linux-kernel - Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <4C3BFF2B.40006@codeaurora.org>
Date:	Mon, 12 Jul 2010 22:52:43 -0700
From:	Zach Pfeffer <zpfeffer@...eaurora.org>
To:	Joerg Roedel <joro@...tes.org>
CC:	Andi Kleen <andi@...stfloor.org>,
	Daniel Walker <dwalker@...eaurora.org>,
	Randy Dunlap <randy.dunlap@...cle.com>, mel@....ul.ie,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC 3/3] mm: iommu: The Virtual Contiguous Memory Manager

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.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/