linux-kernel - [PATCH v2] ACPI S3 to work under Xen.

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Date:	Thu, 29 Sep 2011 16:16:46 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	linux-kernel@...r.kernel.org, rjw@...k.pl, tglx@...utronix.de,
	hpa@...or.com, x86@...nel.org, len.brown@...el.com,
	joseph.cihula@...el.com, shane.wang@...el.com,
	xen-devel@...ts.xensource.com, linux-pm@...ts.linux-foundation.org,
	tboot-devel@...ts.sourceforge.net, linux-acpi@...r.kernel.org,
	liang.tang@...cle.com, ke.yu@...el.com, kevin.tian@...el.com,
	jeremy@...p.org
Subject: [PATCH v2] ACPI S3 to work under Xen. 

Attached is an [v2] set of patches to enable S3 to work with the Xen hypervisor.

Changes since the RFC posting [http://comments.gmane.org/gmane.linux.acpi.devel/50701] by
Liang Tang:
 - Per review comments added: __unused__ attribute, support for PM1A/B if more than 16-bit,
   copyright/license.
 - Added support for PHYSDEVOP_restore_msi_ext call.

The relationship that Xen has with Linux kernel is symbiotic. The Linux
kernel does the ACPI "stuff" and tells the hypervisor to do the low-level
stuff (such as program the IOAPIC, setup vectors, etc). The realm of
ACPI S3 is more complex as we need to save the CPU state (and Intel TXT
values - which the hypervisor has to do).

The major difficulties we hit was with 'acpi_suspend_lowlevel' - which tweaks
a lot of lowlevel values and some of them are not properly handled by Xen.
Liang Tang has figured which ones of them we trip over (read below) - and he
suggested that perhaps we can provide a registration mechanism to abstract
this away. The reason for all of this is that Linux does not talk to the
BIOS directly - instead it simply walks through the necessary ACPI methods
and then issues hypercall to Xen which then further completes the remaining
suspend steps.

So the attached patches do exactly that - there are two entry points
in the ACPI.

 1). For S3: acpi_suspend_lowlevel -> .. lots of code -> acpi_enter_sleep_state
 2). For S1/S4/S5: acpi_enter_sleep_state

The first naive idea was of abstracting away in the 'acpi_enter_sleep_state'
function the tboot_sleep code so that we can use it too. And low-behold - it
worked splendidly for powering off (S5 I believe)

For S3 that did not work - during suspend the hypervisor tripped over when
saving cr8. During resume it tripped over at restoring the cr3, cr8, idt,
and gdt values.

When I posted the RFC, the feedback I got was to use a higher upper interface
to make the call to the hypervisor. Instead of doing it at the lower pv-ops
case for cr3, cr8, idt, gdt, etc. The code I've to say - is much nicer than
doing it via pv-ops.

Anyhow, please take a look!

Konrad Rzeszutek Wilk (5):
      x86: Expand the x86_msi_ops to have a restore MSIs.
      x86, acpi, tboot: Have a ACPI sleep override instead of calling tboot_sleep.
      xen: Utilize the restore_msi_irqs hook.
      xen/acpi/sleep: Enable ACPI sleep via the __acpi_override_sleep
      xen/acpi/sleep: Register to the acpi_suspend_lowlevel a callback.

Liang Tang (2):
      x86/acpi/sleep: Provide registration for acpi_suspend_lowlevel.
      xen/pci:use hypercall PHYSDEVOP_restore_msi_ext to restore MSI/MSI-X vectors

Yu Ke (1):
      xen/acpi: Domain0 acpi parser related platform hypercall

 arch/ia64/include/asm/xen/interface.h |    1 +
 arch/x86/include/asm/acpi.h           |    6 +-
 arch/x86/include/asm/pci.h            |    9 +
 arch/x86/include/asm/x86_init.h       |    1 +
 arch/x86/include/asm/xen/hypercall.h  |    8 +
 arch/x86/include/asm/xen/interface.h  |    1 +
 arch/x86/kernel/acpi/boot.c           |    6 +
 arch/x86/kernel/acpi/sleep.c          |    4 +-
 arch/x86/kernel/acpi/sleep.h          |    2 +
 arch/x86/kernel/tboot.c               |   14 +-
 arch/x86/kernel/x86_init.c            |    1 +
 arch/x86/pci/xen.c                    |   29 +++
 arch/x86/xen/enlighten.c              |    3 +
 drivers/acpi/acpica/hwsleep.c         |   12 +-
 drivers/acpi/sleep.c                  |    2 +
 drivers/pci/msi.c                     |   29 +++-
 drivers/xen/Makefile                  |    2 +-
 drivers/xen/acpi.c                    |   65 +++++++
 include/linux/tboot.h                 |    3 +-
 include/xen/acpi.h                    |   70 +++++++
 include/xen/interface/physdev.h       |   15 ++
 include/xen/interface/platform.h      |  320 +++++++++++++++++++++++++++++++++
 include/xen/interface/xen.h           |    1 +
 23 files changed, 591 insertions(+), 13 deletions(-)

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