Re: frontend and backend devices and different types of hw - pci for example

[Sting Zax <zstingx@gmail.com>]

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.williamson@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
>