CentOS virt - May 2016 - PCI Passthrough not working

I am running Xen 4.6 on CentOS 7 in a Dell Poweredge T430 
I need PCI Passthrough to get USB working. I am following the Xenproject Wiki 
I have enabled the Virtulasation in the BIOS. 
I have xen_pciback as a module 
I have issued the command: 
xl pci-assignable-add 00:1a0.0 and it shows up fine when I issue this xl
pci-assignable-list

I have pci=['00:1a.0'] on the DomU config file 
I have added this iommu=soft and swiotlb=force both together and separately to
the kernel command line
in the DomU (running Debian 8), but I get the same error each time. 

libxl: error: libxl_pci.c:999:do_pci_add: xc_assign_device failed: Operation not
permitted
libxl: error: libxl_create.c:1424:domcreate_attach_pci: libxl_device_pci_add
failed: -3

Can anyone suggest a cure for this? 

Many thanks 
Francis 


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On Thu, May 12, 2016 at 12:11 PM, Francis Greaves <francis at choughs.net>
wrote:
> I am running Xen 4.6 on CentOS 7 in a Dell Poweredge T430
> I need PCI Passthrough to get USB working. I am following the Xenproject
> Wiki
> I have enabled the Virtulasation in the BIOS.
> I have xen_pciback as a module
> I have issued the command:
>
> xl pci-assignable-add 00:1a0.0 and it shows up fine when I issue this xl
> pci-assignable-list
>
> I have pci=['00:1a.0'] on the DomU config file
> I have added this iommu=soft and swiotlb=force both together and separately
> to the kernel command line
> in the DomU (running Debian 8), but I get the same error each time.
>
> libxl: error: libxl_pci.c:999:do_pci_add: xc_assign_device failed:
Operation
> not permitted
> libxl: error: libxl_create.c:1424:domcreate_attach_pci:
libxl_device_pci_add
> failed: -3
Can you please attach the following:
1. The complete domU config file
2. A complete log of the command and all the output
3. The full output of "xl dmesg" just after you run the command

Thanks,
 -George

Dear George please find attached the three files as requested. 
I have used 
iommu=soft 

in the grub command line for the kernel in the domU as explained before. 
many thanks 
Francis 

From: "George Dunlap" <dunlapg at umich.edu> 
To: "francis" <francis at choughs.net>, "centos-virt"
<centos-virt at centos.org>
Sent: Monday, 16 May, 2016 10:29:09 
Subject: Re: [CentOS-virt] PCI Passthrough not working 

On Thu, May 12, 2016 at 12:11 PM, Francis Greaves <francis at choughs.net>
wrote: 
> I am running Xen 4.6 on CentOS 7 in a Dell Poweredge T430 
> I need PCI Passthrough to get USB working. I am following the Xenproject 
> Wiki 
> I have enabled the Virtulasation in the BIOS. 
> I have xen_pciback as a module 
> I have issued the command: 
> 
> xl pci-assignable-add 00:1a0.0 and it shows up fine when I issue this xl 
> pci-assignable-list 
> 
> I have pci=['00:1a.0'] on the DomU config file 
> I have added this iommu=soft and swiotlb=force both together and separately
> to the kernel command line 
> in the DomU (running Debian 8), but I get the same error each time. 
> 
> libxl: error: libxl_pci.c:999:do_pci_add: xc_assign_device failed:
Operation
> not permitted 
> libxl: error: libxl_create.c:1424:domcreate_attach_pci:
libxl_device_pci_add
> failed: -3 
Can you please attach the following: 
1. The complete domU config file 
2. A complete log of the command and all the output 
3. The full output of "xl dmesg" just after you run the command 

Thanks, 
-George 
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