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Enable IOMMUFD for VM device passthrough #4004

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Enable IOMMUFD for VM device passthrough #4004

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16 changes: 16 additions & 0 deletions virttest/qemu_devices/qcontainer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4031,9 +4031,25 @@ def hostdev_define_by_params(self, name, params, bus=None):
"failover_pair_id": params.get("vm_hostdev_failover_pair_id"),
}
)
# Use hard code 'iommufd0' here, multiple devices use the same iommufd
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As you mentioned here, multiple devices can use the same one. How about checking the iommufd as an ID? If the iommufd device exists with the same ID, reuse it; if not, create a new one, cause we should also support using different iommufd devices, what do you think?

if params.get("iommufd") == "yes":
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In this code block, all parameters use vm_hostdev prefix, I would suggest align with this.

dev_params["iommufd"] = "iommufd0"
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Currently, the iommufd is only used for VFIO devices, so I have an idea here,

devs = []
...
...
fd_id = params.get("vm_hostdev_iommufd")
if fd_id and not self.get_by_qid(fd_id):
    iommufd = iommufd_object_define_by_params()
    dev_params["iommufd"] = fd_id
    devs.append(iommufd)
...
...
dev = qdevices.QDevice(driver, dev_params, parent_bus=dev_bus)
devs.append(dev)
return devs

If you have any concern, please don't hesitate to raise them.

# TODO: Support vfio-ap and vfio-ccw, currently only for pci devices
dev_bus = bus or {"aobject": params.get("pci_bus", "pci.0")}
dev = qdevices.QDevice(driver, dev_params, parent_bus=dev_bus)
for ext_k, ext_v in params.get_dict("vm_hostdev_extra_params").items():
dev.set_param(ext_k, ext_v)
return dev

def iommufd_object_define_by_params(self, obj_id):
"""
Create iommufd object device by params
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Before creating an iommufd device, it is better to check that /dev/iommu exists.


The iommufd objects cmdlines:
-object iommufd,id=iommufd0

:param obj_id: The id of the QObject device, e.g. iommufd0
:return: the iommufd QObject device
"""
backend, properties = "iommufd", {"id": obj_id}
return qdevices.QObject(backend, properties)
13 changes: 13 additions & 0 deletions virttest/qemu_vm.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1747,6 +1747,16 @@ def __iothread_conflict_check(params):
"'image_iothread_vq_mapping' can NOT be set!"
)

def add_iommufd_descriptor():
"""
Add iommufd into device tree

Use hard code 'iommufd0' here for iommufd object, because
multiple devices can use the same iommufd
"""
obj = devices.iommufd_object_define_by_params('iommufd0')
devices.insert(obj)

# End of command line option wrappers

# If nothing changed and devices exists, return immediately
Expand Down Expand Up @@ -1885,6 +1895,9 @@ def __iothread_conflict_check(params):
if params.get("vm_secure_guest_type"):
add_secure_guest_descriptor(params)

if params.get("iommufd"):
add_iommufd_descriptor()

# no automagic devices please
defaults = params.get("defaults", "no")
if devices.has_option("nodefaults") and defaults != "yes":
Expand Down