From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
To: Lu Baolu <baolu.lu@linux.intel.com>,
Joerg Roedel <joro@8bytes.org>,
David Woodhouse <dwmw2@infradead.org>,
Alex Williamson <alex.williamson@redhat.com>,
Kirti Wankhede <kwankhede@nvidia.com>
Cc: "kevin.tian@intel.com" <kevin.tian@intel.com>,
"ashok.raj@intel.com" <ashok.raj@intel.com>,
"tiwei.bie@intel.com" <tiwei.bie@intel.com>,
"sanjay.k.kumar@intel.com" <sanjay.k.kumar@intel.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"yi.y.sun@intel.com" <yi.y.sun@intel.com>,
"jacob.jun.pan@intel.com" <jacob.jun.pan@intel.com>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Subject: Re: [RFC PATCH v2 08/10] vfio/type1: Add domain at(de)taching group helpers
Date: Wed, 12 Sep 2018 18:54:26 +0100 [thread overview]
Message-ID: <04f5dc9d-71b1-37ec-402b-fae5f9e08664@arm.com> (raw)
In-Reply-To: <a97c8f75-ff49-5b87-198f-d3c8950d4e90@linux.intel.com>
On 12/09/2018 06:02, Lu Baolu wrote:
> Hi,
>
> On 09/11/2018 12:23 AM, Jean-Philippe Brucker wrote:
>> On 30/08/2018 05:09, Lu Baolu wrote:
>>> +static int vfio_detach_aux_domain(struct device *dev, void *data)
>>> +{
>>> + struct iommu_domain *domain = data;
>>> +
>>> + vfio_mdev_set_aux_domain(dev, NULL);
>>> + iommu_detach_device(domain, dev->parent);
>>
>> I think that's only going to work for vt-d, which doesn't use a
>> default_domain. For other drivers, iommu.c ends up calling
>> domain->ops->attach_dev(default_domain, dev) here, which isn't what we want.
>
> This doesn't break any functionality. It takes effect only if iommu
> hardware supports finer granular translation and advertises it through
> the API.>
>> That was my concern with reusing attach/detach_dev callbacks for PASID
>> management. The attach_dev code of IOMMU drivers already has to deal
>> with toggling between default and unmanaged domain. Dealing with more
>> state transitions in the same path is going to be difficult.
>
> Let's consider it from the API point of view.
>
> We have iommu_a(de)ttach_device() APIs to attach or detach a domain
> to/from a device. We should avoid applying a limitation of "these are
> only for single domain case, for multiple domains, use another API".
That's an idealized view of the API, the actual semantics aren't as
simple. For IOMMU drivers that implement IOMMU_DOMAIN_DMA in their
domain_alloc operation (Arm SMMU, AMD IOMMU, ...), attach_dev attaches
an unmanaged domain, detach_dev reattaches the default DMA domain, and
the detach_dev IOMMU op is not called. We can't change that now, so it's
difficult to add more functionality to attach_dev and detach_dev.
Thanks,
Jean
next prev parent reply other threads:[~2018-09-12 17:54 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-30 4:09 [RFC PATCH v2 00/10] vfio/mdev: IOMMU aware mediated device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 01/10] iommu: Add APIs for multiple domains per device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 02/10] iommu/vt-d: Add multiple domains per device query Lu Baolu
2018-09-05 19:35 ` Alex Williamson
2018-09-06 0:54 ` Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 03/10] iommu/amd: Add default branch in amd_iommu_capable() Lu Baolu
2018-09-05 19:37 ` Alex Williamson
2018-09-06 0:55 ` Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 04/10] iommu/vt-d: Enable/disable multiple domains per device Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 05/10] iommu/vt-d: Attach/detach domains in auxiliary mode Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 06/10] iommu/vt-d: Return ID associated with an auxiliary domain Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 07/10] vfio/mdev: Add mediated device domain type Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 08/10] vfio/type1: Add domain at(de)taching group helpers Lu Baolu
2018-09-10 16:23 ` Jean-Philippe Brucker
2018-09-12 5:02 ` Lu Baolu
2018-09-12 17:54 ` Jean-Philippe Brucker [this message]
2018-09-13 0:35 ` Tian, Kevin
2018-09-14 14:45 ` Jean-Philippe Brucker
2018-09-15 2:36 ` Tian, Kevin
2018-09-18 15:52 ` Jean-Philippe Brucker
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D19130EAD7@SHSMSX101.ccr.corp.intel.com>
2018-09-19 2:10 ` Lu Baolu
2018-09-25 17:55 ` Jean-Philippe Brucker
2018-09-26 2:11 ` Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 09/10] vfio/type1: Determine domain type of an mdev group Lu Baolu
2018-08-30 4:09 ` [RFC PATCH v2 10/10] vfio/type1: Attach domain for " Lu Baolu
2018-09-05 3:01 ` [RFC PATCH v2 00/10] vfio/mdev: IOMMU aware mediated device Tian, Kevin
2018-09-05 19:15 ` Alex Williamson
2018-09-06 1:29 ` Lu Baolu
2018-09-10 16:22 ` Jean-Philippe Brucker
2018-09-12 2:42 ` Lu Baolu
2018-09-12 17:54 ` Jean-Philippe Brucker
2018-09-13 0:19 ` Tian, Kevin
2018-09-13 15:03 ` Jean-Philippe Brucker
2018-09-13 16:55 ` Raj, Ashok
2018-09-14 14:39 ` Jean-Philippe Brucker
[not found] ` <AADFC41AFE54684AB9EE6CBC0274A5D191302ECE@SHSMSX101.ccr.corp.intel.com>
2018-09-14 14:40 ` Jean-Philippe Brucker
2018-09-14 21:04 ` Jacob Pan
2018-09-18 15:46 ` Jean-Philippe Brucker
2018-09-19 2:22 ` Tian, Kevin
2018-09-20 15:53 ` Jacob Pan
2018-09-14 2:46 ` Lu Baolu
2018-09-14 2:53 ` Tian, Kevin
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