linux-kernel - Re: [RFC 0/5] ARM: dma-mapping: New dma_map

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 for Android: free password hash cracker in your pocket

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

Message-ID: <505B35F7.2080201@wwwdotorg.org>
Date:	Thu, 20 Sep 2012 09:27:51 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Krishna Reddy <vdumpa@...dia.com>
CC:	Joerg Roedel <joerg.roedel@....com>, Arnd Bergmann <arnd@...db.de>,
	Hiroshi Doyu <hdoyu@...dia.com>,
	"m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"minchan@...nel.org" <minchan@...nel.org>,
	"chunsang.jeong@...aro.org" <chunsang.jeong@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"subashrp@...il.com" <subashrp@...il.com>,
	"linaro-mm-sig@...ts.linaro.org" <linaro-mm-sig@...ts.linaro.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
	"pullip.cho@...sung.com" <pullip.cho@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC 0/5] ARM: dma-mapping: New dma_map_ops to control IOVA more
 precisely

On 09/20/2012 12:40 AM, Krishna Reddy wrote:
>>> On Tegra, the following use cases need specific IOVA mapping.
>>> 1. Few MMIO blocks need IOVA=PA mapping setup.
>>
>> In that case, why would we enable the IOMMU for that one device; IOMMU
>> disabled means VA==PA, right? Perhaps isolation of the device so it can only
>> access certain PA ranges for security?
> 
> The device(H/W controller) need to access few special memory blocks(IOVA==PA)
> and DRAM as well.

OK, so only /some/ of the VA space is VA==PA, and some is remapped;
that's a little different that what you originally implied above.

BTW, which HW module is this; AVP/COP or something else. This sounds
like an odd requirement.

> There is also a case where frame buffer memory is passed from BootLoader to Kernel and
> display H/W  continues to access it with IOMMU enabled. To support this, the one to one
> mapping has to be setup before enabling IOMMU.

Yes, that makes sense.
--
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/