[PATCH v4][PART 1 0/4] Enable guest suspend/resume support on ARM via vPSCI

[Mykola Kvach <xakep.amatop@xxxxxxxxx>]

From: Mykola Kvach <mykola_kvach@xxxxxxxx>

This patch series introduces the initial support for guest suspend
and resume on ARM platforms using the PSCI SYSTEM_SUSPEND interface. The main
goal is to allow ARM guests to request suspension using PSCI and be resumed
by the control domain (e.g., via "xl resume").

### Background

The PSCI SYSTEM_SUSPEND call is part of the PSCI v1.0+ specification and is
used by guests to enter the deepest possible power state. On Xen/ARM, we
emulate this interface in the virtual PSCI (vPSCI) layer for guests.

This series includes:

1. A new vPSCI implementation of the PSCI SYSTEM_SUSPEND function for guests
2. Documentation updates to SUPPORT.md to reflect PSCI and vPSCI support status
3. Enabling "xl resume" command compilation for ARM, which was previously 
disabled

### Usage

For Linux-based guests:
  - Suspend can be triggered using: "echo mem > /sys/power/state" or "systemctl 
suspend"
  - Resume can be performed from control domain using: "xl resume <domain>"

For more information, refer to the official Linux kernel documentation on power 
management.

Note that currently, SYSTEM_SUSPEND is supported only for guest domains (not for
the hardware domain), and behaves as a logical standby. More details can be 
found in
the appropriate commit message and in the code comments.
---

TODO: enable "xl suspend" for ARM
---
Previous versions of this patch series:
  V1: https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg01093.html
  V2: https://marc.info/?l=xen-devel&m=166514782207736&w=2
  V3: https://lists.xenproject.org/archives/html/xen-devel/2025-03/msg00168.html


This is the first part of previous patch series and originally consist only
with necessary changes needed for guest domain suspend.

Mykola Kvach (4):
  tools/xl: allow resume command compilation for arm
  xen/arm: Implement PSCI SYSTEM_SUSPEND call for guests
  SUPPORT.md: Document ARM PSCI and vPSCI support
  CHANGELOG: Mention Xen suspend/resume to RAM feature on arm64

 CHANGELOG.md                          |  1 +
 SUPPORT.md                            | 15 +++++++
 tools/include/libxl.h                 |  1 -
 tools/xl/xl.h                         |  2 +-
 tools/xl/xl_cmdtable.c                |  2 +-
 tools/xl/xl_vmcontrol.c               | 12 ++---
 xen/arch/arm/include/asm/perfc_defn.h |  1 +
 xen/arch/arm/include/asm/psci.h       |  2 +
 xen/arch/arm/vpsci.c                  | 64 +++++++++++++++++++++++++++
 9 files changed, 91 insertions(+), 9 deletions(-)

-- 
2.48.1