-06-04 21:29 ` Alex Williamson
2021-06-04 23:01 ` Jason Gunthorpe
2021-06-07 15:41 ` Alex Williamson
2021-06-07 18:18 ` Jason Gunthorpe
2021-06-07 18:59 ` Alex Williamson
2021-06-07 19:08 ` Jason Gunthorpe
2021-06-07 19:41 ` Alex Williamson
2021-06-07 23:03 ` Jason Gunthorpe
2021-06-08 0:30 ` Alex Williamson
2021-06-08 1:20 ` Jason Wang
2021-06-30 6:53 ` Christoph Hellwig
2021-06-30 6:49 ` Christoph Hellwig
2021-06-07 3:25 ` Tian, Kevin
2021-06-07 6:51 ` Paolo Bonzini
2021-06-07 18:01 ` Jason Gunthorpe
2021-06-30 6:56 ` Christoph Hellwig
2021-06-05 6:22 ` Paolo Bonzini
2021-06-07 3:50 ` Tian, Kevin
2021-06-07 17:59 ` Jason Gunthorpe
2021-06-08 7:56 ` Paolo Bonzini
2021-06-08 13:15 ` Jason Gunthorpe
2021-06-08 13:44 ` Paolo Bonzini
2021-06-08 18:47 ` Alex Williamson
2021-06-08 19:00 ` Jason Gunthorpe
2021-06-09 8:51 ` Enrico Weigelt, metux IT consult
2021-06-09 9:11 ` Paolo Bonzini
2021-06-09 11:54 ` Jason Gunthorpe
2021-06-09 14:31 ` Alex Williamson
2021-06-09 14:45 ` Jason Gunthorpe
2021-06-09 15:20 ` Paolo Bonzini
2021-10-27 6:18 ` Tian, Kevin
2021-10-27 10:32 ` Paolo Bonzini
2021-10-28 1:50 ` Tian, Kevin
2021-06-09 2:49 ` Tian, Kevin
2021-06-09 11:57 ` Jason Gunthorpe
2021-06-09 12:46 ` Paolo Bonzini
2021-06-09 12:47 ` Jason Gunthorpe
2021-06-09 13:24 ` Paolo Bonzini
2021-06-09 14:32 ` Jason Gunthorpe
2021-06-30 7:01 ` Christoph Hellwig
2021-06-09 18:09 ` Alex Williamson
2021-06-03 2:52 ` Jason Wang
2021-06-03 13:09 ` Jason Gunthorpe
2021-06-04 1:11 ` Jason Wang
2021-06-04 11:58 ` Jason Gunthorpe
2021-06-07 3:18 ` Jason Wang
2021-06-07 14:14 ` Jason Gunthorpe
2021-06-08 1:00 ` Jason Wang
2021-06-08 8:54 ` Enrico Weigelt, metux IT consult
2021-06-08 12:52 ` Jason Gunthorpe
2021-06-30 7:07 ` Christoph Hellwig
2021-06-30 7:05 ` Christoph Hellwig
2021-06-08 2:37 ` David Gibson
2021-06-08 13:17 ` Jason Gunthorpe
2021-06-17 3:47 ` David Gibson
2021-06-23 7:59 ` Tian, Kevin
2021-06-24 3:53 ` David Gibson
2021-05-28 23:36 ` Jason Gunthorpe
2021-05-31 11:31 ` Liu Yi L
2021-05-31 18:09 ` Jason Gunthorpe
2021-06-01 3:08 ` Lu Baolu
2021-06-01 17:24 ` Jason Gunthorpe
2021-06-01 1:25 ` Lu Baolu
2021-06-01 11:09 ` Lu Baolu
2021-06-01 17:26 ` Jason Gunthorpe
2021-06-02 4:01 ` Lu Baolu
2021-06-02 23:23 ` Jason Gunthorpe
2021-06-03 5:49 ` Lu Baolu
2021-06-03 5:54 ` David Gibson
2021-06-03 6:50 ` Lu Baolu
2021-06-03 12:56 ` Jason Gunthorpe
2021-06-02 7:22 ` David Gibson
2021-06-03 6:39 ` Tian, Kevin
2021-06-03 13:05 ` Jason Gunthorpe
2021-06-04 6:37 ` Tian, Kevin
2021-06-04 12:09 ` Jason Gunthorpe
2021-06-04 23:10 ` Tian, Kevin
2021-06-07 17:54 ` Jason Gunthorpe
2021-06-15 8:59 ` Tian, Kevin
2021-06-15 15:06 ` Jason Gunthorpe
2021-06-15 22:59 ` Tian, Kevin
2021-06-15 23:02 ` Jason Gunthorpe
2021-06-15 23:09 ` Tian, Kevin
2021-06-15 23:40 ` Jason Gunthorpe
2021-06-15 23:56 ` Tian, Kevin
2021-06-15 23:59 ` Jason Gunthorpe
2021-06-16 0:02 ` Tian, Kevin
2021-05-31 17:37 ` Parav Pandit
2021-05-31 18:12 ` Jason Gunthorpe
2021-06-01 12:04 ` Parav Pandit
2021-06-01 17:36 ` Jason Gunthorpe
2021-06-02 8:38 ` Enrico Weigelt, metux IT consult
2021-06-02 12:41 ` Parav Pandit
2021-06-01 4:31 ` Shenming Lu
2021-06-01 5:10 ` Lu Baolu
2021-06-01 7:15 ` Shenming Lu
2021-06-01 12:30 ` Lu Baolu
2021-06-01 13:10 ` Shenming Lu
2021-06-01 17:33 ` Jason Gunthorpe
2021-06-02 4:50 ` Shenming Lu
2021-06-03 18:19 ` Jacob Pan
2021-06-04 1:30 ` Jason Wang
2021-06-04 16:22 ` Jacob Pan
2021-06-04 16:22 ` Jason Gunthorpe
2021-06-04 18:05 ` Jacob Pan
2021-06-04 2:03 ` Shenming Lu
2021-06-07 12:19 ` Liu, Yi L
2021-06-08 1:09 ` Shenming Lu
2021-06-01 17:30 ` Parav Pandit
2021-06-03 20:58 ` Jacob Pan
2021-06-08 6:30 ` Parav Pandit
2021-06-02 6:15 ` David Gibson
2021-06-02 17:19 ` Jason Gunthorpe
2021-06-03 3:02 ` Tian, Kevin
2021-06-03 6:26 ` David Gibson
2021-06-03 12:46 ` Jason Gunthorpe
2021-06-04 6:27 ` Tian, Kevin
2021-06-03 7:17 ` Tian, Kevin
2021-06-03 12:49 ` Jason Gunthorpe
2021-06-08 5:49 ` David Gibson
2021-06-03 8:12 ` Tian, Kevin
2021-06-17 4:07 ` David Gibson
2021-06-23 8:00 ` Tian, Kevin
2021-06-24 3:55 ` David Gibson
2021-06-02 8:56 ` Enrico Weigelt, metux IT consult
2021-06-02 17:24 ` Jason Gunthorpe
2021-06-04 10:44 ` Enrico Weigelt, metux IT consult
2021-06-04 12:30 ` Jason Gunthorpe
2021-06-08 1:15 ` David Gibson
2021-06-08 10:43 ` Enrico Weigelt, metux IT consult
2021-06-08 13:11 ` Jason Gunthorpe
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