PCI passthrough to PV guests no longer possible without IOMMU support on Xen 4.13

[Gabor Hudiczius <ghudiczius@xxxxxxxxx>]

Hi,


I've recently updated from Xen 4.12 to 4.13 and it seems that PCI 
passthrough without IOMMU is no longer supported.
I have an old Proliant DL380 G3 that has no IOMMU support (xl dmesg: 
(XEN) I/O virtualisation disabled), on which I used to pass a PCI 
network card to one of my DomUs, but since updating to 4.13 I get the 
following error message: "libxl: error: 
libxl_create.c:979:libxl__domain_config_setdefault: passthrough not 
supported on this platform"
As I see, the source of this issue is in libxl_create.c [0] where a 
check has been introduced which will fail if passthrough is enabled 
(either explicitly or by specifying at least one pci device to pass 
through) and IOMMU is disabled.

Not sure if it was an intentional change or an oversight, but I would be 
grateful for any workaround.

Regards,

Gabor


[0]: 
http://xenbits.xenproject.org/gitweb/?p=xen.git;a=blob;f=tools/libxl/libxl_create.c;h=2814818e34d2764b8ea242d4177c29bdebe9159c;hb=456957aaa1391e0dfa969e2dd97b87c51a79444e#l1106

p.s.: I wasn't sure whether to post it here, or xen-devel, I hope this 
list is the right one for this question.