From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>
Cc: Ashok Raj <ashok.raj@intel.com>,
Will Deacon <will.deacon@arm.com>,
iommu@lists.linux-foundation.org,
Robin Murphy <robin.murphy@arm.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH V2 3/5] iommu: Add support to change default domain of an iommu_group
Date: Wed, 4 Mar 2020 20:17:04 +0800 [thread overview]
Message-ID: <64f24e39-2abb-992d-d7ca-8e47c927aff3@linux.intel.com> (raw)
In-Reply-To: <20200303131326.GB13185@8bytes.org>
Hi Joerg,
On 2020/3/3 21:13, Joerg Roedel wrote:
> Hi Baolu,
>
> On Tue, Mar 03, 2020 at 02:47:02PM +0800, Lu Baolu wrote:
>> Theoretically speaking, per-device default domain is impractical. PCI
>> aliased devices (PCI bridge and all devices beneath it, VMD devices and
>> various devices quirked with pci_add_dma_alias()) must use the same
>> domain. It's likely that we have to introduce something like a sub-group
>> with all PCI aliased devices staying in it. Current private-domain
>> implementation in the vt-d driver was introduced for compatible purpose
>> and I wanted to abandon it from the first day. :-)
>
> What hinders you from removing it now? I looked a bit closer into
> these private default domain implementation and it is very fragile. If
> it can be removed, then better do so sooner than later.
>
I will soon send out the patches for review.
>> Probably, we are able to configure per-group default domain type with
>> below two interfaces.
>>
>> - (ops->)dev_def_domain_type: Return the required default domain type
>> for a device. It returns
>> - IOMMU_DOMAIN_DMA (device must use a DMA domain), unlikely
>> - IOMMU_DOMAIN_IDENTITY (device must use an Identity domain), unlikely
>> - 0 (both are okay), likely
>
> If we stay at the group level, this interface should work on the group
> level too, and not on the device level.
>
>> - iommu_group_change_def_domain: Change the default domain of a group
>> Works only when all devices have no driver bond.
>
> Btw, I have no objections about the concept of private default domains
> for devices, but the implementation should be moved to generic IOMMU
> code so that the behavior is consistent accross differnet IOMMU
> platforms, and of course be robust.
>
Yes. I agree with you.
>
> Regards,
>
> Joerg
>
Best regards,
baolu
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next prev parent reply other threads:[~2020-03-04 12:17 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 [this message]
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
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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