Re: [PATCH v4 2/2] coco: guest: arm64: Drop dummy RSI platform device stub

[Aneesh Kumar K.V <aneesh.kumar@kernel.org>]

Catalin Marinas <catalin.marinas@arm.com> writes:

> + Suzuki again
>
> On Mon, Apr 27, 2026 at 11:46:15AM +0530, Aneesh Kumar K.V (Arm) wrote:
>> The SMCCC firmware driver now creates the `arm-smccc` platform device
>> and also creates the CCA auxiliary devices once the RSI ABI is
>> discovered. This makes the arch-specific arm64_create_dummy_rsi_dev()
>> helper redundant. Remove the arm-cca-dev platform device registration
>> and let the SMCCC probe manage the RSI device.
>> 
>> systemd match on platform:arm-cca-dev for confidential vm detection [1].
>> Losing the platform device registration can break that. Keeping this
>> removal in its own change makes it easy to revert if that regression
>> blocks the rollout.
>> 
>> [1] https://lore.kernel.org/all/4a7d84b2-2ec4-4773-a2d5-7b63d5c683cf@arm.com
>
> I wouldn't merge this now given that systemd checks this file. Could we
> have a symbolic link instead for some time until systemd eventually gets
> updated (years?).
>

I’ll add this in the next revision.

static int create_rsi_compat_link(struct device *target_dev)
{
	struct kobject *platform_kobj;
	/*
	 * target_dev is:
	 * /sys/devices/platform/arm-smccc/arm_cca_guest.arm-rsi-dev.0
	 * Create compat link /sys/devices/platform/arm-cca-dev
	 */
	platform_kobj = target_dev->kobj.parent->parent;

	return sysfs_create_link(platform_kobj,
				 &target_dev->kobj,
				 "arm-cca-dev");
}

-aneesh