Re: [PATCH V3 1/2] xen: Update dm_op.h from Xen public header

[Juergen Gross <jgross@xxxxxxxx>]

On 25.07.23 09:49, Jan Beulich wrote:
> On 25.07.2023 09:42, Viresh Kumar wrote:
> > On 25-07-23, 09:18, Jan Beulich wrote:
> > > I question that use, btw, but it is not up to me to decide whether to
> > > accept such a layering violation in Linux. dm-op is, as its name says,
> > > for device models to use. Your intended use doesn't fall in that
> > > category, aiui. Imo the present contents of dm_op.h in Linux is indeed
> > > all a kernel is supposed to know about, unless it was to gain in-kernel
> > > device models.
> > Is there any other way by which an interrupt can be raised for the
> > guest VM ? I was only aware of this method and so implemented it like
> > this.
> >
> > I am open to suggestions on this.
> Well. I don't know your requirements. Generally I would suggest using
> event channels, not interrupts, when talking about injecting events
> into guests. If it strictly needs to be an interrupt, then I guess a
> non-dm-op means would need introducing if none already exists.
I think the best way would be to let the user mode device model (i.e. the
backend) construct the dm-op parameters like qemu is doing it and pass it
via the ioctl to the privcmd driver as part of struct privcmd_irqfd. Then
it would be opaque to the kernel like every other dm-op.


Juergen

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