Re: [Xen-users] Xen 3.0.3, AMD and PCI passthrough

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Mon, Mar 08, 2010 at 03:46:31PM +0100, Kalle Happonen wrote:
> Hello all,
>
> I'm running Xen on a HP DL385G6 machine. I use Centos 5.4 on the dom0,  
> which comes with the seemingly old 3.0.3 (accoring to rpm) version of  
> xen.(Although another thread just said: RHEL5 has Xen hypervisor version  
> 3.1.2 + tools version 3.0.3.)
>
> The machine runs a pair of AMD Istanbuls (Six-Core AMD Opteron(tm)  
> Processor 2431). I have an Ininiband card on the machine which I would  
> like to pass on to a domU. When I try to attach the pci device to the  
> domu, I get the following output though..
>
> xm pci-attach jade 0000:48:00.0
> Error: failed to assign device: maybe the platform doesn't support VT-d,  
> or VT-d isn't enabled properly?
> Usage: xm pci-attach <Domain> <domain:bus:slot.func> [virtual slot]
>
> Insert a new pass-through pci device.
>
> If I have understood correctly, this new AMDs should support it though.  
> The virtualization option has been enabled in the BIOS.
>
> Looking at xm dmesg, however, I get the following
>
> ...
> (XEN) HVM: SVM enabled
> (XEN) HVM: Hardware Assisted Paging detected and enabled.
> (XEN) I/O virtualisation disabled
> ...
>
> I have tried adding "amd_enable_iommu=1" to grub, but it doesn't seem to  
> help. Is the version of xen too old to support this? If so, how big of a  
> task is it to upgrade xen, and which version would be required? Sticking  
> with the stock version would be nice from the security update point of 
> view.
>

Please paste the full "xm dmesg" log. 
Are you sure your hardware has IOMMU, that is required for IO virtualization? 

Also I think only the very latest Xen versions (aka upcoming Xen 4.0.0) has
support for AMD IOMMUs..

Dunno if Redhat has backported AMD IOMMU support to their Xen version.

-- Pasi


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