From: "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@intel.com>
To: Lu Baolu <baolu.lu@linux.intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>
Cc: "Raj, Ashok" <ashok.raj@intel.com>,
Will Deacon <will.deacon@arm.com>,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>
Subject: RE: [PATCH V2 5/5] iommu: Document usage of "/sys/kernel/iommu_groups/<grp_id>/type" file
Date: Mon, 24 Feb 2020 02:18:16 +0000 [thread overview]
Message-ID: <FFF73D592F13FD46B8700F0A279B802F57216C77@ORSMSX114.amr.corp.intel.com> (raw)
In-Reply-To: <f8b07b5e-9a11-1dbe-9fb6-47b851a1b661@linux.intel.com>
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> > +What: /sys/kernel/iommu_groups/<grp_id>/type
> > +Date: February 2020
> > +KernelVersion: v5.6
> > +Contact: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com<mailto:sai.praneeth.prakhya@intel.com>>
> > +Description: Lets the user know the type of default domain in use by iommu
> > + for this group. A privileged user could request kernel to change
>
> Let the users know the default domain type of the IOMMU group by reading this
> file. A privileged user could request to change it by writing to this file.
Sure! Will fix it.
> > + the group type by writing to this file. Presently, only three
> > + types are supported
> > + 1. DMA: All the DMA transactions from the devices in this group
> > + are translated by the iommu.
> > + 2. identity: All the DMA transactions from the devices in this
> > + group are *not* translated by the iommu.
> > + 3. auto: Kernel decides one among DMA/identity mode and
> hence
> > + when the user reads the file he would never see "auto".
>
> Just out of curiosity, when could a user reads "auto" from this file?
Never, because when a user requests kernel to change to "auto" mode, kernel will select one among identity or DMA. So, default domain type cannot be auto, it's always either identity or DMA.
"auto" mode is just a write value where user is requesting kernel to select one among identity or DMA.
> > + This is just a write only value.
> > + Note:
> > + -----
> > + A group type could be modified only when *all* the devices in
>
> group's default domain type (not group type).
Sure! Makes sense.. will fix it 😊
>
> > + the group are not binded to any device driver. So, the user has
>
> bound
Makes sense.. will fix this too.
Regards,
Sai
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next prev parent reply other threads:[~2020-02-24 2:18 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-16 21:57 [PATCH V2 0/5] iommu: Add support to change default domain of a group Sai Praneeth Prakhya
2020-02-16 21:57 ` [PATCH V2 1/5] iommu: Add dev_def_domain_type() call back function to iommu_ops Sai Praneeth Prakhya
2020-02-22 23:37 ` Lu Baolu
2020-02-22 23:39 ` Prakhya, Sai Praneeth
2020-02-16 21:57 ` [PATCH V2 2/5] iommu/vt-d: Rename device_def_domain_type() to intel_iommu_dev_def_domain_type() Sai Praneeth Prakhya
2020-02-22 23:42 ` Lu Baolu
2020-02-22 23:59 ` Prakhya, Sai Praneeth
2020-02-23 1:50 ` Lu Baolu
2020-02-24 3:23 ` Prakhya, Sai Praneeth
2020-02-16 21:57 ` [PATCH V2 3/5] iommu: Add support to change default domain of an iommu_group Sai Praneeth Prakhya
2020-02-23 1:20 ` Lu Baolu
2020-02-24 3:20 ` Prakhya, Sai Praneeth
2020-02-24 5:46 ` Lu Baolu
2020-02-24 7:03 ` Prakhya, Sai Praneeth
2020-02-24 7:39 ` Lu Baolu
2020-02-24 7:57 ` Prakhya, Sai Praneeth
2020-02-24 8:12 ` Lu Baolu
2020-02-24 8:39 ` Lu Baolu
2020-02-24 8:44 ` Prakhya, Sai Praneeth
2020-03-02 15:08 ` Joerg Roedel
2020-03-03 6:47 ` Lu Baolu
2020-03-03 13:13 ` Joerg Roedel
2020-03-04 12:17 ` Lu Baolu
2020-02-16 21:57 ` [PATCH V2 4/5] iommu: Take lock before reading iommu_group default domain type Sai Praneeth Prakhya
2020-02-16 21:57 ` [PATCH V2 5/5] iommu: Document usage of "/sys/kernel/iommu_groups/<grp_id>/type" file Sai Praneeth Prakhya
2020-02-23 1:38 ` Lu Baolu
2020-02-24 2:18 ` Prakhya, Sai Praneeth [this message]
2020-02-22 23:40 ` [PATCH V2 0/5] iommu: Add support to change default domain of a group Prakhya, Sai Praneeth
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