On 07/13/2014 11:44 PM, Zhou Zheng Sheng wrote:
on 2014/07/13 22:43, Aline Manera wrote:
On 07/09/2014 04:01 AM, Zhou Zheng Sheng wrote:
This patch adds a '_passthrough=true' filter to /host/devices, so it can filter and shows all devices eligible to passthrough to guest. Theoretically, all PCI, USB and SCSI devices can be assigned to guest directly. However usually all host devices form a tree, if we assign a PCI port/SCSI controller/USB controller to guest, all devices/disks under the controller are assigned as well. In this patch we only present the "leaf" host devices to the user as potential passthrough devices. In other word, the possible devices are wireless network interface, SD card reader, camera, SCSI unit(disk or CD), and so on.
Linux kernel is able to recognize the host IOMMU group layout. If two PCI devices are in the same IOMMU group, it means there are possible interconnections between the devices, and the devices can talk to each other bypassing IOMMU. This implies isolation is not pefect between those devices, so all devices in a IOMMU group must be assigned to guest together. On host that recognizes IOMMU groups, by accessing the URI /host/devices/deviceX/passthrough_affected_devices, it returns a list containing the devices in the same IOMMU group as deviceX.
How to test:
List all types of devices to passthrough curl -k -u root -H "Content-Type: application/json" \ -H "Accept: application/json" \ 'https://127.0.0.1:8001/host/devices?_passthrough=true'
List all eligible PCI devices to passthrough /host/devices?_passthrough=true&_cap=pci
List all USB devices to passthrough /host/devices?_passthrough=true&_cap=usb_device
List all SCSI devices to passthrough /host/devices?_passthrough=true&_cap=scsi
List devices in the same IOMMU group as pci_0000_00_19_0 /host/devices/pci_0000_00_19_0/passthrough_affected_devices
This passthrough_affected_devices seems a filter instead of a new resource.
Couldn't we do: /host/devices/pci_0000_00_19_0?_passthrough=true ?
Thanks Aline. Let me explain why I don't think it's a filter.
/host/devices/pci_0000_00_19_0 is a particular device, it contains information like vendor and product id/name, device sysfs patch, domain, bus, slot function id. All these are simple attributes of this device. The affected devices are a collection containing all devices in the same iommu group as pci_0000_00_19_0. If you think a new sub-collection is not good. I propose using a filter for /host/devices. For example,
/host/devices?_passthrough_group_by=pci_0000_00_19_0
Thanks for the explanation, Zheng Sheng! From my view, your proposal using filter is better than a new sub-collection: /host/devices?_passthrough_group_by=pci_0000_00_19_0
v1: v1 series does not contain this patch.
v2: Deal with calculation "leaf" device and "affected" device.
v3 v4: No change.
v5: Change _passthrough=1 to _passthrough=true in the URI scheme. Filter PCI devices according the PCI class.
v6: Don't passthrough PCI device of class code 07. In modern x86 machine, it's possible that "6 Series/C200 Series Chipset Family MEI Controller" and "6 Series/C200 Series Chipset Family KT Controller" are of this class code. These two devices are not suitable to passthrough to guest. We don't have simple and reliable way to distinguish normal serial controller and host chipset XXX controller. This type of PCI devices also include various serial, parallel, modem, communication controller. Serial and parallel controllers can be re-direct from ttyS0 to QEMU's pty using socat, and there is little performance benefit to directly assign to guest. So it'k ok not to passththrough PCI device of class code 07.
Signed-off-by: Zhou Zheng Sheng <zhshzhou@linux.vnet.ibm.com>
Didn't find more comments below, so I truncate the mail.