This module will be dedicated to DeviceNode and DeviceTree definitions
along with some dedicated unit tests.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This iterator will let the VMM enumerate the resources associated
with the DeviceManager, allowing for introspection.
Moreover, by implementing a double ended iterator, we can get the
hierarchy from the leaves to the root of the tree, which is very
helpful in the context of restoring the devices in the right order.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that the device tree fully replaced the need for a dedicated list of
migratable devices, this commit cleans up the codebase by removing it
from the DeviceManager.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit switches from migratable_devices to device_tree in order to
restore devices exclusively based on the device tree.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit adds an extra field to the DeviceNode so that the structure
can hold a Migratable device. The long term plan is to be able to remove
the dedicated table of migratable devices, but instead rely only on the
device tree.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In order to hide the complexity chosen for the device tree stored in
the DeviceManager, we introduce a new DeviceTree structure.
For now, this structure is a simple passthrough of a HashMap, but it can
be extended to handle some DeviceTree specific operations.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This device has a dedicated memory region in the guest address space,
which means in case of snapshot/restore, it must be restored in the
exact same location it was during the snapshot.
That's through the resources that we can describe the location of this
extra memory region, allowing the device for correct restoring.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This device has a dedicated memory region in the guest address space,
which means in case of snapshot/restore, it must be restored in the
exact same location it was during the snapshot.
That's through the resources that we can describe the location of this
extra memory region, allowing the device for correct restoring.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the device tree, retrieve the resources associated with a
virtio-mmio device to restore it at the right location in guest address
space. Also, the IRQ number is correctly restored.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Instead of splitting the MMIO allocation and the device creation into
separate functions for virtio-mmio devices, it's is easier to move
everything into the same function as we'll be able to gather resources
in the same place for the same device.
These resources will be stored in the device tree in a follow up patch.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In case the VM is created from scratch, the devices should be created
after the DeviceManager has been created. But this should not affect the
restore codepath, as in this case the devices should be created as part
of the restore() function.
It's necessary to perform this differentiation as the restore must go
through the following steps:
- Create the DeviceManager
- Restore the DeviceManager with the right state
- Create the devices based on the restored DeviceManager's device tree
- Restore each device based on the restored DeviceManager's device tree
That's why this patch leverages the recent split of the DeviceManager's
creation to achieve what's needed.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit performs the split of the DeviceManager's creation into two
separate functions by moving anything related to device's creation after
the DeviceManager structure has been initialized.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Based on the device tree, we now ensure the restore can be done in the
right order, as it will respect the dependencies between nodes.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The DeviceManager itself must be snapshotted in order to store the
information regarding the devices associated with it, which effectively
means we need to store the device tree.
The mechanics to snapshot and restore the DeviceManagerState are added
to the existing snapshot() and restore() implementations.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The DeviceManager now creates a tree of devices in order to store the
resources associated with each device, but also to track dependencies
between devices.
This is a key part for proper introspection, but also to support
snapshot and restore correctly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
It's not possible to call UnixListener::Bind() on an existing file so
unlink the created socket when shutting down the Vsock device.
This will allow the VM to be rebooted with a vsock device.
Fixes: #1083
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Generate an error during validation if an attempt it made to place a
device behind an IOMMU or using a VFIO device when not using PCI.
Fixes: #751
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Let's put an underscore "_" in front of each device name to identify
when it has been set internally.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The virtio-console was not added to the list of Migratable devices,
which is fixed from this patch.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
It is based off the name from the virtio device attached to this
transport layer.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
It is based off the name from the virtio device attached to this
transport layer.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Because we know we will need every virtio device to be identified with a
unique id, we can simplify the code by making the identifier mandatory.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This identifier is chosen from the DeviceManager so that it will manage
all identifiers across the VM, which will ensure uniqueness.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Even in the context of "mmio" feature, we need the next device name to
be generated as we need to identify virtio-mmio devices to support
snapshot and restore functionalities.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will be later used to identify each device used by the VM in order
to perform introspection and snapshot/restore properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will be later used to identify each device used by the VM in order
to perform introspection and snapshot/restore properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will be later used to identify each device used by the VM in order
to perform introspection and snapshot/restore properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will be later used to identify each device used by the VM in order
to perform introspection and snapshot/restore properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This will be later used to identify each device used by the VM in order
to perform introspection and snapshot/restore properly.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
If the virtio-console device is supposed to be placed behind the virtual
IOMMU, this must be explicitly propagated through the code.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
If the virtio-rng device is supposed to be placed behind the virtual
IOMMU, this must be explicitly propagated through the code.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
If the virtio-vsock device is supposed to be placed behind the virtual
IOMMU, this must be explicitly propagated through the code.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that all virtio devices are assigned with identifiers, they could
all be removed from the VM. This is not something that we want to allow
because it does not make sense for some devices. That's why based on the
device type, we remove the device or we return an error to the user.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
By giving the devices ids this effectively enables the removal of the
device.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The parameters regarding the attachment to the virtio-iommu device was
not propagated correclty, and any modification to the configuration was
not stored back into it.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
It's possible to have multiple vsock devices so in preparation for
hotplug/unplug it is important to be able to have a unique identifier
for each device.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
If the current state is paused that means most of the handles got killed by pthread_kill
We need to unpark those threads to make the shutdown worked. Otherwise
The shutdown API hangs and the API is not responding afterwards. So
before the shutdown call we need to resume the VM make it succeed.
Fixes: #817
Signed-off-by: Muminul Islam <muislam@microsoft.com>
If a size is specified use it (in particular this is required if the
destination is a directory) otherwise seek in the file to get the size
of the file.
Add a new check that the size is a multiple of 2MiB otherwise the kernel
will reject it.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Check that if any device using vhost-user (net & disk with
vhost_user=true) or virtio-fs is enabled then check shared memory is
also enabled.
Fixes: #848
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The new 'shared' and 'hugepages' controls aim to replace the 'file'
option in MemoryConfig. This patch also updated all related integration
tests to use the new controls (instead of providing explicit paths to
"/dev/shm" or "/dev/hugepages").
Fixes: #1011
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Signed-off-by: Bo Chen <chen.bo@intel.com>
Replace alignment calculation of start address with functionally
equivalent version that does not assume that the block size is a power
of two.
Signed-off-by: Martin Xu <martin.xu@intel.com>
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When a virtio device is dynamically removed from the VM through the
hot-unplug mechanism, every mapping associated with it must be properly
removed.
Based on the previous patches letting a VirtioDevice expose the list of
userspace mappings associated with it, this patch can now remove all the
KVM userspace memory regions through the MemoryManager.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The same way we added a helper for creating userspace memory mappings
from the MemoryManager, this patch adds a new helper to remove some
previously added mappings.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
When hot-unplugging the virtio-pmem from the VM, we don't remove the
associated userspace mapping. This patch will let us fix this in a
following patch. For now, it simply adapts the code so that the Pmem
device knows about the mapping associated with it. By knowing about it,
it can expose it to the caller through the new userspace_mappings()
function.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The hotplugged virtio devices were not added to the list of virtio
devices from the DeviceManager. This patch fixes it, as it was causing
hotplugged virtio-fs devices from not supporting memory hotplug, since
they were never getting the update as they were not part of the list of
virtio devices held by the DeviceManager.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Adds DeviceManager method `make_virtio_fs_device` which creates a single
device, and modifies `make_virtio_fs_devices` to use this method.
Implements the new `vm.add-fs route`.
Signed-off-by: Dean Sheather <dean@coder.com>
Currently unimplemented. Once implemented, this API will allow for
creating virtio-fs devices in the VM after it has booted.
Signed-off-by: Dean Sheather <dean@coder.com>
In the context of the shared memory region used by virtio-fs in order to
support DAX feature, the shared region is exposed as a dedicated PCI
BAR, and it is backed by a KVM userspace mapping.
Upon BAR remapping, the BAR is moved to a different location in the
guest address space, and the KVM mapping must be updated accordingly.
Additionally, we need the VirtioDevice to report the updated guest
address through the shared memory region returned by get_shm_regions().
That's why a new setter is added to the VirtioDevice trait, so that
after the mapping has been updated for KVM, we can tell the VirtioDevice
the new guest address the shared region is located at.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The order the elements are pushed into the list is important to restore
them in the right order. This is particularly important for MmioDevice
(or VirtioPciDevice) and their VirtioDevice counterpart.
A device must be fully ready before its associated transport layer
management can trigger its restoration, which will end up activating the
device in most cases.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
OVMF and other standard firmwares use I/O port 0x402 as a simple debug
port by writing ASCII characters to it. This is gated under a feature
that is not enabled by default.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
We now support assigning device ids for VFIO and virtio-pci devices so
this error can be generalised.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Extend the eject_device() method on DeviceManager to also support
virtio-pci devices being unplugged.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
In order to support hotplugging there is a map of human readable device
id to PCI BDF map.
As the device id is part of the specific device configuration (e.g.
NetConfig) it is necessary to return the id through from the helper
functions that create the devices through to the functions that add
those devices to the bus. This necessitates changing a great deal of
function prototypes but otherwise has little impact.
Currently only if an id is supplied by the user as part of the device
configuration is it populated into this map. A later commit will
populate with an autogenerated name where none is supplied by the user.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Now that ownership of the memory regions used for the virtio-pmem and
vhost-user-fs devices have been moved into those devices it is no longer
necessary to track them inside DeviceManager.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Move the release of the managed memory region from the DeviceManager to
the vhost-user-fs device. This ensures that the memory will be freed when
the device is unplugged which will lead to it being Drop()ed.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Move the release of the managed memory region from the DeviceManager to
the virtio-pmem device. This ensures that the memory will be freed when
the device is unplugged which will lead to it being Drop()ed.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
While testing self spawned vhost-user backends, it appeared that the
backend was aborting due to a missing system call in the seccomp
filters. mremap() was the culprit and this patch simply adds it to the
whitelist.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This should make it a pointer in the Go generated code so that it will
be ommitted and thus not populated with an unhelpful default value.
Fixes: #1015
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This ensures that the field is filled with None when it is not specified
as part of the deserialisation step.
Fixes: #1015
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
We can now allow guests that specify an initramfs to boot
using the PVH boot protocol.
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
This allows the validation of this requirement for both command line
booted VMs and those booted via the API.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This allows the validation of this requirement for both command line
booted VMs and those booted via the API.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Replace the existing VmConfig::valid() check with a call into
.validate() as part of earlier config setup or boot API checks.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
When performing an API boot validate the configuration. For now only
some very basic validation is performed but in subsequent commits
the validation will be extended.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The configuration comes from a variety of places (commandline, REST API
and restore) however some validation was only happening on the command
line parsing path. Therefore introduce a new ability to validate the
configuration before proceeding so that this can be used for commandline
and API boots.
For now move just the console and serial output mode validation under
the new validation API.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Making sure the OpenAPI definition is up to date with newly added
structure and parameters to support VM restoration.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that the restore path uses RestoreConfig structure, we add a new
parameter called "prefault" to it. This will give the user the ability
to populate the pages corresponding to the mapped regions backed by the
snapshotted memory files.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The goal here is to move the restore parameters into a dedicated
structure that can be reused from the entire codebase, making the
addition or removal of a parameter easier.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
When CoW can be used, the VM restoration time is reduced, but the pages
are not populated. This can lead to some slowness from the guest when
accessing these pages.
Depending on the use case, we might prefer a slower boot time for better
performances from guest runtime. The way to achieve this is to prefault
the pages in this case, using the MAP_POPULATE flag along with CoW.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This patch extends the previous behavior on the restore codepath.
Instead of copying the memory regions content from the snapshot files
into the new memory regions, the VMM will use the snapshot region files
as the backing files behind each mapped region. This is done in order to
reduce the time for the VM to be restored.
When the source VM has been initially started with a backing file, this
means it has been mapped with the MAP_SHARED flag. For this case, we
cannot use the CoW trick to speed up the VM restore path and we simply
fallback onto the copy of the memory regions content.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Whenever a MemoryManager is restored from a snapshot, the memory regions
associated with it might need to directly back the mapped memory for
increased performances. If that's the case, a list of external regions
is provided and the MemoryManager should simply ignore what's coming
from the MemoryConfig.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Now that we can choose specific mmap flags for the guest RAM, we create
a new parameter "copy_on_write" meaning that the memory mappings backed
by a file should be performed with MAP_PRIVATE instead of MAP_SHARED.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In order to anticipate the need for special mmap flags when memory
mapping the guest RAM, we need to switch from from_file() wrapper to
build() wrapper.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
A few KVM ioctls were missing in order to perform both snapshot and
restore while keeping seccomp enabled.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This connects the dots together, making the request from the user reach
the actual implementation for restoring the VM.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This connects the dots together, making the request from the user reach
the actual implementation for snapshotting the VM.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The MemoryManager is somehow a special case, as its restore() function
was not implemented as part of the Snapshottable trait. Instead, and
because restoring memory regions rely both on vm.json and every memory
region snapshot file, the memory manager is restored at creation time.
This makes the restore path slightly different from CpuManager, Vcpu,
DeviceManager and Vm, but achieve the correct restoration of the
MemoryManager along with its memory regions filled with the correct
content.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
This is only implementing the send() function in order to store all Vm
states into a file.
This needs to be extended for live migration, by adding more transport
methods, and also the recv() function must be implemented.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
By aggregating snapshots from the CpuManager, the MemoryManager and the
DeviceManager, Vm implements the snapshot() function from the
Snapshottable trait.
And by restoring snapshots from the CpuManager, the MemoryManager and
the DeviceManager, Vm implements the restore() function from the
Snapshottable trait.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
This implements the send() function of the Transportable trait, so that
the guest memory regions can be saved into one file per region.
This will need to be extended for live migration, as it will require
other transport methods and the recv() function will need to be
implemented too.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
In order to snapshot the content of the guest RAM, the MemoryManager
must implement the Snapshottable trait.
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Implement the Snapshottable trait for Vcpu, and then implements it for
CpuManager. Note that CpuManager goes through the Snapshottable
implementation of Vcpu for every vCPU in order to implement the
Snapshottable trait for itself.
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Anticipating the need for a slightly different function for restoring
vCPUs, this patch factorizes most of the vCPU creation, so that it can
be reused for migration purposes.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
These two new helpers will be useful to capture a vCPU state and being
able to restore it at a later time.
Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
In anticipation for the CpuManager to aggregate all Vcpu snapshots
together, this change makes sure the CpuManager has a handle onto
every vCPU.
Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Based on the list of Migratable devices stored by the DeviceManager, the
DeviceManager can implement the Snapshottable trait by aggregating all
devices snapshots together.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Serial and Ioapic both implement the Migratable trait, hence the
DeviceManager can store them in the list of Migratable devices.
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
We need the project to rely on kvm-bindings and kvm-ioctls branches
which include the serde derive to be able to serialize and deserialize
some KVM structures.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
The parse_size helper function can now be consolidated into the
ByteSized FromStr implementation.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Now all parsing code makes use of the Toggle and it's FromStr support
move the helper function into the from_str() implementation.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The integration tests and documentation make use of empty value strings
like "--net tap=" accept them but return None so that the default value
will be used as expected.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
