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From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>,
	Joerg Roedel <joro@8bytes.org>, Jason Gunthorpe <jgg@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	"Raj, Ashok" <ashok.raj@intel.com>, Will Deacon <will@kernel.org>,
	Robin Murphy <robin.murphy@arm.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	Eric Auger <eric.auger@redhat.com>,
	"Liu, Yi L" <yi.l.liu@intel.com>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic
Date: Mon, 21 Mar 2022 11:42:16 +0000	[thread overview]
Message-ID: <YjhkmDEGwF4EcM8R@myrica> (raw)
In-Reply-To: <BL1PR11MB5271DE11A868204D2E0D5B548C169@BL1PR11MB5271.namprd11.prod.outlook.com>

Hi Kevin,

On Mon, Mar 21, 2022 at 08:09:36AM +0000, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@linux.intel.com>
> > Sent: Sunday, March 20, 2022 2:40 PM
> > 
> > The existing IOPF handling framework only handles the I/O page faults for
> > SVA. Ginven that we are able to link iommu domain with each I/O page fault,
> > we can now make the I/O page fault handling framework more general for
> > more types of page faults.
> 
> "make ... generic" in subject line is kind of confusing. Reading this patch I
> think you really meant changing from per-device fault handling to per-domain
> fault handling. This is more accurate in concept since the fault is caused by
> the domain page table. 😊

I tend to disagree with that last part. The fault is caused by a specific
device accessing shared page tables. We should keep that device
information throughout the fault handling, so that we can report it to the
driver when things go wrong. A process can have multiple threads bound to
different devices, they share the same mm so if the driver wanted to
signal a misbehaving thread, similarly to a SEGV on the CPU side, it would
need the device information to precisely report it to userspace.

Thanks,
Jean

WARNING: multiple messages have this Message-ID (diff)
From: Jean-Philippe Brucker <jean-philippe@linaro.org>
To: "Tian, Kevin" <kevin.tian@intel.com>
Cc: "Raj, Ashok" <ashok.raj@intel.com>,
	Robin Murphy <robin.murphy@arm.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Jean-Philippe Brucker <jean-philippe@linaro.com>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"Pan, Jacob jun" <jacob.jun.pan@intel.com>,
	Jason Gunthorpe <jgg@nvidia.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic
Date: Mon, 21 Mar 2022 11:42:16 +0000	[thread overview]
Message-ID: <YjhkmDEGwF4EcM8R@myrica> (raw)
In-Reply-To: <BL1PR11MB5271DE11A868204D2E0D5B548C169@BL1PR11MB5271.namprd11.prod.outlook.com>

Hi Kevin,

On Mon, Mar 21, 2022 at 08:09:36AM +0000, Tian, Kevin wrote:
> > From: Lu Baolu <baolu.lu@linux.intel.com>
> > Sent: Sunday, March 20, 2022 2:40 PM
> > 
> > The existing IOPF handling framework only handles the I/O page faults for
> > SVA. Ginven that we are able to link iommu domain with each I/O page fault,
> > we can now make the I/O page fault handling framework more general for
> > more types of page faults.
> 
> "make ... generic" in subject line is kind of confusing. Reading this patch I
> think you really meant changing from per-device fault handling to per-domain
> fault handling. This is more accurate in concept since the fault is caused by
> the domain page table. 😊

I tend to disagree with that last part. The fault is caused by a specific
device accessing shared page tables. We should keep that device
information throughout the fault handling, so that we can report it to the
driver when things go wrong. A process can have multiple threads bound to
different devices, they share the same mm so if the driver wanted to
signal a misbehaving thread, similarly to a SEGV on the CPU side, it would
need the device information to precisely report it to userspace.

Thanks,
Jean
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

  reply	other threads:[~2022-03-21 11:42 UTC|newest]

Thread overview: 112+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-20  6:40 [PATCH RFC 00/11] iommu: SVA and IOPF refactoring Lu Baolu
2022-03-20  6:40 ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 01/11] iommu: Add pasid_bits field in struct dev_iommu Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  7:01   ` Tian, Kevin
2022-03-21  7:01     ` Tian, Kevin
2022-03-21 10:22     ` Lu Baolu
2022-03-21 10:22       ` Lu Baolu
2022-03-22  0:26       ` Tian, Kevin
2022-03-22  0:26         ` Tian, Kevin
2022-03-22  0:48         ` Lu Baolu
2022-03-22  0:48           ` Lu Baolu
2022-03-21 11:22   ` Jean-Philippe Brucker
2022-03-21 11:22     ` Jean-Philippe Brucker
2022-03-22  0:45     ` Lu Baolu
2022-03-22  0:45       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 02/11] iommu: Add iommu_domain type for SVA Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  7:06   ` Tian, Kevin
2022-03-21  7:06     ` Tian, Kevin
2022-03-21 10:23     ` Lu Baolu
2022-03-21 10:23       ` Lu Baolu
2022-03-21 11:47   ` Jason Gunthorpe
2022-03-21 11:47     ` Jason Gunthorpe via iommu
2022-03-22  0:54     ` Lu Baolu
2022-03-22  0:54       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 03/11] iommu: Add attach/detach_dev_pasid domain ops Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  7:13   ` Tian, Kevin
2022-03-21  7:13     ` Tian, Kevin
2022-03-21 10:27     ` Lu Baolu
2022-03-21 10:27       ` Lu Baolu
2022-03-21 11:53     ` Jason Gunthorpe via iommu
2022-03-21 11:53       ` Jason Gunthorpe
2022-03-20  6:40 ` [PATCH RFC 04/11] iommu/vt-d: Add SVA domain support Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  7:45   ` Tian, Kevin
2022-03-21  7:45     ` Tian, Kevin
2022-03-21 10:37     ` Lu Baolu
2022-03-21 10:37       ` Lu Baolu
2022-03-21 11:56   ` Jason Gunthorpe via iommu
2022-03-21 11:56     ` Jason Gunthorpe
2022-03-22  4:25     ` Lu Baolu
2022-03-22  4:25       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 05/11] arm-smmu-v3/sva: " Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21 11:31   ` Jean-Philippe Brucker
2022-03-21 11:31     ` Jean-Philippe Brucker
2022-03-21 11:58     ` Jason Gunthorpe
2022-03-21 11:58       ` Jason Gunthorpe via iommu
2022-03-20  6:40 ` [PATCH RFC 06/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  8:04   ` Tian, Kevin
2022-03-21  8:04     ` Tian, Kevin
2022-03-21 11:01     ` Lu Baolu
2022-03-21 11:01       ` Lu Baolu
2022-03-21 12:03       ` Jason Gunthorpe
2022-03-21 12:03         ` Jason Gunthorpe via iommu
2022-03-21 11:33   ` Jean-Philippe Brucker
2022-03-21 11:33     ` Jean-Philippe Brucker
2022-03-22  4:29     ` Lu Baolu
2022-03-22  4:29       ` Lu Baolu
2022-03-21 12:05   ` Jason Gunthorpe
2022-03-21 12:05     ` Jason Gunthorpe via iommu
2022-03-22  4:31     ` Lu Baolu
2022-03-22  4:31       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 07/11] iommu: Remove SVA related callbacks from iommu ops Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 08/11] iommu: Handle IO page faults directly Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21 11:35   ` Jean-Philippe Brucker
2022-03-21 11:35     ` Jean-Philippe Brucker
2022-03-22  0:39     ` Tian, Kevin
2022-03-22  0:39       ` Tian, Kevin
2022-03-20  6:40 ` [PATCH RFC 09/11] iommu: Add iommu_get_domain_for_dev_pasid() Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21 12:40   ` Jason Gunthorpe
2022-03-21 12:40     ` Jason Gunthorpe via iommu
2022-03-22  4:50     ` Lu Baolu
2022-03-22  4:50       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 10/11] iommu: Make IOPF handling framework generic Lu Baolu
2022-03-20  6:40   ` Lu Baolu
2022-03-21  8:09   ` Tian, Kevin
2022-03-21  8:09     ` Tian, Kevin
2022-03-21 11:42     ` Jean-Philippe Brucker [this message]
2022-03-21 11:42       ` Jean-Philippe Brucker
2022-03-21 12:43       ` Jason Gunthorpe
2022-03-21 12:43         ` Jason Gunthorpe via iommu
2022-03-22  5:03         ` Lu Baolu
2022-03-22  5:03           ` Lu Baolu
2022-03-22 10:02           ` Jean-Philippe Brucker
2022-03-22 10:02             ` Jean-Philippe Brucker
2022-03-22 12:15           ` Jason Gunthorpe
2022-03-22 12:15             ` Jason Gunthorpe via iommu
2022-03-22  1:00       ` Tian, Kevin
2022-03-22  1:00         ` Tian, Kevin
2022-03-22 10:06         ` Jean-Philippe Brucker
2022-03-22 10:06           ` Jean-Philippe Brucker
2022-03-22 10:24           ` Tian, Kevin
2022-03-22 10:24             ` Tian, Kevin
2022-03-22 10:50             ` Jean-Philippe Brucker
2022-03-22 10:50               ` Jean-Philippe Brucker
2022-03-21 11:39   ` Jean-Philippe Brucker
2022-03-21 11:39     ` Jean-Philippe Brucker
2022-03-22  5:28     ` Lu Baolu
2022-03-22  5:28       ` Lu Baolu
2022-03-21 12:50   ` Jason Gunthorpe
2022-03-21 12:50     ` Jason Gunthorpe via iommu
2022-03-22  5:48     ` Lu Baolu
2022-03-22  5:48       ` Lu Baolu
2022-03-20  6:40 ` [PATCH RFC 11/11] iommu: Rename iommu-sva-lib.{c,h} Lu Baolu
2022-03-20  6:40   ` Lu Baolu

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