0

I have a Gigabyte GA-970A-DS3P board with a AMD FX(tm)-8350 cpu. I have IOMMU enabled in the BIOS. For the non-XEN linux boot I pass iommu=pt amd_iommu_dump as a kernel argument and can verify that AMD-V is loaded via dmsg | grep AMD-V. When running a QEMU/KVM guest I can passthrough the Marvell 88SE9230 card to the guest and everything works fine.

I want to get this pass-through working with a XEN setup as well. However from the 4 SATA 0-3 ports that the 88SE9230 card supplies only the last port is actually discovering a disk (i.e. if port 0 and 1 are connected, then disk on port 1 is discovered, while port 0 remains empty).

I now run Xen 4.9 via apt-get install xen-hypervisor-4.9-amd64 in an Ubuntu-18.04 dom0. Kernel is 4.15.0-29-generic. I rebind my device (in my case 0000:01:00.0) via pciback.sh as described here and rebind via pciback.sh "0000:01:00.0". Then I can attach 0000:01:00.0 to the Xen guest.

Inside the guest 0000:01:00.0 appears and lspci and pciconf (in my case the XEN guest is FreBSD FreeNAS) works correctly. However only the disk on the last connected port is detected. All other ports seems to be empty even if I have a disk connected. In the KVM version these disks are recognized.

I was wondering where the AMD iommu handling is implemented in the Xen case. The Ubuntu 18.04 dom0 doesnt have any iommu entries in sysfs and the AMD-V debug messages are not printed. So I guess there is a baremetal XEN hypervisor that implements the iommu initialization. Is there some option I need to add to enable AMD iommu handling in the hypervisor (equivalent to the linux iommu=pt option) and how is this done?

0

The standard Xen emulated IDE will appear as ada0 while the passthrough SATA device will also appear as ada0. This results in one disk shadowing the other. In /dev/ only one ada0 entry will be seen.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.