linux-kernel - [PATCH v4 0/6] Add PSCI v1.3 SYSTEM

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Message-ID: <222a439df0a08d48021e80b9cff7aeb373c9b060.camel@infradead.org>
Date: Tue, 24 Sep 2024 17:13:00 +0100
From: David Woodhouse <dwmw2@...radead.org>
To: Paolo Bonzini <pbonzini@...hat.com>, Jonathan Corbet <corbet@....net>, 
 Marc Zyngier <maz@...nel.org>, Oliver Upton <oliver.upton@...ux.dev>, James
 Morse <james.morse@....com>,  Suzuki K Poulose <suzuki.poulose@....com>,
 Zenghui Yu <yuzenghui@...wei.com>, Catalin Marinas
 <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Mark Rutland
 <mark.rutland@....com>, Lorenzo Pieralisi <lpieralisi@...nel.org>, "Rafael
 J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>, Len Brown
 <len.brown@...el.com>, Shuah Khan <shuah@...nel.org>, kvm@...r.kernel.org,
 linux-doc@...r.kernel.org,  linux-kernel@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org,  kvmarm@...ts.linux.dev,
 linux-pm@...r.kernel.org,  linux-kselftest@...r.kernel.org
Subject: [PATCH v4 0/6] Add PSCI v1.3 SYSTEM_OFF2 support for hibernation

(oops, missed --compose on that command line. You can have the cover
letter as a reply instead)

The PSCI v1.3 spec (https://developer.arm.com/documentation/den0022)
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 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.

Version 4 is no longer RFC, as the PSCI v1.3 spec is finally published.
Minor fixes from the last round of review, and an added KVM self test.

David Woodhouse (6):
      firmware/psci: Add definitions for PSCI v1.3 specification
      KVM: arm64: Add PSCI v1.3 SYSTEM_OFF2 function for hibernation
      KVM: arm64: Add support for PSCI v1.2 and v1.3
      KVM: selftests: Add test for PSCI SYSTEM_OFF2
      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                    | 37 +++++++++++++++
 include/kvm/arm_psci.h                          |  4 +-
 include/uapi/linux/psci.h                       | 20 ++++++++
 kernel/power/hibernate.c                        |  5 +-
 tools/testing/selftests/kvm/aarch64/psci_test.c | 61 +++++++++++++++++++++++++
 10 files changed, 188 insertions(+), 3 deletions(-)

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