Re: [Kimchi-devel] [PATCH v7 2/4] Host device passthrough: List eligible device to passthrough

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 ?

> > 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(a)linux.vnet.ibm.com&gt;