Each virtio thread was reading/draining the pause_evt pipe when
detecting the associated event. Problem is, when a virtio device has
multiple threads, they all share the same pause_evt pipe, which can
prevent some threads from receiving the event. If the first thread to
catch the event is quickly clearing the pipe, some other threads might
simply miss the event and they will not enter the "paused" state as
expected.
This is a behavior that was spotted with virtio-net as it usually uses
2 threads by default (1 for TX/RX queues and 1 for the control queue).
The way to solve this issue is by letting each thread drain the pipe
during the resume codepath, that is after the thread has been unparked.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
The same way the VM and the vCPUs are restored in a paused state, all
devices associated with the device manager must be restored in the same
paused state.
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>
A Snapshottable component can snapshot itself and
provide a MigrationSnapshot payload as a result.
A MigrationSnapshot payload is a map of component IDs to a list of
migration sections (MigrationSection). As component can be made of
several Migratable sub-components (e.g. the DeviceManager and its
device objects), a migration snapshot can be made of multiple snapshot
itself.
A snapshot is a list of migration sections, each section being a
component state snapshot. Having multiple sections allows for easier and
backward compatible migration payload extensions.
Once created, a migratable component snapshot may be transported and this
is what the Transportable trait defines, through 2 methods: send and recv.
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Yi Sun <yi.y.sun@linux.intel.com>
The basic idea of virtio-mem is to provide a flexible, cross-architecture
memory hot plug and hot unplug solution that avoids many limitations
imposed by existing technologies, architectures, and interfaces. More
details can be found in https://lkml.org/lkml/2019/12/12/681.
This commit add virtio-mem device.
Signed-off-by: Hui Zhu <teawater@antfin.com>
