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From: Lu Baolu <baolu.lu@linux.intel.com>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: baolu.lu@linux.intel.com, Robin Murphy <robin.murphy@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Joerg Roedel <joro@8bytes.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Christoph Hellwig <hch@infradead.org>,
	Kevin Tian <kevin.tian@intel.com>,
	Ashok Raj <ashok.raj@intel.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 v4 07/13] iommu: Add iommu_at[de]tach_device_shared() for multi-device groups
Date: Tue, 4 Jan 2022 09:53:47 +0800	[thread overview]
Message-ID: <1a22fecf-9cba-76f8-7dc4-88a56b2457cd@linux.intel.com> (raw)
In-Reply-To: <20211224025036.GD1779224@nvidia.com>

On 12/24/21 10:50 AM, Jason Gunthorpe wrote:
>>> We don't need _USER anymore because iommu_group_set_dma_owner() always
>>> does detatch, and iommu_replace_group_domain() avoids ever reassigning
>>> default_domain. The sepecial USER behavior falls out automatically.
>> This means we will grow more group-centric interfaces. My understanding
>> is the opposite that we should hide the concept of group in IOMMU
>> subsystem, and the device drivers only faces device specific interfaces.
> Ideally group interfaces would be reduced, but in this case VFIO needs
> the group. It has sort of a fundamental problem with its uAPI that
> expects the container is fully setup with a domain at the moment the
> group is attached. So deferring domain setup to when the device is
> available becomes a user visible artifact - and if this is important
> or not is a whole research question that isn't really that important
> for this series.
> 
> We also can't just pull a device out of thin air, a device that hasn't
> been probed() hasn't even had dma_configure called! Let alone the
> lifetime and locking problems with that kind of idea.
> 
> So.. leaving it as a group interface makes the most sense,
> particularly for this series which is really about fixing the sharing
> model in the iommu core and deleting the BUG_ONs.

I feel it makes more sense if we leave the attach_device/group
refactoring patches into a separated series. I will come up with this
new series so that people can review and comment on the real code.

Best regards,
baolu

  parent reply	other threads:[~2022-01-04  1:54 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-17  6:36 [PATCH v4 00/13] Fix BUG_ON in vfio_iommu_group_notifier() Lu Baolu
2021-12-17  6:36 ` [PATCH v4 01/13] iommu: Add device dma ownership set/release interfaces Lu Baolu
2021-12-17  6:36 ` [PATCH v4 02/13] driver core: Set DMA ownership during driver bind/unbind Lu Baolu
2021-12-22 12:47   ` Greg Kroah-Hartman
2021-12-22 17:52     ` Jason Gunthorpe
2021-12-23  2:08     ` Lu Baolu
2021-12-23  3:02     ` Lu Baolu
2021-12-23  7:13       ` Greg Kroah-Hartman
2021-12-23  7:23         ` Lu Baolu
2021-12-31  0:36           ` Jason Gunthorpe
2021-12-17  6:36 ` [PATCH v4 03/13] PCI: pci_stub: Suppress kernel DMA ownership auto-claiming Lu Baolu
2021-12-29 20:42   ` Bjorn Helgaas
2021-12-30  5:34     ` Lu Baolu
2021-12-30 22:24       ` Bjorn Helgaas
2021-12-31  0:40         ` Jason Gunthorpe
2021-12-31  1:10           ` Lu Baolu
2021-12-31  1:58             ` Lu Baolu
2022-01-03 19:53             ` Jason Gunthorpe
2022-01-04  1:54               ` Lu Baolu
2021-12-31  1:06         ` Lu Baolu
2021-12-17  6:36 ` [PATCH v4 04/13] PCI: portdrv: " Lu Baolu
2021-12-29 21:16   ` Bjorn Helgaas
2021-12-30  5:49     ` Lu Baolu
2021-12-17  6:37 ` [PATCH v4 05/13] iommu: Add security context management for assigned devices Lu Baolu
2021-12-17  6:37 ` [PATCH v4 06/13] iommu: Expose group variants of dma ownership interfaces Lu Baolu
2021-12-17  6:37 ` [PATCH v4 07/13] iommu: Add iommu_at[de]tach_device_shared() for multi-device groups Lu Baolu
2021-12-21 16:50   ` Robin Murphy
2021-12-21 18:46     ` Jason Gunthorpe
2021-12-22  4:22       ` Lu Baolu
2021-12-22  4:25         ` Lu Baolu
2021-12-22 20:26       ` Robin Murphy
2021-12-23  0:57         ` Jason Gunthorpe
2021-12-23  5:53           ` Lu Baolu
2021-12-23 14:03             ` Jason Gunthorpe
2021-12-24  1:30               ` Lu Baolu
2021-12-24  2:50                 ` Jason Gunthorpe
2021-12-24  6:44                   ` Lu Baolu
2022-01-04  1:53                   ` Lu Baolu [this message]
2021-12-24  3:19         ` Lu Baolu
2021-12-24 14:24           ` Jason Gunthorpe
2021-12-17  6:37 ` [PATCH v4 08/13] vfio: Set DMA USER ownership for VFIO devices Lu Baolu
2021-12-17  6:37 ` [PATCH v4 09/13] vfio: Remove use of vfio_group_viable() Lu Baolu
2021-12-17  6:37 ` [PATCH v4 10/13] vfio: Delete the unbound_list Lu Baolu
2021-12-17  6:37 ` [PATCH v4 11/13] vfio: Remove iommu group notifier Lu Baolu
2021-12-17  6:37 ` [PATCH v4 12/13] iommu: Remove iommu group changes notifier Lu Baolu
2021-12-17  6:37 ` [PATCH v4 13/13] drm/tegra: Use the iommu dma_owner mechanism Lu Baolu
2022-01-04  5:23 ` [PATCH v4 00/13] Fix BUG_ON in vfio_iommu_group_notifier() Lu Baolu

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