Message-ID: <4FD1FB49.3020905@siemens.com>
Date: Fri, 08 Jun 2012 15:16:57 +0200
From: Jan Kiszka <jan.kiszka@siemens.com>
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To: "Michael S. Tsirkin" <mst@redhat.com>,
        Dominic Eschweiler <eschweiler@fias.uni-frankfurt.de>
CC: "Hans J. Koch" <hjk@hansjkoch.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        Alex Williamson <alex.williamson@redhat.com>
Subject: Re: [PATCH] uio_pci_generic does not export memory resources
References: <1339156616.3870.9.camel@blech> <20120608130351.GB1964@redhat.com>
In-Reply-To: <20120608130351.GB1964@redhat.com>
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On 2012-06-08 15:03, Michael S. Tsirkin wrote:
>> +    /* set master */
>> +	pci_set_master(pdev);
>> +
>> +    /* set DMA mask */
>> +	err = pci_set_dma_mask(pdev, DMA_BIT_MASK(64));
> 
> uio currently only supports devices which do not
> do DMA.
> 
> DMA from uio controlled devices is a no no unless
> it's behind an IOMMU which can protect us from
> random memory corruptions this could cause.
> 
> In the later case it's OK but we need some code
> to check this and program the IOMMU appropriately.

AKA: VFIO. :)

Dominic, maybe you want to have a look at Alex's work:
https://github.com/awilliam/linux-vfio

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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