From: Joerg Roedel <joro@8bytes.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Stuart Yoder <stuyoder@gmail.com>,
rafael@kernel.org, David Airlie <airlied@linux.ie>,
linux-pci@vger.kernel.org,
Thierry Reding <thierry.reding@gmail.com>,
Diana Craciun <diana.craciun@oss.nxp.com>,
Dmitry Osipenko <digetx@gmail.com>, Will Deacon <will@kernel.org>,
Ashok Raj <ashok.raj@intel.com>,
Jonathan Hunter <jonathanh@nvidia.com>,
Christoph Hellwig <hch@infradead.org>,
Kevin Tian <kevin.tian@intel.com>,
Chaitanya Kulkarni <kch@nvidia.com>,
Alex Williamson <alex.williamson@redhat.com>,
kvm@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
Dan Williams <dan.j.williams@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Cornelia Huck <cohuck@redhat.com>,
linux-kernel@vger.kernel.org, Li Yang <leoyang.li@nxp.com>,
iommu@lists.linux-foundation.org,
Jacob jun Pan <jacob.jun.pan@intel.com>,
Daniel Vetter <daniel@ffwll.ch>,
Robin Murphy <robin.murphy@arm.com>
Subject: Re: [PATCH v1 3/8] iommu: Extend iommu_at[de]tach_device() for multi-device groups
Date: Mon, 14 Feb 2022 15:39:53 +0100 [thread overview]
Message-ID: <Ygppub+Wjq6mQEAX@8bytes.org> (raw)
In-Reply-To: <20220214130313.GV4160@nvidia.com>
On Mon, Feb 14, 2022 at 09:03:13AM -0400, Jason Gunthorpe wrote:
> Groups should disappear into an internal implementation detail, not be
> so prominent in the API.
Not going to happen, IOMMU groups are ABI and todays device assignment
code, including user-space, relies on them.
Groups implement and important aspect of hardware IOMMUs that the API
can not abstract away: That there are devices which share the same
request-id.
This is not an issue for devices concerned by iommufd, but for legacy
device assignment it is. The IOMMU-API needs to handle both in a clean
API, even if it means that drivers need to lookup the sub-group of a
device first.
And I don't see how a per-device API can handle both in a device-centric
way. For sure it is not making it 'device centric but operate on groups
under the hood'.
Regards,
Joerg
_______________________________________________
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iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu
WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <joro@8bytes.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@infradead.org>,
Kevin Tian <kevin.tian@intel.com>,
Ashok Raj <ashok.raj@intel.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Will Deacon <will@kernel.org>,
Dan Williams <dan.j.williams@intel.com>,
rafael@kernel.org, Diana Craciun <diana.craciun@oss.nxp.com>,
Cornelia Huck <cohuck@redhat.com>,
Eric Auger <eric.auger@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
Jacob jun Pan <jacob.jun.pan@intel.com>,
Chaitanya Kulkarni <kch@nvidia.com>,
Stuart Yoder <stuyoder@gmail.com>,
Laurentiu Tudor <laurentiu.tudor@nxp.com>,
Thierry Reding <thierry.reding@gmail.com>,
David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
Jonathan Hunter <jonathanh@nvidia.com>,
Li Yang <leoyang.li@nxp.com>, Dmitry Osipenko <digetx@gmail.com>,
iommu@lists.linux-foundation.org, linux-pci@vger.kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1 3/8] iommu: Extend iommu_at[de]tach_device() for multi-device groups
Date: Mon, 14 Feb 2022 15:39:53 +0100 [thread overview]
Message-ID: <Ygppub+Wjq6mQEAX@8bytes.org> (raw)
In-Reply-To: <20220214130313.GV4160@nvidia.com>
On Mon, Feb 14, 2022 at 09:03:13AM -0400, Jason Gunthorpe wrote:
> Groups should disappear into an internal implementation detail, not be
> so prominent in the API.
Not going to happen, IOMMU groups are ABI and todays device assignment
code, including user-space, relies on them.
Groups implement and important aspect of hardware IOMMUs that the API
can not abstract away: That there are devices which share the same
request-id.
This is not an issue for devices concerned by iommufd, but for legacy
device assignment it is. The IOMMU-API needs to handle both in a clean
API, even if it means that drivers need to lookup the sub-group of a
device first.
And I don't see how a per-device API can handle both in a device-centric
way. For sure it is not making it 'device centric but operate on groups
under the hood'.
Regards,
Joerg
next prev parent reply other threads:[~2022-02-14 14:40 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-06 2:20 [PATCH v1 0/8] Scrap iommu_attach/detach_group() interfaces Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 2:20 ` [PATCH v1 1/8] iommu: Add iommu_group_replace_domain() Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 17:06 ` Jason Gunthorpe via iommu
2022-01-06 17:06 ` Jason Gunthorpe
2022-01-07 0:26 ` Lu Baolu
2022-01-07 0:26 ` Lu Baolu
2022-02-14 12:09 ` Robin Murphy
2022-02-14 12:09 ` Robin Murphy
2022-02-14 12:45 ` Jason Gunthorpe via iommu
2022-02-14 12:45 ` Jason Gunthorpe
2022-02-14 14:10 ` Robin Murphy
2022-02-14 14:10 ` Robin Murphy
2022-02-14 14:56 ` Jason Gunthorpe via iommu
2022-02-14 14:56 ` Jason Gunthorpe
2022-02-14 16:38 ` Robin Murphy
2022-02-14 16:38 ` Robin Murphy
2022-02-14 17:25 ` Jason Gunthorpe via iommu
2022-02-14 17:25 ` Jason Gunthorpe
2022-01-06 2:20 ` [PATCH v1 2/8] vfio/type1: Use iommu_group_replace_domain() Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 2:20 ` [PATCH v1 3/8] iommu: Extend iommu_at[de]tach_device() for multi-device groups Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 17:22 ` Jason Gunthorpe via iommu
2022-01-06 17:22 ` Jason Gunthorpe
2022-01-07 1:14 ` Lu Baolu
2022-01-07 1:14 ` Lu Baolu
2022-01-07 1:19 ` Jason Gunthorpe via iommu
2022-01-07 1:19 ` Jason Gunthorpe
2022-02-14 11:39 ` Joerg Roedel
2022-02-14 11:39 ` Joerg Roedel
2022-02-14 13:03 ` Jason Gunthorpe via iommu
2022-02-14 13:03 ` Jason Gunthorpe
2022-02-14 14:39 ` Joerg Roedel [this message]
2022-02-14 14:39 ` Joerg Roedel
2022-02-14 15:18 ` Robin Murphy
2022-02-14 15:18 ` Robin Murphy
2022-02-14 15:46 ` Jason Gunthorpe via iommu
2022-02-14 15:46 ` Jason Gunthorpe
2022-02-15 8:58 ` Joerg Roedel
2022-02-15 8:58 ` Joerg Roedel
2022-02-15 13:47 ` Jason Gunthorpe via iommu
2022-02-15 13:47 ` Jason Gunthorpe
2022-02-16 6:28 ` Lu Baolu
2022-02-16 6:28 ` Lu Baolu
2022-02-16 13:54 ` Jason Gunthorpe via iommu
2022-02-16 13:54 ` Jason Gunthorpe
2022-01-06 2:20 ` [PATCH v1 4/8] drm/tegra: Use iommu_attach/detatch_device() Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 2:20 ` [PATCH v1 5/8] iommu/amd: Use iommu_attach/detach_device() Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 14:33 ` Jason Gunthorpe via iommu
2022-01-06 14:33 ` Jason Gunthorpe
2022-01-07 0:23 ` Lu Baolu
2022-01-07 0:23 ` Lu Baolu
2022-02-14 11:27 ` Joerg Roedel
2022-02-14 11:27 ` Joerg Roedel
2022-02-14 13:15 ` Jason Gunthorpe via iommu
2022-02-14 13:15 ` Jason Gunthorpe
2022-02-14 13:40 ` Joerg Roedel
2022-02-14 13:40 ` Joerg Roedel
2022-02-14 14:02 ` Jason Gunthorpe via iommu
2022-02-14 14:02 ` Jason Gunthorpe
2022-02-14 14:23 ` Joerg Roedel
2022-02-14 14:23 ` Joerg Roedel
2022-02-14 15:00 ` Jason Gunthorpe via iommu
2022-02-14 15:00 ` Jason Gunthorpe
2022-02-15 9:11 ` Joerg Roedel
2022-02-15 9:11 ` Joerg Roedel
2022-02-15 13:02 ` Robin Murphy
2022-02-15 13:02 ` Robin Murphy
2022-02-15 14:37 ` Jason Gunthorpe via iommu
2022-02-15 14:37 ` Jason Gunthorpe
2022-01-06 2:20 ` [PATCH v1 6/8] gpu/host1x: " Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 15:35 ` Jason Gunthorpe via iommu
2022-01-06 15:35 ` Jason Gunthorpe
2022-01-07 0:35 ` Lu Baolu
2022-01-07 0:35 ` Lu Baolu
2022-01-07 0:48 ` Jason Gunthorpe via iommu
2022-01-07 0:48 ` Jason Gunthorpe
2022-01-07 1:19 ` Lu Baolu
2022-01-07 1:19 ` Lu Baolu
2022-01-06 2:20 ` [PATCH v1 7/8] media: staging: media: tegra-vde: " Lu Baolu
2022-01-06 2:20 ` Lu Baolu
2022-01-06 2:20 ` [PATCH v1 8/8] iommu: Remove iommu_attach/detach_group() Lu Baolu
2022-01-06 2:20 ` Lu Baolu
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