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From: Zach Pfeffer <zpfeffer@codeaurora.org>
To: Joerg Roedel <joro@8bytes.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	Daniel Walker <dwalker@codeaurora.org>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	mel@csn.ul.ie, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-omap@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager
Date: Mon, 12 Jul 2010 22:52:43 -0700	[thread overview]
Message-ID: <4C3BFF2B.40006@codeaurora.org> (raw)
In-Reply-To: <20100710151111.GD10080@8bytes.org>

Joerg Roedel wrote:
> On Thu, Jul 01, 2010 at 11:17:34PM -0700, Zach Pfeffer wrote:
>> Andi Kleen wrote:
> 
>>> Hmm? dma_map_* does not change any CPU mappings. It only sets up
>>> DMA mapping(s).
>> Sure, but I was saying that iommu_map() doesn't just set up the IOMMU
>> mappings, its sets up both the iommu and kernel buffer mappings.
> 
> What do you mean by kernel buffer mappings?

In-kernel mappings whose addresses can be dereferenced. 

> 
> 
>>> That assumes that all the IOMMUs on the system support the same page table
>>> format, right?
>> Actually no. Since the VCMM abstracts a page-table as a Virtual
>> Contiguous Region (VCM) a VCM can be associated with any device,
>> regardless of their individual page table format.
> 
> The IOMMU-API abstracts a page-table as a domain which can also be
> associated with any device (behind an iommu).

It does, but only by convention. The domain member is just a big
catchall void *. It would be more useful to factor out a VCM
abstraction, with associated ops. As it stands all IOMMU device driver
writters have to re-invent IOMMU virtual address management.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

WARNING: multiple messages have this Message-ID (diff)
From: Zach Pfeffer <zpfeffer@codeaurora.org>
To: Joerg Roedel <joro@8bytes.org>
Cc: Andi Kleen <andi@firstfloor.org>,
	Daniel Walker <dwalker@codeaurora.org>,
	Randy Dunlap <randy.dunlap@oracle.com>,
	mel@csn.ul.ie, linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org, linux-omap@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager
Date: Mon, 12 Jul 2010 22:52:43 -0700	[thread overview]
Message-ID: <4C3BFF2B.40006@codeaurora.org> (raw)
In-Reply-To: <20100710151111.GD10080@8bytes.org>

Joerg Roedel wrote:
> On Thu, Jul 01, 2010 at 11:17:34PM -0700, Zach Pfeffer wrote:
>> Andi Kleen wrote:
> 
>>> Hmm? dma_map_* does not change any CPU mappings. It only sets up
>>> DMA mapping(s).
>> Sure, but I was saying that iommu_map() doesn't just set up the IOMMU
>> mappings, its sets up both the iommu and kernel buffer mappings.
> 
> What do you mean by kernel buffer mappings?

In-kernel mappings whose addresses can be dereferenced. 

> 
> 
>>> That assumes that all the IOMMUs on the system support the same page table
>>> format, right?
>> Actually no. Since the VCMM abstracts a page-table as a Virtual
>> Contiguous Region (VCM) a VCM can be associated with any device,
>> regardless of their individual page table format.
> 
> The IOMMU-API abstracts a page-table as a domain which can also be
> associated with any device (behind an iommu).

It does, but only by convention. The domain member is just a big
catchall void *. It would be more useful to factor out a VCM
abstraction, with associated ops. As it stands all IOMMU device driver
writters have to re-invent IOMMU virtual address management.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

--
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WARNING: multiple messages have this Message-ID (diff)
From: zpfeffer@codeaurora.org (Zach Pfeffer)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager
Date: Mon, 12 Jul 2010 22:52:43 -0700	[thread overview]
Message-ID: <4C3BFF2B.40006@codeaurora.org> (raw)
In-Reply-To: <20100710151111.GD10080@8bytes.org>

Joerg Roedel wrote:
> On Thu, Jul 01, 2010 at 11:17:34PM -0700, Zach Pfeffer wrote:
>> Andi Kleen wrote:
> 
>>> Hmm? dma_map_* does not change any CPU mappings. It only sets up
>>> DMA mapping(s).
>> Sure, but I was saying that iommu_map() doesn't just set up the IOMMU
>> mappings, its sets up both the iommu and kernel buffer mappings.
> 
> What do you mean by kernel buffer mappings?

In-kernel mappings whose addresses can be dereferenced. 

> 
> 
>>> That assumes that all the IOMMUs on the system support the same page table
>>> format, right?
>> Actually no. Since the VCMM abstracts a page-table as a Virtual
>> Contiguous Region (VCM) a VCM can be associated with any device,
>> regardless of their individual page table format.
> 
> The IOMMU-API abstracts a page-table as a domain which can also be
> associated with any device (behind an iommu).

It does, but only by convention. The domain member is just a big
catchall void *. It would be more useful to factor out a VCM
abstraction, with associated ops. As it stands all IOMMU device driver
writters have to re-invent IOMMU virtual address management.

-- 
Sent by an employee of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.

  reply	other threads:[~2010-07-13  5:52 UTC|newest]

Thread overview: 142+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-06-30  5:55 [RFC 1/3] mm: iommu: An API to unify IOMMU, CPU and device memory management Zach Pfeffer
2010-06-30  5:55 ` Zach Pfeffer
2010-06-30  5:55 ` Zach Pfeffer
2010-06-30  5:55 ` [RFC 2/3] mm: iommu: A physical allocator for the VCMM Zach Pfeffer
2010-06-30  5:55   ` Zach Pfeffer
2010-06-30  5:55   ` Zach Pfeffer
2010-06-30  5:55 ` [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager Zach Pfeffer
2010-06-30  5:55   ` Zach Pfeffer
2010-06-30  5:55   ` Zach Pfeffer
2010-07-01 17:17   ` Randy Dunlap
2010-07-01 17:17     ` Randy Dunlap
2010-07-01 17:17     ` Randy Dunlap
2010-07-01 18:02     ` Andi Kleen
2010-07-01 18:02       ` Andi Kleen
2010-07-01 18:02       ` Andi Kleen
2010-07-01 19:28       ` Daniel Walker
2010-07-01 19:28         ` Daniel Walker
2010-07-01 19:28         ` Daniel Walker
2010-07-01 19:38         ` Andi Kleen
2010-07-01 19:38           ` Andi Kleen
2010-07-01 19:38           ` Andi Kleen
2010-07-01 19:42           ` Daniel Walker
2010-07-01 19:42             ` Daniel Walker
2010-07-01 19:42             ` Daniel Walker
2010-07-01 22:15             ` Hari Kanigeri
2010-07-01 22:15               ` Hari Kanigeri
2010-07-01 22:15               ` Hari Kanigeri
2010-07-02  7:09               ` Zach Pfeffer
2010-07-02  7:09                 ` Zach Pfeffer
2010-07-02  7:09                 ` Zach Pfeffer
2010-07-10 14:36                 ` Joerg Roedel
2010-07-10 14:36                   ` Joerg Roedel
2010-07-10 14:36                   ` Joerg Roedel
2010-07-13  5:21                   ` Zach Pfeffer
2010-07-13  5:21                     ` Zach Pfeffer
2010-07-13  5:21                     ` Zach Pfeffer
2010-07-14 19:34                     ` Joerg Roedel
2010-07-14 19:34                       ` Joerg Roedel
2010-07-14 19:34                       ` Joerg Roedel
2010-07-15  1:18                       ` Zach Pfeffer
2010-07-15  1:18                         ` Zach Pfeffer
2010-07-15  1:18                         ` Zach Pfeffer
2010-07-01 22:00           ` Zach Pfeffer
2010-07-01 22:00             ` Zach Pfeffer
2010-07-01 22:00             ` Zach Pfeffer
2010-07-01 22:05             ` Daniel Walker
2010-07-01 22:05               ` Daniel Walker
2010-07-01 22:05               ` Daniel Walker
2010-07-02  7:33               ` Zach Pfeffer
2010-07-02  7:33                 ` Zach Pfeffer
2010-07-02  7:33                 ` Zach Pfeffer
2010-07-10 14:56                 ` Joerg Roedel
2010-07-10 14:56                   ` Joerg Roedel
2010-07-10 14:56                   ` Joerg Roedel
2010-07-13  5:46                   ` Zach Pfeffer
2010-07-13  5:46                     ` Zach Pfeffer
2010-07-13  5:46                     ` Zach Pfeffer
2010-07-13  5:59                     ` FUJITA Tomonori
2010-07-13  5:59                       ` FUJITA Tomonori
2010-07-13  5:59                       ` FUJITA Tomonori
2010-07-13  8:20                       ` Alan Cox
2010-07-13  8:20                         ` Alan Cox
2010-07-13  8:20                         ` Alan Cox
2010-07-13  8:30                         ` FUJITA Tomonori
2010-07-13  8:30                           ` FUJITA Tomonori
2010-07-13  8:30                           ` FUJITA Tomonori
2010-07-13  8:42                           ` Alan Cox
2010-07-13  8:42                             ` Alan Cox
2010-07-13  8:42                             ` Alan Cox
2010-07-13  8:45                             ` FUJITA Tomonori
2010-07-13  8:45                               ` FUJITA Tomonori
2010-07-13  8:45                               ` FUJITA Tomonori
2010-07-13  9:02                               ` Russell King - ARM Linux
2010-07-13  9:02                                 ` Russell King - ARM Linux
2010-07-13  9:02                                 ` Russell King - ARM Linux
2010-07-14  1:59                                 ` FUJITA Tomonori
2010-07-14  1:59                                   ` FUJITA Tomonori
2010-07-14  1:59                                   ` FUJITA Tomonori
2010-07-22  3:50                                   ` Zach Pfeffer
2010-07-22  3:50                                     ` Zach Pfeffer
2010-07-22  3:50                                     ` Zach Pfeffer
2010-07-22  4:47                                     ` FUJITA Tomonori
2010-07-22  4:47                                       ` FUJITA Tomonori
2010-07-22  4:47                                       ` FUJITA Tomonori
2010-07-22 16:33                                       ` Zach Pfeffer
2010-07-22 16:33                                         ` Zach Pfeffer
2010-07-22 16:33                                         ` Zach Pfeffer
2010-07-22  7:51                                     ` Russell King - ARM Linux
2010-07-22  7:51                                       ` Russell King - ARM Linux
2010-07-22  7:51                                       ` Russell King - ARM Linux
2010-07-22 16:13                                       ` Zach Pfeffer
2010-07-22 16:13                                         ` Zach Pfeffer
2010-07-22 16:13                                         ` Zach Pfeffer
2010-07-13 12:06                       ` Zach Pfeffer
2010-07-13 12:06                         ` Zach Pfeffer
2010-07-13 12:06                         ` Zach Pfeffer
2010-07-01 22:51             ` Hari Kanigeri
2010-07-01 22:51               ` Hari Kanigeri
2010-07-01 22:51               ` Hari Kanigeri
2010-07-02  7:29               ` Zach Pfeffer
2010-07-02  7:29                 ` Zach Pfeffer
2010-07-01 23:00             ` Andi Kleen
2010-07-01 23:00               ` Andi Kleen
2010-07-01 23:00               ` Andi Kleen
2010-07-02  6:17               ` Zach Pfeffer
2010-07-02  6:17                 ` Zach Pfeffer
2010-07-02  6:17                 ` Zach Pfeffer
2010-07-02  8:22                 ` Andi Kleen
2010-07-02  8:22                   ` Andi Kleen
2010-07-02  8:22                   ` Andi Kleen
2010-07-02 18:42                   ` Zach Pfeffer
2010-07-02 18:42                     ` Zach Pfeffer
2010-07-02 18:42                     ` Zach Pfeffer
2010-07-10 15:11                 ` Joerg Roedel
2010-07-10 15:11                   ` Joerg Roedel
2010-07-10 15:11                   ` Joerg Roedel
2010-07-13  5:52                   ` Zach Pfeffer [this message]
2010-07-13  5:52                     ` Zach Pfeffer
2010-07-13  5:52                     ` Zach Pfeffer
2010-07-03  6:36               ` Zach Pfeffer
2010-07-03  6:36                 ` Zach Pfeffer
2010-07-10 14:54             ` Joerg Roedel
2010-07-10 14:54               ` Joerg Roedel
2010-07-10 14:54               ` Joerg Roedel
2010-07-13  5:27               ` Zach Pfeffer
2010-07-13  5:27                 ` Zach Pfeffer
2010-07-13  5:27                 ` Zach Pfeffer
2010-07-01 20:59     ` Paul Walmsley
2010-07-01 20:59       ` Paul Walmsley
2010-07-01 20:59       ` Paul Walmsley
2010-07-01 21:48       ` Randy Dunlap
2010-07-01 21:48         ` Randy Dunlap
2010-07-01 21:48         ` Randy Dunlap
2010-06-30 23:40 ` [RFC 1/3] mm: iommu: An API to unify IOMMU, CPU and device memory management Randy Dunlap
2010-06-30 23:40   ` Randy Dunlap
2010-06-30 23:40   ` Randy Dunlap
2010-07-01  7:16   ` Zach Pfeffer
2010-07-01  7:16     ` Zach Pfeffer
2010-07-01  7:16     ` Zach Pfeffer
2010-07-02  7:00     ` Paul Mundt
2010-07-02  7:00       ` Paul Mundt
2010-07-02  7:00       ` Paul Mundt

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