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From: Joerg Roedel <joro@8bytes.org>
To: Will Deacon <will.deacon@arm.com>
Cc: "iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>, Kukjin Kim <kgene@kernel.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Heiko Stuebner <heiko@sntech.de>, Hiroshi Doyu <hdoyu@nvidia.com>,
	Stephen Warren <swarren@wwwdotorg.org>,
	Thierry Reding <thierry.reding@gmail.com>,
	Alexandre Courbot <gnurou@gmail.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"linux-samsung-soc@vger.kernel.org" 
	<linux-samsung-soc@vger.kernel.org>,
	"linux-rockchip@lists.infradead.org" 
	<linux-rockchip@lists.infradead.org>,
	"linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>,
	"jroedel@suse.de" <jroedel@suse.de>
Subject: Re: [PATCH 02/15] iommu: Introduce iommu domain types
Date: Fri, 30 Jan 2015 13:22:34 +0100	[thread overview]
Message-ID: <20150130122233.GA3702@8bytes.org> (raw)
In-Reply-To: <20150128141934.GP1569@arm.com>

Hi Will,

On Wed, Jan 28, 2015 at 02:19:34PM +0000, Will Deacon wrote:
> > +/* This are the possible domain-types */
> > +enum iommu_domain_type {
> > +	IOMMU_DOMAIN_DMA,	/* Domain used for DMA-API */
> > +	IOMMU_DOMAIN_IDENTITY,	/* Identity mapped domain  */
> 
> What happens if somebody calls map or unmap on an identity-mapping domain?
> Can we catch that in the IOMMU core before calling the IOMMU driver? That
> also implies we need something extra to parameterise the attributes for
> the mapping (e.g. cacheable, read-only) and also potentially the address
> range.

The domain type is only used by the IOMMU drivers to do be able to enter
special allocation paths (the AMD-Vi driver for example could allocate a
special internal domain type for IOMMU_DOMAIN_DMA).
But I think you are right, a couple of the current domain attributes we
have could be moved here, turning the domain-type into a bit-field. So
we could have bits for PAGING, CACHABLE, DMA_API and NESTING and build
the domain types above from those bits.

> > +	IOMMU_DOMAIN_UNMANAGED, /* Domain mappings are managed by a third party
> > +				   user (like KVM or VFIO) */
> 
> We already have the domain attributes (iommu_attr) to describe features
> of a domain. Is there really a need for this extra type, or can we extend
> the attribute set and allow for domain allocation with attributes?

I don't think that domains attributed will become obsolete with this
domain-type field. Some of the attributes should stay there for now,
like all the PAMU specific stuff. But I agree, some could be moved over.

	
	Joerg


  reply	other threads:[~2015-01-30 12:22 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-01-26 23:51 [PATCH 00/15] iommu: Move domain allocation into drivers Joerg Roedel
2015-01-26 23:51 ` [PATCH 01/15] iommu: Introduce domain_alloc and domain_free iommu_ops Joerg Roedel
2015-01-26 23:51 ` [PATCH 02/15] iommu: Introduce iommu domain types Joerg Roedel
2015-01-28 14:19   ` Will Deacon
2015-01-30 12:22     ` Joerg Roedel [this message]
2015-01-26 23:51 ` [PATCH 03/15] iommu/amd: Make use of domain_alloc and domain_free Joerg Roedel
2015-01-26 23:51 ` [PATCH 04/15] iommu/vt-d: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 05/15] iommu/omap: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 06/15] iommu/arm-smmu: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 07/15] iommu/exynos: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 08/15] iommu/tegra-smmu: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 09/15] iommu/tegra-gart: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 10/15] iommu/msm: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 11/15] iommu/shmobile: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 12/15] iommu/ipmmu-vmsa: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 13/15] iommu/rockchip: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 14/15] iommu/fsl: " Joerg Roedel
2015-01-26 23:51 ` [PATCH 15/15] iommu: Remove domain_init and domain_free iommu_ops Joerg Roedel
2015-03-20  9:24 ` [PATCH 00/15] iommu: Move domain allocation into drivers Yingjoe Chen
2015-03-23 11:49   ` Joerg Roedel
2015-03-23 13:35     ` Yingjoe Chen

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