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From: Wei Liu <wei.liu2@citrix.com>
To: Paul Durrant <Paul.Durrant@citrix.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>,
	Wei Liu <wei.liu2@citrix.com>,
	Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"Tim (Xen.org)" <tim@xen.org>,
	George Dunlap <George.Dunlap@citrix.com>,
	Julien Grall <julien.grall@arm.com>,
	Jan Beulich <jbeulich@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
	Ian Jackson <Ian.Jackson@citrix.com>
Subject: Re: [PATCH v3 10/13] x86: add iommu_op to enable modification of IOMMU mappings
Date: Fri, 20 Jul 2018 10:30:21 +0100	[thread overview]
Message-ID: <20180720093021.wjwh3vc6qmpqiuom@citrix.com> (raw)
In-Reply-To: <9693246090d5443b9a5ce8e0d7d7277f@AMSPEX02CL03.citrite.net>

On Fri, Jul 20, 2018 at 10:19:44AM +0100, Paul Durrant wrote:
> > >
> > > I think this flag currently serves two purposes: one is to indicate
> > > whether there are resources allocated within xen, the other it indicate
> > > whether it is in use (as suggested in the comment).
> > >
> > > Suppose a domain gets all its devices deassigned after this call,
> > > original iommu_teardown would have been called, but now it won't. The
> > > iommu will still be torn down when it is destroyed, but this is a very
> > > subtle change in behaviour.
> > 
> > That is pretty subtle.
> 
> Actually, thinking a bit more, that is the semantic I want. The domain
> is taking control of its own mappings. It doesn't want Xen to tear
> them down under its feet.

Oh, this makes sense.

> 
> > 
> > >
> > > IMHO we should clearly separate these two cases if possible.
> > >
> > 
> > Agreed. I never liked the 'need_iommu' name anyway. I'll add a patch before
> > this one to do the rename/split.
> > 
> 
> I still think this renaming/clarification is worthwhile so I'll still
> add something into the series.
> 

Thanks.

Wei.

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  reply	other threads:[~2018-07-20  9:30 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-17 13:38 [PATCH v3 00/13] paravirtual IOMMU interface Paul Durrant
2018-07-17 13:38 ` [PATCH v3 01/13] grant_table: use term 'mfn' for machine frame numbers Paul Durrant
2018-07-17 13:38 ` [PATCH v3 02/13] iommu: introduce the concept of BFN Paul Durrant
2018-07-19  8:08   ` Wei Liu
2018-07-17 13:38 ` [PATCH v3 03/13] iommu: make use of type-safe BFN and MFN in exported functions Paul Durrant
2018-07-19  8:08   ` Wei Liu
2018-07-17 13:38 ` [PATCH v3 04/13] iommu: push use of type-safe BFN and MFN into iommu_ops Paul Durrant
2018-07-19  8:10   ` Wei Liu
2018-07-17 13:38 ` [PATCH v3 05/13] iommu: don't domain_crash() inside iommu_map/unmap_page() Paul Durrant
2018-07-17 13:38 ` [PATCH v3 06/13] public / x86: introduce __HYPERCALL_iommu_op Paul Durrant
2018-07-17 13:38 ` [PATCH v3 07/13] iommu: track reserved ranges using a rangeset Paul Durrant
2018-07-19  9:01   ` Wei Liu
2018-07-17 13:38 ` [PATCH v3 08/13] x86: add iommu_op to query reserved ranges Paul Durrant
2018-07-19  9:37   ` Wei Liu
2018-07-19 10:03     ` Paul Durrant
2018-07-17 13:38 ` [PATCH v3 09/13] vtd: add lookup_page method to iommu_ops Paul Durrant
2018-07-19  9:55   ` Wei Liu
2018-07-17 13:38 ` [PATCH v3 10/13] x86: add iommu_op to enable modification of IOMMU mappings Paul Durrant
2018-07-20  8:59   ` Wei Liu
2018-07-20  9:05     ` Paul Durrant
2018-07-20  9:19       ` Paul Durrant
2018-07-20  9:30         ` Wei Liu [this message]
2018-07-17 13:38 ` [PATCH v3 11/13] memory: add get_paged_gfn() as a wrapper Paul Durrant
2018-07-17 13:38 ` [PATCH v3 12/13] x86: add iommu_ops to modify and flush IOMMU mappings Paul Durrant
2018-07-23 13:35   ` Wei Liu
2018-07-23 13:40     ` Paul Durrant
2018-07-23 13:49       ` Wei Liu
2018-07-23 14:26   ` Wei Liu
2018-07-23 14:27     ` Paul Durrant
2018-07-17 13:38 ` [PATCH v3 13/13] x86: extend the map and unmap iommu_ops to support grant references Paul Durrant

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