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

Aline Manera alinefm at linux.vnet.ibm.com
Sun Jul 13 14:43:02 UTC 2014



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 at linux.vnet.ibm.com>
> ---
>   src/kimchi/control/host.py |   9 ++++
>   src/kimchi/hostdev.py      | 106 +++++++++++++++++++++++++++++++++++++++++++++
>   src/kimchi/model/host.py   |  17 +++++++-
>   3 files changed, 131 insertions(+), 1 deletion(-)
>
> diff --git a/src/kimchi/control/host.py b/src/kimchi/control/host.py
> index ebf1bed..15f2343 100644
> --- a/src/kimchi/control/host.py
> +++ b/src/kimchi/control/host.py
> @@ -103,9 +103,18 @@ class Devices(Collection):
>           self.resource = Device
>
>
> +class PassthroughAffectedDevices(Collection):
> +    def __init__(self, model, device_id):
> +        super(PassthroughAffectedDevices, self).__init__(model)
> +        self.resource = Device
> +        self.model_args = (device_id, )
> +
> +
>   class Device(Resource):
>       def __init__(self, model, id):
>           super(Device, self).__init__(model, id)
> +        self.passthrough_affected_devices = \
> +            PassthroughAffectedDevices(self.model, id)
>
>       @property
>       def data(self):
> diff --git a/src/kimchi/hostdev.py b/src/kimchi/hostdev.py
> index 0785802..babde92 100644
> --- a/src/kimchi/hostdev.py
> +++ b/src/kimchi/hostdev.py
> @@ -17,6 +17,8 @@
>   # License along with this library; if not, write to the Free Software
>   # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
>
> +import os
> +
>   from kimchi.model.libvirtconnection import LibvirtConnection
>   from kimchi.utils import kimchi_log
>   from kimchi.xmlutils import dictize
> @@ -46,6 +48,107 @@ def _get_dev_info_tree(dev_infos):
>       return root
>
>
> +def _strip_parents(devs, dev):
> +    parent = dev['parent']
> +    while parent is not None:
> +        try:
> +            parent_dev = devs.pop(parent)
> +        except KeyError:
> +            break
> +
> +        if (parent_dev['device_type'],
> +                dev['device_type']) == ('usb_device', 'scsi'):
> +            # For USB device containing mass storage, passthrough the
> +            # USB device itself, not the SCSI unit.
> +            devs.pop(dev['name'])
> +            break
> +
> +        parent = parent_dev['parent']
> +
> +
> +def _is_pci_qualified(pci_dev):
> +    # PCI class such as bridge and storage controller are not suitable to
> +    # passthrough to VM, so we make a whitelist and only passthrough PCI
> +    # class in the list.
> +
> +    whitelist_pci_classes = {
> +        # Refer to Linux Kernel code include/linux/pci_ids.h
> +        0x000000: {  # Old PCI devices
> +            0x000100: None},  # Old VGA devices
> +        0x020000: None,  # Network controller
> +        0x030000: None,  # Display controller
> +        0x040000: None,  # Multimedia device
> +        0x080000: {  # System Peripheral
> +            0x088000: None},  # Misc Peripheral, such as SDXC/MMC Controller
> +        0x090000: None,  # Inupt device
> +        0x0d0000: None,  # Wireless controller
> +        0x0f0000: None,  # Satellite communication controller
> +        0x100000: None,  # Cryption controller
> +        0x110000: None,  # Signal Processing controller
> +        }
> +
> +    with open(os.path.join(pci_dev['path'], 'class')) as f:
> +        pci_class = int(f.readline().strip(), 16)
> +
> +    try:
> +        subclasses = whitelist_pci_classes[pci_class & 0xff0000]
> +    except KeyError:
> +        return False
> +
> +    if subclasses is None:
> +        return True
> +
> +    if pci_class & 0xffff00 in subclasses:
> +        return True
> +
> +    return False
> +
> +
> +def get_passthrough_dev_infos():
> +    ''' Get devices eligible to be passed through to VM. '''
> +
> +    dev_infos = _get_all_host_dev_infos()
> +    devs = dict([(dev_info['name'], dev_info) for dev_info in dev_infos])
> +
> +    for dev in dev_infos:
> +        if dev['device_type'] in ('pci', 'usb_device', 'scsi'):
> +            _strip_parents(devs, dev)
> +
> +    def is_eligible(dev):
> +        return dev['device_type'] in ('usb_device', 'scsi') or \
> +            (dev['device_type'] == 'pci' and _is_pci_qualified(dev))
> +
> +    return [dev for dev in devs.itervalues() if is_eligible(dev)]
> +
> +
> +def get_affected_passthrough_devices(passthrough_dev):
> +    devs = dict([(dev['name'], dev) for dev in _get_all_host_dev_infos()])
> +
> +    def get_iommu_group(dev_info):
> +        try:
> +            return int(dev_info['iommuGroup'])
> +        except KeyError:
> +            pass
> +
> +        parent = dev_info['parent']
> +        while parent is not None:
> +            try:
> +                iommuGroup = int(devs[parent]['iommuGroup'])
> +            except KeyError:
> +                pass
> +            else:
> +                return iommuGroup
> +            parent = devs[parent]['parent']
> +
> +        return -1
> +
> +    iommu_group = get_iommu_group(passthrough_dev)
> +
> +    return [dev for dev in get_passthrough_dev_infos()
> +            if dev['name'] != passthrough_dev['name'] and
> +            get_iommu_group(dev) == iommu_group]
> +
> +
>   def get_dev_info(node_dev):
>       ''' Parse the node device XML string into dict according to
>       http://libvirt.org/formatnode.html. '''
> @@ -202,4 +305,7 @@ def _format_dev_node(node):
>
>
>   if __name__ == '__main__':
> +    from pprint import pprint
>       _print_host_dev_tree()
> +    print 'Eligible passthrough devices:'
> +    pprint(get_passthrough_dev_infos())
> diff --git a/src/kimchi/model/host.py b/src/kimchi/model/host.py
> index 106dfb5..de3ac50 100644
> --- a/src/kimchi/model/host.py
> +++ b/src/kimchi/model/host.py
> @@ -279,7 +279,7 @@ class DevicesModel(object):
>       def __init__(self, **kargs):
>           self.conn = kargs['conn']
>
> -    def get_list(self, _cap=None):
> +    def get_list(self, _cap=None, _passthrough=None):
>           conn = self.conn.get()
>           if _cap is None:
>               dev_names = [name.name() for name in conn.listAllDevices(0)]
> @@ -288,6 +288,11 @@ class DevicesModel(object):
>           else:
>               # Get devices with required capability
>               dev_names = conn.listDevices(_cap, 0)
> +
> +        if _passthrough is not None and _passthrough.lower() == 'true':
> +            passthrough_names = [
> +                dev['name'] for dev in hostdev.get_passthrough_dev_infos()]
> +            dev_names = list(set(dev_names) & set(passthrough_names))
>           return dev_names
>
>       def _get_devices_fc_host(self):
> @@ -305,6 +310,16 @@ class DevicesModel(object):
>           return conn.listDevices('fc_host', 0)
>
>
> +class PassthroughAffectedDevicesModel(object):
> +    def __init__(self, **kargs):
> +        self.conn = kargs['conn']
> +
> +    def get_list(self, device_id):
> +        dev_info = DeviceModel(conn=self.conn).lookup(device_id)
> +        affected = hostdev.get_affected_passthrough_devices(dev_info)
> +        return [dev['name'] for dev in affected]
> +
> +
>   class DeviceModel(object):
>       def __init__(self, **kargs):
>           self.conn = kargs['conn']
>




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