The PSCI v1.3 spec (https://developer.arm.com/documentation/den0022, currently in Alpha state, hence 'RFC') adds support for a SYSTEM_OFF2 function enabling a HIBERNATE_OFF state which is analogous to ACPI S4. 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). This updates KVM to support advertising PSCI v1.3, and unconditionally enables the SYSTEM_OFF2 support when PSCI v1.3 is enabled. For now, KVM defaults to PSCI v1.2 unless explicitly requested. For the guest side, add a new SYS_OFF_MODE_POWER_OFF handler with higher priority than the EFI one, but which *only* triggers when there's a hibernation in progress. There are other ways to do this (see the commit message for more details) but this seemed like the simplest. Version 2 of the patch series splits out the psci.h definitions into a separate commit (a dependency for both the guest and KVM side), and adds definitions for the other new functions added in v1.3. It also moves the pKVM psci-relay support to a separate commit; although in arch/arm64/kvm that's actually about the *guest* side of SYSTEM_OFF2 (i.e. using it from the host kernel, relayed through nVHE). Version 3 dropped the KVM_CAP which allowed userspace to explicitly opt in to the new feature like with SYSTEM_SUSPEND, and makes it depend only on PSCI v1.3 being exposed to the guest. David Woodhouse (5): firmware/psci: Add definitions for PSCI v1.3 specification (ALPHA) KVM: arm64: Add support for PSCI v1.2 and v1.3 KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function for hibernation KVM: arm64: nvhe: Pass through PSCI v1.3 SYSTEM_OFF2 call arm64: Use SYSTEM_OFF2 PSCI call to power off for hibernate Documentation/virt/kvm/api.rst | 11 +++++++++ arch/arm64/include/uapi/asm/kvm.h | 6 +++++ arch/arm64/kvm/hyp/nvhe/psci-relay.c | 2 ++ arch/arm64/kvm/hypercalls.c | 2 ++ arch/arm64/kvm/psci.c | 43 +++++++++++++++++++++++++++++++++++- drivers/firmware/psci/psci.c | 35 +++++++++++++++++++++++++++++ include/kvm/arm_psci.h | 4 +++- include/uapi/linux/psci.h | 20 +++++++++++++++++ kernel/power/hibernate.c | 5 ++++- 9 files changed, 125 insertions(+), 3 deletions(-)
