From: Robin Murphy <robin.murphy-5wv7dgnIgG8@public.gmane.org>
To: "Tian,
Kevin" <kevin.tian-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
Jean-Philippe Brucker
<jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>,
"iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org"
<iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org>
Cc: "rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org"
<rafael-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
"gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org"
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
"will.deacon-5wv7dgnIgG8@public.gmane.org"
<will.deacon-5wv7dgnIgG8@public.gmane.org>,
"christian.koenig-5C7GfCeVMHo@public.gmane.org"
<christian.koenig-5C7GfCeVMHo@public.gmane.org>,
"alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org"
<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Subject: Re: [RFC PATCH 0/6] Auxiliary IOMMU domains and Arm SMMUv3
Date: Mon, 22 Oct 2018 12:50:56 +0100 [thread overview]
Message-ID: <11f88122-afd3-a34c-3cd4-db681bf5498b@arm.com> (raw)
In-Reply-To: <AADFC41AFE54684AB9EE6CBC0274A5D19BE0E176-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
On 22/10/2018 07:53, Tian, Kevin wrote:
>> From: Jean-Philippe Brucker [mailto:jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org]
>> Sent: Saturday, October 20, 2018 2:12 AM
>>
>> This is a first prototype adding auxiliary domain support to Arm SMMUv3,
>> following Lu Baolu's latest proposal for IOMMU aware mediated devices
>> [1]. It works, but the attach() API still doesn't feel right. See (2)
>> below.
>>
>> Patch 1 adapts iommu.c to the current proposal for auxiliary domains.
>> Patches 2-4 rework the PASID allocator to make it usable for SVA and
>> AUXD simultaneously. Patches 5-6 add AUXD support to SMMUv3.
>>
>>
>> When a device can have multiple address space, for instance with PCI
>> PASID, an auxiliary domain (AUXD) is the IOMMU representation of one
>> address space. I distinguish auxiliary from "main" domain, which
>> represents the non-PASID address space but also (at least for SMMUv3)
>> the whole device context, PASID tables etc.
>
> I'd like to clarify a bit. :-)
>
> a domain can always represent one or more address spaces, where an
> address space could be for IOVA or GPA and/or other address spaces for
> SVA. Address spaces may be chained together in so-called nested mode.
>
> a domain can be associated with a full device (in BDF granular), and/or
> with a partition of a device (say in PASID granular). In the former case,
> the domain becomes the master (or primary) domain of the device. In
> the latter case, the domain becomes the auxiliary domain of the device.
>
> vendor domain structure may include vendor-specific states which
> are applied to device context at attach time, e.g. PASID table (SMMUv3)
> if representing as master domain, or PASID value (VT-d scalable mode)
> if representing as auxiliary domain.
>
> so the domain definition is never changed with the introduction of
> AUXD. 'auxiliary' is a per-device attribute which takes effect when at
> domain attach time. A domain is perfectly sane to represent as a
> master domain to deviceA and an auxiliary domain to deviceB at the
> same time (say when device A and a mdev on deviceB are assigned to
> same VM), while supporting one or more address spaces.
To me, that sounds like a very good argument for having separate "attach
as primary domain" and "attach as aux domain" APIs. Say a driver wants
to use multiple aux domains itself to isolate logically-separate
transaction streams, but still also needs to control the main domain for
transactions without PASID (interrupts?) - having to juggle some
invisible device state around multiple iommu_{attach,detach}_group()
calls which look identical but are expected to behave differently at
runtime sounds like a recipe for unmaintainable code.
I don't think it's necessarily safe to assume that
one-struct-device-per-PASID will be the only usage model.
Robin.
next prev parent reply other threads:[~2018-10-22 11:50 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-19 18:11 [RFC PATCH 0/6] Auxiliary IOMMU domains and Arm SMMUv3 Jean-Philippe Brucker
[not found] ` <20181019181158.2395-1-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-19 18:11 ` [RFC PATCH 1/6] iommu: Adapt attach/detach_dev() for auxiliary domains Jean-Philippe Brucker
[not found] ` <20181019181158.2395-2-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-22 2:32 ` Lu Baolu
2018-10-19 18:11 ` [RFC PATCH 2/6] drivers core: Add I/O ASID allocator Jean-Philippe Brucker
[not found] ` <20181019181158.2395-3-jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>
2018-10-22 4:49 ` Lu Baolu
[not found] ` <9c6cd6c1-3569-4251-8344-fc9df0e743bc-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-10-22 10:22 ` Raj, Ashok
[not found] ` <20181022102254.GA25399-7RUrO8UaCDyr4tA6zuQqW9h3ngVCH38I@public.gmane.org>
2018-10-23 6:56 ` Lu Baolu
[not found] ` <02006e4f-2acf-6ff8-b695-c54c99509b46-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-10-23 22:13 ` Tian, Kevin
2018-11-07 4:53 ` Lu Baolu
[not found] ` <fb2bd5fe-5742-fcd8-b8f0-1885040e8d4f-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-08 18:51 ` Jean-Philippe Brucker
2018-11-12 14:40 ` Joerg Roedel
[not found] ` <20181112144039.GA25808-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-21 11:16 ` Jean-Philippe Brucker
[not found] ` <8f17757a-c657-aab9-a6a0-fb0cc9c610a8-5wv7dgnIgG8@public.gmane.org>
2018-11-21 19:10 ` Koenig, Christian
[not found] ` <62f05552-df46-6e12-10ed-820429dfda59-5C7GfCeVMHo@public.gmane.org>
2018-11-22 6:59 ` Tian, Kevin
2018-11-22 8:38 ` Joerg Roedel
2018-11-22 8:44 ` Joerg Roedel
[not found] ` <20181122084429.GB1586-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-22 11:17 ` Jean-Philippe Brucker
2018-10-19 18:11 ` [RFC PATCH 3/6] iommu/sva: Use external PASID allocator Jean-Philippe Brucker
2018-10-19 18:11 ` [RFC PATCH 4/6] iommu/sva: Support AUXD feature Jean-Philippe Brucker
2018-10-19 18:11 ` [RFC PATCH 5/6] iommu/arm-smmu-v3: Implement detach_dev op Jean-Philippe Brucker
2018-10-19 18:11 ` [RFC PATCH 6/6] iommu/arm-smmu-v3: Add support for auxiliary domains Jean-Philippe Brucker
2018-10-20 3:36 ` [RFC PATCH 0/6] Auxiliary IOMMU domains and Arm SMMUv3 Xu Zaibo
2018-10-22 6:53 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE0E176-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-10-22 11:50 ` Robin Murphy [this message]
[not found] ` <11f88122-afd3-a34c-3cd4-db681bf5498b-5wv7dgnIgG8@public.gmane.org>
2018-10-22 15:35 ` Jordan Crouse
2018-10-22 18:01 ` Jean-Philippe Brucker
2018-11-06 16:25 ` joro-zLv9SwRftAIdnm+yROfE0A
[not found] ` <20181106162539.4gmkvg57mja3bn7k-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-07 3:40 ` Lu Baolu
[not found] ` <e22e3631-2ecb-664d-5666-8e0f865dec83-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-07 16:43 ` joro-zLv9SwRftAIdnm+yROfE0A
[not found] ` <20181107164323.GA19831-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-07 17:23 ` Alex Williamson
2018-11-21 4:40 ` Lu Baolu
[not found] ` <758bb120-5bc0-1e2d-ccd0-9be0bcc5d8bc-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-11-23 11:21 ` joro-zLv9SwRftAIdnm+yROfE0A
[not found] ` <20181123112125.GF1586-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-25 6:51 ` Lu Baolu
2018-11-26 3:01 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE68777@SHSMSX101.ccr.corp.intel.com>
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE68777-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-11-26 7:29 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE689B8-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-07 10:29 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
[not found] ` <20181207102926.GM16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-10 2:06 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE95394-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-10 8:57 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
[not found] ` <20181210085745.GN16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-11 18:34 ` Jean-Philippe Brucker
[not found] ` <4be63d12-fa1c-b180-761b-5e8ceed58545-5wv7dgnIgG8@public.gmane.org>
2018-12-12 9:22 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
2018-12-12 9:31 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE9D6CA-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-12-12 9:54 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
[not found] ` <20181212095403.GU16835-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-12-12 10:03 ` Tian, Kevin
2018-12-10 2:57 ` Lu Baolu
[not found] ` <bf1ee4a3-6d3f-e0db-a02a-1db819843a60-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2018-12-10 8:59 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
2018-12-11 13:35 ` Jean-Philippe Brucker
[not found] ` <fc173d9f-57e2-dd87-95d0-1c615f2e14e3-5wv7dgnIgG8@public.gmane.org>
2018-12-12 9:29 ` 'joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org'
2018-11-08 18:29 ` Jean-Philippe Brucker
[not found] ` <42949d93-e22c-dd4d-cd49-46efc0b73cdb-5wv7dgnIgG8@public.gmane.org>
2018-11-12 14:55 ` joro-zLv9SwRftAIdnm+yROfE0A
[not found] ` <20181112145541.GB25808-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2018-11-21 19:05 ` Jean-Philippe Brucker
[not found] ` <5dcf9238-62b2-8df6-b378-183ee09c5951-5wv7dgnIgG8@public.gmane.org>
2018-11-23 12:50 ` joro-zLv9SwRftAIdnm+yROfE0A
2018-11-22 8:39 ` Tian, Kevin
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19BE5A7A7-0J0gbvR4kThpB2pF5aRoyrfspsVTdybXVpNB7YpNyf8@public.gmane.org>
2018-11-23 12:14 ` joro-zLv9SwRftAIdnm+yROfE0A
2018-10-22 10:07 ` Raj, Ashok
[not found] ` <20181021194426.GA11201-7RUrO8UaCDyr4tA6zuQqW9h3ngVCH38I@public.gmane.org>
2018-10-22 16:03 ` Jean-Philippe Brucker
[not found] ` <d45c5222-68e9-1d6e-730b-bb8dbc060586-5wv7dgnIgG8@public.gmane.org>
2018-10-23 17:16 ` Raj, Ashok
[not found] ` <1540314963.21962.20.camel-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
2018-10-23 22:08 ` Tian, Kevin
2018-10-26 3:00 ` Lu Baolu
2018-10-22 16:48 ` Jordan Crouse
[not found] ` <20181022164834.GH26762-9PYrDHPZ2Orvke4nUoYGnHL1okKdlPRT@public.gmane.org>
2018-11-02 3:19 ` Lu Baolu
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