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

Jeremy Linton
2025-10-10T15:50:06Z

On 10/10/25 10:30 AM, 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.

Yes, I agree, its just at the time the statment was around what is the
most reliable early indicator, and since there isn't a hwcap or anything
that ended up being the choice, as disgusting as it is.

Presumably once all this works out the sysfs/api surface will be more
'defined'

>
> Jason