When there are no available descriptors in the queue (observed when the
network interface hasn't been brought up by the kernel) stop waiting for
notifications that the TAP fd should be read from.
This avoids a situation where the TAP device has data avaiable and wakes
up the virtio-net thread only for the virtio-net thread not read that
data as it has nowhere to put it.
When there are descriptors available in the queue then we resume waiting
for the epoll event on the TAP fd.
This bug demonstrated itself as 100% CPU usage for cloud-hypervisor
binary prior to the guest network interface being brought up. The
solution was inspired by the Firecracker virtio-net code.
Fixes: #208
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The numbr of bytes read was being incorrectly increased by the potential
length of the end of the sliced data rather than the number of bytes
that was in the range. This caused a panic when the the network was
under load by using iperf.
It's important to note that in the Firecracker code base the function
that read_slice() returns the number of bytes read which is used to
increment this counter. The VM memory version however only returns the
empty unit "()".
Fixes: #166
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The structure of the vmm-sys-util crate has changed with lots of code
moving to submodules.
This change adjusts the use of the imported structs to reference the
submodules.
Fixes: #145
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
The existing code taking care of the epoll loop was too restrictive as
it was propagating the error returned from the epoll_wait() syscall, no
matter what was the error. This causes the epoll loop to be broken,
leading to a non-functional virtio device.
This patch enforces the parsing of the returned error and prevent from
the error propagation in case it is EINTR, which stands for Interrupted.
In case the epoll loop is interrupted, it is appropriate to retry.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
As per the VIRTIO specification, every virtio device configuration can
be updated while the guest is running. The guest needs to be notified
when this happens, and it can be done in two different ways, depending
on the type of interrupt being used for those devices.
In case the device uses INTx, the allocated IRQ pin is shared between
queues and configuration updates. The way for the guest to differentiate
between an interrupt meant for a virtqueue or meant for a configuration
update is tied to the value of the ISR status field. This field is a
simple 32 bits bitmask where only bit 0 and 1 can be changed, the rest
is reserved.
In case the device uses MSI/MSI-X, the driver should allocate a
dedicated vector for configuration updates. This case is much simpler as
it only requires the device to send the appropriate MSI vector.
The cloud-hypervisor codebase was not supporting the update of a virtio
device configuration. This patch extends the existing VirtioInterrupt
closure to accept a type that can be Config or Queue, so that based on
this type, the closure implementation can make the right choice about
which interrupt pin or vector to trigger.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
Because we cannot always assume the irq fd will be the way to send
an IRQ to the guest, this means we cannot make the assumption that
every virtio device implementation should expect an EventFd to
trigger an IRQ.
This commit organizes the code related to virtio devices so that it
now expects a Rust closure instead of a known EventFd. This lets the
caller decide what should be done whenever a device needs to trigger
an interrupt to the guest.
The closure will allow for other type of interrupt mechanism such as
MSI to be implemented. From the device perspective, it could be a
pin based interrupt or an MSI, it does not matter since the device
will simply call into the provided callback, passing the appropriate
Queue as a reference. This design keeps the device model generic.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
In order to provide connectivity through network interface between
host and guest, this patch introduces the virtio-net backend.
This code is based on Firecracker commit
d4a89cdc0bd2867f821e3678328dabad6dd8b767
It is a trimmed down version of the original files as it removes the
rate limiter support. It has been ported to support vm-memory crate
and the epoll handler has been modified in order to run a dedicated
epoll loop from the device itself. This epoll loop runs in its own
dedicated thread.
Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
