Re: [PATCH v8 6/6] coco: guest: arm64: Replace dummy CCA device with sysfs ABI
Suzuki K Poulose <[email protected]>
| Newsgroups | dev.linux.lists.linux-coco,org.infradead.lists.linux-arm-kernel,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
On 07/07/2026 09:13, Aneesh Kumar K.V (Arm) wrote: > The SMCCC firmware driver now creates the arm-smccc platform device and > instantiates the CCA RSI auxiliary devices once the RSI ABI is discovered. > The arm64-specific arm-cca-dev platform device stub is therefore no longer > needed. > > However, userspace has used the arm-cca-dev platform device to detect Arm > CCA Realm guests [1]. Removing it without a replacement would break that > detection and would also leave userspace depending on kernel device-model > details. > > Add /sys/firmware/cca/realm_guest as a stable, architecture-provided ABI > for detecting whether the kernel is running as an Arm CCA Realm guest. The > file returns 1 in Realm world and 0 otherwise, similar to the existing s390 > /sys/firmware/uv/prot_virt_guest interface for protected virtualization > guests. > > Remove the dummy arm-cca-dev registration now that userspace has a > dedicated CCA Realm guest indicator, and document the new ABI in > Documentation/ABI/testing/sysfs-firmware-cca. > > [1] https://lore.kernel.org/all/[email protected] > > Signed-off-by: Aneesh Kumar K.V (Arm) <[email protected]> Acked-by: Suzuki K Poulose <[email protected]>