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

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

>> >> 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; Didn't find more comments below, so I truncate the mail.