在 2021/8/6 下午3:27, Laurent Vivier 写道:
On 06/08/2021 08:25, Jason Wang wrote:
在 2021/8/2 下午4:42, Laurent Vivier 写道:
On 02/08/2021 06:50, Jason Wang wrote:
在 2021/7/30 上午3:19, Laurent Vivier 写道:
Add virtio_queue_disable()/virtio_queue_enable() to disable/enable a queue
by setting vring.num to 0 (or num_default).
This is needed to be able to disable a guest driver from the host side
I suspect this won't work correclty for vhost.
With my test it seems to work with vhost too.
So setting 0 will lead -EINVAL to be returned during VHOST_SET_VRING_NUM. I
think qemu
will warn the failure in this case.
I didn't see any error when I tried. I will check the code.
What's more important, it's not guaranteed to work for the case of vhost-user
or vhost-vDPA.
Perhaps we can target only the vhost host case, as this is used for failover
and usually
the virtio-net device is backed by a bridge on same network as the VFIO device?
Probably not, it should be a general feature that can work for all types
of virtio/vhost backends.
And I believe we should only do this after the per queue enabling/disabling is
supported
by the spec.
(only MMIO support that AFAIK)
I don't want to modify the spec.
I need something that works without modifying existing (old) drivers.
The idea is to be able to disable the virtio-net kernel driver from QEMU if the
driver is
too old (i.e. it doesn't support STANDBY feature).
Setting vring.num to 0 forces the kernel driver to exit on error in the probe
function.
It's what I want: the device is present but disabled (the driver is not loaded).
Any other suggestion?
I think we should probably disable the device instead of doing it per virtqueue.
I tried to use virtio_set_disabled() but it doesn't work.
Perhaps it's too late when I call the function (I need to do that in
virtio_net_set_features()). What I want is to prevent the load of the driver in
the guest
kernel to hide the virtio-net device. Setting vring.num to 0 triggers an error
in the
driver probe function and prevents the load of the driver.
How about fail the validate_features() in this case?
Thanks
Thanks,
Laurent
