When a total ordering between multiple atomic variables is not required
then use Ordering::Acquire with atomic loads and Ordering::Release with
atomic stores.
This will improve performance as this does not require a memory fence
on x86_64 which Ordering::SeqCst will use.
Add a comment to the code in the vCPU handling code where it operates on
multiple atomics to explain why Ordering::SeqCst is required.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
In order to simplify the transition to VirtioCommon and to avoid needing
to set empty fields derive Default for VirtioCommon.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
There will be some cases where the implementation of the snapshot()
function from the Snapshottable trait will require to modify some
internal data, therefore we make this possible by updating the trait
definition with snapshot(&mut self).
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Using the Rust Barrier mechanism, this patch forces each virtio device
to acknowledge they've been correctly paused before going further.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Instead of passing only the event type through the handle_event()
callback, we make the trait slightly more generic by providing the
epoll event to each virtio device implementation.
This is particularly useful for vsock as it will need the event set.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Migrate to EpollHelper so as to remove code that is duplicated between
multiple virtio devices.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Remove the write_config() implementations that only generate a warning
as that is now done at the VirtioDevice level.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Split the generic virtio code (queues and device type) from the
VirtioDevice trait, transport and device implementations.
This also simplifies the feature handling in vhost_user_backend as the
vm-virtio crate is no longer has any features.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
