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From: Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
To: Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>
Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
	laurent.pinchart-ryLnwIuWjnjg/C1BVhZhaw@public.gmane.org,
	Varun.Sethi-KZfg59tc24xl57MIdRCFDg@public.gmane.org,
	dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org,
	linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org
Subject: Re: [GIT PULL] iommu: Kill off pgsize_bitmap field from struct iommu_ops
Date: Tue, 31 Mar 2015 16:24:40 +0200	[thread overview]
Message-ID: <20150331142440.GD22683@8bytes.org> (raw)
In-Reply-To: <20150327171946.GL1562-5wv7dgnIgG8@public.gmane.org>

Hi Will,

On Fri, Mar 27, 2015 at 05:19:46PM +0000, Will Deacon wrote:
> Please can you pull the following IOMMU changes for 4.1? They move the
> per-iommu_ops pgsize_bitmap field into the iommu_domain, which allows
> IOMMUs such as the ARM SMMU to support different page sizes within a
> given SoC.

I have some concerns about the direction taken with this patch-set. The
goal for the IOMMU-API is still to have domains that can be attached to
arbitrary devices (even when mappings already exist). But with this
patch-set we move into a direction where a domain can only be used on
IOMMUs that support the page-sizes required by the domain. In the end
this would be visible to the user of the IOMMU-API, which is not what we
want.

I can understand the motivation behind these patches, but we need to
think about how this could work with the desired semantics of the
IOMMU-API.


	Joerg

WARNING: multiple messages have this Message-ID (diff)
From: joro@8bytes.org (Joerg Roedel)
To: linux-arm-kernel@lists.infradead.org
Subject: [GIT PULL] iommu: Kill off pgsize_bitmap field from struct iommu_ops
Date: Tue, 31 Mar 2015 16:24:40 +0200	[thread overview]
Message-ID: <20150331142440.GD22683@8bytes.org> (raw)
In-Reply-To: <20150327171946.GL1562@arm.com>

Hi Will,

On Fri, Mar 27, 2015 at 05:19:46PM +0000, Will Deacon wrote:
> Please can you pull the following IOMMU changes for 4.1? They move the
> per-iommu_ops pgsize_bitmap field into the iommu_domain, which allows
> IOMMUs such as the ARM SMMU to support different page sizes within a
> given SoC.

I have some concerns about the direction taken with this patch-set. The
goal for the IOMMU-API is still to have domains that can be attached to
arbitrary devices (even when mappings already exist). But with this
patch-set we move into a direction where a domain can only be used on
IOMMUs that support the page-sizes required by the domain. In the end
this would be visible to the user of the IOMMU-API, which is not what we
want.

I can understand the motivation behind these patches, but we need to
think about how this could work with the desired semantics of the
IOMMU-API.


	Joerg

  parent reply	other threads:[~2015-03-31 14:24 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-27 17:19 [GIT PULL] iommu: Kill off pgsize_bitmap field from struct iommu_ops Will Deacon
2015-03-27 17:19 ` Will Deacon
     [not found] ` <20150327171946.GL1562-5wv7dgnIgG8@public.gmane.org>
2015-03-31 14:24   ` Joerg Roedel [this message]
2015-03-31 14:24     ` Joerg Roedel
     [not found]     ` <20150331142440.GD22683-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-03-31 14:49       ` Will Deacon
2015-03-31 14:49         ` Will Deacon
     [not found]         ` <20150331144956.GA24094-5wv7dgnIgG8@public.gmane.org>
2015-03-31 15:50           ` Alex Williamson
2015-03-31 15:50             ` Alex Williamson
     [not found]             ` <1427817050.5567.148.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-04-01 11:53               ` Will Deacon
2015-04-01 11:53                 ` Will Deacon
     [not found]                 ` <20150401115340.GG1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 15:53                   ` Joerg Roedel
2015-04-01 15:53                     ` Joerg Roedel
2015-04-01 16:45                   ` Alex Williamson
2015-04-01 16:45                     ` Alex Williamson
2015-04-01 15:38           ` Joerg Roedel
2015-04-01 15:38             ` Joerg Roedel
     [not found]             ` <20150401153854.GG4441-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-04-01 17:03               ` Will Deacon
2015-04-01 17:03                 ` Will Deacon
     [not found]                 ` <20150401170330.GO1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 21:24                   ` Joerg Roedel
2015-04-01 21:24                     ` Joerg Roedel
2015-03-31 16:07       ` Robin Murphy
2015-03-31 16:07         ` Robin Murphy
2015-04-01 13:14   ` David Woodhouse
2015-04-01 13:14     ` David Woodhouse
     [not found]     ` <1427894051.22236.6.camel-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-04-01 13:39       ` Will Deacon
2015-04-01 13:39         ` Will Deacon
     [not found]         ` <20150401133908.GI1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 13:52           ` David Woodhouse
2015-04-01 13:52             ` David Woodhouse
     [not found]             ` <1427896377.22236.8.camel-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-04-01 14:05               ` Will Deacon
2015-04-01 14:05                 ` Will Deacon
     [not found]                 ` <20150401140512.GJ1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 14:28                   ` David Woodhouse
2015-04-01 14:28                     ` David Woodhouse
     [not found]                     ` <1427898490.22236.10.camel-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-04-01 14:39                       ` Will Deacon
2015-04-01 14:39                         ` Will Deacon
     [not found]                         ` <20150401143904.GL1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 14:46                           ` David Woodhouse
2015-04-01 14:46                             ` David Woodhouse
     [not found]                             ` <1427899570.22236.14.camel-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-04-01 16:36                               ` Will Deacon
2015-04-01 16:36                                 ` Will Deacon
     [not found]                                 ` <20150401163618.GN1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 21:28                                   ` joro-zLv9SwRftAIdnm+yROfE0A
2015-04-01 21:28                                     ` joro at 8bytes.org
     [not found]                                     ` <20150401212854.GK4441-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
2015-04-02  8:58                                       ` Will Deacon
2015-04-02  8:58                                         ` Will Deacon
2015-04-01 16:51               ` Alex Williamson
2015-04-01 16:51                 ` Alex Williamson
     [not found]                 ` <1427907064.5567.256.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
2015-04-01 17:50                   ` Will Deacon
2015-04-01 17:50                     ` Will Deacon
     [not found]                     ` <20150401175040.GQ1552-5wv7dgnIgG8@public.gmane.org>
2015-04-01 18:18                       ` Alex Williamson
2015-04-01 18:18                         ` Alex Williamson

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