Hi, On Tue, Mar 12, 2024 at 01:51:28PM +0000, David Woodhouse wrote: > From: David Woodhouse <dwmw@xxxxxxxxxxxx> > > The PSCI v1.3 specification (alpha) adds support for a SYSTEM_OFF2 function > which is analogous to ACPI S4 state. This will allow hosting environments > to determine that a guest is hibernated rather than just powered off, and > ensure that they preserve the virtual environment appropriately to allow > the guest to resume safely (or bump the hardware_signature in the FACS to > trigger a clean reboot instead). > > The beta version will be changed to say that PSCI_FEATURES returns a bit > mask of the supported hibernate types, which is implemented here. Have you considered doing the PSCI implementation in userspace? The SMCCC filter [*] was added for this exact purpose. There are other features being done in userspace (e.g. vCPU hotplug) built on intercepting hypercalls, this seems to be a reasonable candidate too. [*] https://docs.kernel.org/virt/kvm/devices/vm.html#attribute-kvm-arm-vm-smccc-filter-w-o -- Thanks, Oliver
