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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Paul Durrant <Paul.Durrant@citrix.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: Julien Grall <julien.grall@arm.com>,
	Stefano Stabellini <sstabellini@kernel.org>,
	Jan Beulich <jbeulich@suse.com>,
	Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Subject: Re: [PATCH v5 02/15] iommu: introduce the concept of BFN...
Date: Tue, 7 Aug 2018 08:26:51 +0000	[thread overview]
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D1912AE938@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <b34ed3dd8dd941a99b00416943dde3a8@AMSPEX02CL03.citrite.net>

> From: Paul Durrant [mailto:Paul.Durrant@citrix.com]
> Sent: Tuesday, August 7, 2018 4:00 PM
> 
> > >   *
> > >   * gfn: Guest Frame Number
> > >   *   The values a guest puts in its own pagetables.  For an auto-
> translated
> > > @@ -26,6 +27,11 @@
> > >   *   A linear idea of a guest physical address space. For an auto-
> translated
> > >   *   guest, pfn == gfn while for a non-translated guest, pfn != gfn.
> > >   *
> > > + * bfn: Bus Frame Number (definitions in include/xen/iommu.h)
> > > + *   The linear frame numbers of IOMMU address space. All initiators
> for a
> > > + *   given domain share a single IOMMU address space and, by default,
> > > Xen will
> > > + *   ensure bfn == pfn.
> > > + *
> >
> > Above description is a bit confusing:
> >
> > - for 'domain', are you talking about VM or IOMMU domain? If the
> former
> > then each initiator could have its own IOMMU address space when a
> virtual
> > IOMMU (either pvIOMMU or emulated IOMMU) is exposed.
> >
> 
> I mean VM and, yes, while each initiator *could* have its own IOMMU
> address space, that is not what we do in (or have ever done) in Xen. I can
> replace the word 'domain' with the abbreviation 'VM' if you feel it makes
> things clearer.
> 

domain is OK here. just want to confirm.

> > - since you talk about 'by default', better also talk about non-default case,
> > i.e. when virtual IOMMU is exposed then bfn is a separate address space
> > managed by guest
> 
> That's putting the cart before the horse really. There is no PV-IOMMU at
> this stage in the series. I guess I could modify the comment in the later
> patch where I add the hypercall to enable PV-IOMMU.
> 

it's fine as long as finally the information is complete. 

Thanks
Kevin


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  reply	other threads:[~2018-08-07  8:26 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-03 17:22 [PATCH v5 00/15] paravirtual IOMMU interface Paul Durrant
2018-08-03 17:22 ` [PATCH v5 01/15] iommu: turn need_iommu back into a boolean Paul Durrant
2018-08-08 13:39   ` Jan Beulich
2018-08-08 13:56     ` Paul Durrant
2018-08-03 17:22 ` [PATCH v5 02/15] iommu: introduce the concept of BFN Paul Durrant
2018-08-07  2:38   ` Tian, Kevin
2018-08-07  7:59     ` Paul Durrant
2018-08-07  8:26       ` Tian, Kevin [this message]
2018-08-03 17:22 ` [PATCH v5 03/15] iommu: make use of type-safe BFN and MFN in exported functions Paul Durrant
2018-08-07  2:45   ` Tian, Kevin
2018-08-03 17:22 ` [PATCH v5 04/15] iommu: push use of type-safe BFN and MFN into iommu_ops Paul Durrant
2018-08-07  2:49   ` Tian, Kevin
2018-08-03 17:22 ` [PATCH v5 05/15] iommu: don't domain_crash() inside iommu_map/unmap_page() Paul Durrant
2018-08-07  2:55   ` Tian, Kevin
2018-08-07  8:05     ` Paul Durrant
2018-08-07  8:23       ` Jan Beulich
2018-08-03 17:22 ` [PATCH v5 06/15] public / x86: introduce __HYPERCALL_iommu_op Paul Durrant
2018-08-07  3:00   ` Tian, Kevin
2018-08-07  8:10     ` Paul Durrant
2018-08-07  8:25       ` Jan Beulich
2018-08-17 21:10   ` Daniel De Graaf
2018-08-03 17:22 ` [PATCH v5 07/15] iommu: track reserved ranges using a rangeset Paul Durrant
2018-08-07  3:04   ` Tian, Kevin
2018-08-07  8:16     ` Paul Durrant
2018-08-07  8:23       ` Tian, Kevin
2018-08-03 17:22 ` [PATCH v5 08/15] x86: add iommu_op to query reserved ranges Paul Durrant
2018-08-03 17:22 ` [PATCH v5 09/15] vtd: add lookup_page method to iommu_ops Paul Durrant
2018-08-07  3:25   ` Tian, Kevin
2018-08-07  8:21     ` Paul Durrant
2018-08-07  8:29       ` Jan Beulich
2018-08-07  8:32         ` Tian, Kevin
2018-08-07  8:37           ` Paul Durrant
2018-08-07  8:48             ` Tian, Kevin
2018-08-07  8:56               ` Paul Durrant
2018-08-07  9:03                 ` Tian, Kevin
2018-08-07  9:07                   ` Paul Durrant
2018-08-07  8:31       ` Tian, Kevin
2018-08-07  8:35         ` Paul Durrant
2018-08-07  8:47           ` Tian, Kevin
2018-08-03 17:22 ` [PATCH v5 10/15] mm / iommu: include need_iommu() test in iommu_use_hap_pt() Paul Durrant
2018-08-07  3:32   ` Tian, Kevin
2018-08-03 17:22 ` [PATCH v5 11/15] mm / iommu: split need_iommu() into has_iommu_pt() and sync_iommu_pt() Paul Durrant
2018-08-03 18:18   ` Razvan Cojocaru
2018-08-07  3:41   ` Tian, Kevin
2018-08-07  8:24     ` Paul Durrant
2018-08-03 17:22 ` [PATCH v5 12/15] x86: add iommu_op to enable modification of IOMMU mappings Paul Durrant
2018-08-07  4:08   ` Tian, Kevin
2018-08-07  8:32     ` Paul Durrant
2018-08-07  8:37       ` Tian, Kevin
2018-08-07  8:44         ` Paul Durrant
2018-08-07  9:01           ` Tian, Kevin
2018-08-07  9:12             ` Paul Durrant
2018-08-07  9:19               ` Tian, Kevin
2018-08-07  9:22                 ` Paul Durrant
2018-08-03 17:22 ` [PATCH v5 13/15] memory: add get_paged_gfn() as a wrapper Paul Durrant
2018-08-03 17:22 ` [PATCH v5 14/15] x86: add iommu_ops to modify and flush IOMMU mappings Paul Durrant
2018-08-03 17:22 ` [PATCH v5 15/15] x86: extend the map and unmap iommu_ops to support grant references Paul Durrant

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