[Kimchi-devel] [PATCH v5 4/4] Host device passthrough: List VMs that are holding a host device

[Zhou Zheng Sheng]

Add a "vm_holders" sub-collection under host device resource, so the
front-end can determine if a device is busy or not, and the user can
know which VMs are holding the device.

This patch scans all VM XML to check if a device is hold by a VM. Also
adds a check to keep the host device assigned to only one VM.

Example
  curl -k -u root -H "Content-Type: application/json" \
    -H "Accept: application/json" \
    'https://127.0.0.1:8001/host/devices/usb_1_1_6/vm_holders
Should output a list like following.
  [
    {
      "state":"shutoff",
      "name":"fedora20"
    },
    {
      "state":"running",
      "name":"f20xfce-slave"
    }
  ]

If there is no VM holding the device, it prints an empty list [].

v5:
  When assigning a device to VM, check if there are other VMs holding
the device and raise an exception. Move the VMHoldersModel to
vmhostdevs.py to avoid circular import problem.

Signed-off-by: Zhou Zheng Sheng <zhshzhou at linux.vnet.ibm.com>
---
 src/kimchi/control/host.py     |  7 +++++++
 src/kimchi/i18n.py             |  2 ++
 src/kimchi/model/vmhostdevs.py | 24 ++++++++++++++++++++++++
 3 files changed, 33 insertions(+)

diff --git a/src/kimchi/control/host.py b/src/kimchi/control/host.py
index 15f2343..efc31ea 100644
--- a/src/kimchi/control/host.py
+++ b/src/kimchi/control/host.py
@@ -110,11 +110,18 @@ class PassthroughAffectedDevices(Collection):
         self.model_args = (device_id, )
 
 
+class VMHolders(SimpleCollection):
+    def __init__(self, model, device_id):
+        super(VMHolders, self).__init__(model)
+        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)
+        self.vm_holders = VMHolders(self.model, id)
 
     @property
     def data(self):
diff --git a/src/kimchi/i18n.py b/src/kimchi/i18n.py
index 3c31ab6..8e4b041 100644
--- a/src/kimchi/i18n.py
+++ b/src/kimchi/i18n.py
@@ -95,6 +95,8 @@ messages = {
                         "Please enable Intel VT-d or AMD IOMMU in your BIOS, then verify the Kernel is compiled with IOMMU support. "
                         "For Intel CPU, add intel_iommu=on to your Kernel parameter in /boot/grub2/grub.conf. "
                         "For AMD CPU, add iommu=pt iommu=1."),
+    "KCHVMHDEV0004E": _("The host device %(dev_name)s should be assigned to just one VM. "
+                        "Currently the following VM(s) are holding the device: %(names)s."),
 
     "KCHVMIF0001E": _("Interface %(iface)s does not exist in virtual machine %(name)s"),
     "KCHVMIF0002E": _("Network %(network)s specified for virtual machine %(name)s does not exist"),
diff --git a/src/kimchi/model/vmhostdevs.py b/src/kimchi/model/vmhostdevs.py
index 9e59513..817a054 100644
--- a/src/kimchi/model/vmhostdevs.py
+++ b/src/kimchi/model/vmhostdevs.py
@@ -119,6 +119,11 @@ class VMHostDevsModel(object):
             DevicesModel(conn=self.conn).get_list(_passthrough='true')
         if dev_name not in eligible_dev_names:
             raise InvalidParameter('KCHVMHDEV0002E', {'dev_name': dev_name})
+        holders = VMHoldersModel(conn=self.conn).get_list(dev_name)
+        if holders:
+            names = ', '.join([holder['name'] for holder in holders])
+            raise InvalidOperation('KCHVMHDEV0004E', {'dev_name': dev_name,
+                                                      'names': names})
 
     def create(self, vmid, params):
         dev_name = params['name']
@@ -301,3 +306,22 @@ class VMHostDevModel(object):
                 xmlstr = etree.tostring(e)
                 dom.detachDeviceFlags(
                     xmlstr, get_vm_config_flag(dom, mode='all'))
+
+
+class VMHoldersModel(object):
+    def __init__(self, **kargs):
+        self.conn = kargs['conn']
+
+    def get_list(self, device_id):
+        devsmodel = VMHostDevsModel(conn=self.conn)
+
+        conn = self.conn.get()
+        doms = conn.listAllDomains(0)
+
+        res = []
+        for dom in doms:
+            dom_name = dom.name()
+            if device_id in devsmodel.get_list(dom_name):
+                state = DOM_STATE_MAP[dom.info()[0]]
+                res.append({"name": dom_name, "state": state})
+        return res
-- 
1.9.3