From: "Tian, Kevin" <kevin.tian@intel.com>
To: Baolu Lu <baolu.lu@linux.intel.com>, Jason Gunthorpe <jgg@nvidia.com>
Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>,
"Jiang, Dave" <dave.jiang@intel.com>,
"Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
Jean-Philippe Brucker <jean-philippe@linaro.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@infradead.org>,
Vinod Koul <vkoul@kernel.org>,
"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
Robin Murphy <robin.murphy@arm.com>
Subject: RE: [PATCH v6 03/12] iommu: Add attach/detach_dev_pasid domain ops
Date: Wed, 11 May 2022 04:09:14 +0000 [thread overview]
Message-ID: <BN9PR11MB5276100AC9BBB7DE5CB800CF8CC89@BN9PR11MB5276.namprd11.prod.outlook.com> (raw)
In-Reply-To: <f56ea479-aa82-37ae-91c3-754816a4ed8b@linux.intel.com>
> From: Baolu Lu <baolu.lu@linux.intel.com>
> Sent: Wednesday, May 11, 2022 10:32 AM
>
> On 2022/5/10 22:02, Jason Gunthorpe wrote:
> > On Tue, May 10, 2022 at 02:17:29PM +0800, Lu Baolu wrote:
> >
> >> This adds a pair of common domain ops for this purpose and adds
> helpers
> >> to attach/detach a domain to/from a {device, PASID}.
> >
> > I wonder if this should not have a detach op - after discussing with
> > Robin we can see that detach_dev is not used in updated
> > drivers. Instead attach_dev acts as 'set_domain'
> >
> > So, it would be more symmetrical if attaching a blocking_domain to the
> > PASID was the way to 'detach'.
> >
> > This could be made straightforward by following the sketch I showed to
> > have a static, global blocing_domain and providing a pointer to it in
> > struct iommu_ops
> >
> > Then 'detach pasid' is:
> >
> > iommu_ops->blocking_domain->ops->attach_dev_pasid(domain, dev,
> pasid);
> >
> > And we move away from the notion of 'detach' and in the direction that
> > everything continuously has a domain set. PASID would logically
> > default to blocking_domain, though we wouldn't track this anywhere.
>
> I am not sure whether we still need to keep the blocking domain concept
> when we are entering the new PASID world. Please allow me to wait and
> listen to more opinions.
>
I'm with Jason on this direction. In concept after a PASID is detached it's
essentially blocked. Implementation-wise it doesn't prevent the iommu
driver from marking the PASID entry as non-present as doing in this
series instead of actually pointing to the empty page table of the block
domain. But api-wise it does make the entire semantics more consistent.
Thanks
Kevin
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next prev parent reply other threads:[~2022-05-11 4:09 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-10 6:17 [PATCH v6 00/12] iommu: SVA and IOPF refactoring Lu Baolu
2022-05-10 6:17 ` [PATCH v6 01/12] dmaengine: idxd: Separate user and kernel pasid enabling Lu Baolu
2022-05-10 6:17 ` [PATCH v6 02/12] iommu: Add pasid_bits field in struct dev_iommu Lu Baolu
2022-05-10 14:34 ` Jason Gunthorpe via iommu
2022-05-11 2:25 ` Baolu Lu
2022-05-11 8:00 ` Jean-Philippe Brucker
2022-05-11 11:59 ` Jason Gunthorpe via iommu
2022-05-10 6:17 ` [PATCH v6 03/12] iommu: Add attach/detach_dev_pasid domain ops Lu Baolu
2022-05-10 14:02 ` Jason Gunthorpe via iommu
2022-05-11 2:32 ` Baolu Lu
2022-05-11 4:09 ` Tian, Kevin [this message]
2022-05-11 7:54 ` Jean-Philippe Brucker
2022-05-11 12:02 ` Jason Gunthorpe via iommu
2022-05-12 7:00 ` Jean-Philippe Brucker
2022-05-12 11:51 ` Jason Gunthorpe via iommu
2022-05-16 2:03 ` Baolu Lu
2022-05-10 6:17 ` [PATCH v6 04/12] iommu/sva: Basic data structures for SVA Lu Baolu
2022-05-10 6:17 ` [PATCH v6 05/12] iommu/vt-d: Remove SVM_FLAG_SUPERVISOR_MODE support Lu Baolu
2022-05-10 14:35 ` Jason Gunthorpe via iommu
2022-05-10 6:17 ` [PATCH v6 06/12] iommu/vt-d: Add SVA domain support Lu Baolu
2022-05-10 6:17 ` [PATCH v6 07/12] arm-smmu-v3/sva: " Lu Baolu
2022-05-10 6:17 ` [PATCH v6 08/12] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces Lu Baolu
2022-05-10 15:23 ` Jason Gunthorpe via iommu
2022-05-11 7:21 ` Baolu Lu
2022-05-11 14:53 ` Jason Gunthorpe via iommu
2022-05-12 3:02 ` Baolu Lu
2022-05-12 5:01 ` Tian, Kevin
2022-05-12 5:17 ` Baolu Lu
2022-05-12 5:44 ` Tian, Kevin
2022-05-12 6:16 ` Baolu Lu
2022-05-12 11:48 ` Jason Gunthorpe via iommu
2022-05-12 11:59 ` Baolu Lu
2022-05-12 12:03 ` Jason Gunthorpe via iommu
2022-05-12 12:47 ` Baolu Lu
2022-05-12 11:51 ` Jason Gunthorpe via iommu
2022-05-12 12:39 ` Baolu Lu
2022-05-10 6:17 ` [PATCH v6 09/12] iommu: Remove SVA related callbacks from iommu ops Lu Baolu
2022-05-10 6:17 ` [PATCH v6 10/12] iommu: Prepare IOMMU domain for IOPF Lu Baolu
2022-05-10 6:17 ` [PATCH v6 11/12] iommu: Per-domain I/O page fault handling Lu Baolu
2022-05-10 6:17 ` [PATCH v6 12/12] iommu: Rename iommu-sva-lib.{c,h} Lu Baolu
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