Re: [RFC PATCH v1 11/38] KVM: arm64: CCA: register host tsm platform device

Greg KH
2025-10-10T15:37:31Z

On Fri, Oct 10, 2025 at 12:30:46PM -0300, Jason Gunthorpe wrote:
> On Fri, Oct 10, 2025 at 10:28:36AM -0500, Jeremy Linton wrote:
>
> > > So you could use auxiliary_device, you'd consider SMC itself to be the
> > > shared HW block and all the auxiliary drivers are per-subsystem
> > > aspects of that shared SMC interface. It is not a terrible fit for
> > > what it was intended for at least.
> >
> > Turns out that changing any of this, will at the moment break systemd's
> > confidential vm detection, because they wanted the earliest indicator the
> > guest was capable and that turned out to be this platform device.
>
> Having systemd detect a software created platform device sounds
> compltely crazy, don't do that. Make a proper sysfs uapi for such a
> general idea please.

Agreed. Please do NOT abuse platform devices for this, as this is NOT a
platform device. It is a random virtual device that you are wanting to
create out of thin air based on something else.

Trigger off of that "something else" please.

thanks,

greg k-h