Re: arm: DomU Networking enable leads to Dom0 kernel oops

[Julien Grall <julien.grall.oss@xxxxxxxxx>]

On Sat, 25 Apr 2020 at 10:49, Julien Grall <julien.grall.oss@xxxxxxxxx> wrote:
>
> On Sat, 25 Apr 2020 at 03:01, Stefano Stabellini <sstabellini@xxxxxxxxxx> 
> wrote:
> > [   86.900974] ------------[ cut here ]------------
> > [   86.905134] Interrupt for port 6, but apparently not enabled; per-user 
> > (____ptrval____)
> > [   86.913228] WARNING: CPU: 0 PID: 2437 at drivers/xen/evtchn.c:167 
> > evtchn_interrupt+0xfc/0x108
>
> The implementation of the evtchn_interrupt() is relying to be called
> in the top-half. On RT, interrupts handlers are forced to be threaded
> and use the IRQF_ONESHOT semantics if they were not threaded before.
>
> However, IRQF_ONESHOT is completely broken for event channels (this is
> not RT's fault) and hence why you see the warning here.
>
> Note that you can't force to run evtchn_interrupt() in the top-half
> because it relies on functions that may sleep.
>
> See https://lkml.org/lkml/2019/2/19/642.

Here at better link with the full conversation:

https://lore.kernel.org/lkml/5e256d9a-572c-e01e-7706-407f99245b00@xxxxxxx/

>
> Cheers,
>
> --
> Julien Grall