11 messages in com.xensource.lists.xen-develRe: [Xen-devel] frontend and backend ...
FromSent OnAttachments
Sting Zax28 Aug 2005 00:27 
Mark Williamson28 Aug 2005 08:24 
Sting Zax28 Aug 2005 23:56 
Keir Fraser29 Aug 2005 01:59 
Mark Williamson29 Aug 2005 03:45 
Stefan Berger29 Aug 2005 12:48 
Mark Williamson03 Sep 2005 10:46 
Stefan Berger03 Sep 2005 11:41 
Mark Williamson03 Sep 2005 20:23 
David Hopwood04 Sep 2005 06:35 
Stefan Berger06 Sep 2005 14:59 
Subject:Re: [Xen-devel] frontend and backend devices and different types of hw - pci for example
From:Sting Zax (zsti@gmail.com)
Date:08/28/2005 11:56:45 PM
List:com.xensource.lists.xen-devel

Hello,

I had looked at the code of 2.0.* under xen/arch/x86 saw pci-irq.c and pci-pc.c and pci-x86.c which as I understand handle pci devices other than net/usb. However, I did not saw such modules in the unstable version. May I ask : is this PCI support for non net/usb PCI devices removed (or temporarily removed) from the unstable version? or maybe I simply missed it ?

Note that giving direct physical access to a PCI device has security implications since the guest can potentially use the cards' DMA capabilities to access all of physical memory.

Will IOMMU support help solving this security problems ?

Regards, Sting

On 8/28/05, Mark Williamson <mark@cl.cam.ac.uk> wrote:

What about other devices ? let's say a PCI sound card (or any other PCI device). Where is the software that should handle it ? I remember I saw somewhere some discussion about PCI configuration space, but I don't remember where.

That code is in Xen itself in Xen 2.0. Xen controls access to the PCI configuration spaces so that guests can only see the devices they have access to. It also controls the IO memory / ports that domains are allowed to access in order to control PCI devices.

Note that giving direct physical access to a PCI device has security implications since the guest can potentially use the cards' DMA capabilities to access all of physical memory. The front/back-style devices do not have this limitation.

Btw, I've laid some groundwork for a virtual sound device but haven't had much time to hack on it yet.

Cheers, Mark

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