Pull ACPI updates from Rafael Wysocki:
 "These eliminate significant AML processing overhead related to using
  operation regions in system memory, update the ACPICA code in the
  kernel to upstream revision 20200717 (including a fix to prevent
  operation region reference counts from overflowing in some cases),
  remove the last bits of the (long deprecated) ACPI procfs interface
  and do some assorted cleanups.

  Specifics:

   - Eliminate significant AML processing overhead related to using
     operation regions in system memory by reworking the management of
     memory mappings in the ACPI code to defer unmap operations (to do
     them outside of the ACPICA locks, among other things) and making
     the memory operation reagion handler avoid releasing memory
     mappings created by it too early (Rafael Wysocki).

   - Update the ACPICA code in the kernel to upstream revision 20200717:

       * Prevent operation region reference counts from overflowing in
         some cases (Erik Kaneda).

       * Replace one-element array with flexible-array (Gustavo A. R.
         Silva).

   - Fix ACPI PCI hotplug reference counting (Rafael Wysocki).

   - Drop last bits of the ACPI procfs interface (Thomas Renninger).

   - Drop some redundant checks from the code parsing ACPI tables
     related to NUMA (Hanjun Guo).

   - Avoid redundant object evaluation in the ACPI device properties
     handling code (Heikki Krogerus).

   - Avoid unecessary memory overhead related to storing the signatures
     of the ACPI tables recognized by the kernel (Ard Biesheuvel).

   - Add missing newline characters when printing module parameter
     values in some places (Xiongfeng Wang).

   - Update the link to the ACPI specifications in some places (Tiezhu
     Yang).

   - Use the fallthrough pseudo-keyword in the ACPI code (Gustavo A. R.
     Silva).

   - Drop redundant variable initialization from the APEI code (Colin
     Ian King).

   - Drop uninitialized_var() from the ACPI PAD driver (Jason Yan).

   - Replace HTTP links with HTTPS ones in the ACPI code (Alexander A.
     Klimov)"

* tag 'acpi-5.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: (22 commits)
  ACPI: APEI: remove redundant assignment to variable rc
  ACPI: NUMA: Remove the useless 'node >= MAX_NUMNODES' check
  ACPI: NUMA: Remove the useless sub table pointer check
  ACPI: tables: Remove the duplicated checks for acpi_parse_entries_array()
  ACPICA: Update version to 20200717
  ACPICA: Do not increment operation_region reference counts for field units
  ACPICA: Replace one-element array with flexible-array
  ACPI: Replace HTTP links with HTTPS ones
  ACPI: Use valid link to the ACPI specification
  ACPI: OSL: Clean up the removal of unused memory mappings
  ACPI: OSL: Use deferred unmapping in acpi_os_unmap_iomem()
  ACPI: OSL: Use deferred unmapping in acpi_os_unmap_generic_address()
  ACPICA: Preserve memory opregion mappings
  ACPI: OSL: Implement deferred unmapping of ACPI memory
  ACPI: Use fallthrough pseudo-keyword
  PCI: hotplug: ACPI: Fix context refcounting in acpiphp_grab_context()
  ACPI: tables: avoid relocations for table signature array
  ACPI: PAD: Eliminate usage of uninitialized_var() macro
  ACPI: sysfs: add newlines when printing module parameters
  ACPI: EC: add newline when printing 'ec_event_clearing' module parameter
  ...

Add return value to fix return-type build warning introduced by
commit efe9711214e6 ("cpuidle: change enter_s2idle() prototype").

Fixes: efe9711214e6 ("cpuidle: change enter_s2idle() prototype")
Signed-off-by: Neal Liu <neal.liu@mediatek.com>
[ rjw: Subject & changelog edits, make acpi_idle_enter_s2idle()
  return 0 in all cases ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Control Flow Integrity(CFI) is a security mechanism that disallows
changes to the original control flow graph of a compiled binary,
making it significantly harder to perform such attacks.

init_state_node() assign same function callback to different
function pointer declarations.

static int init_state_node(struct cpuidle_state *idle_state,
                           const struct of_device_id *matches,
                           struct device_node *state_node) { ...
        idle_state->enter = match_id->data; ...
        idle_state->enter_s2idle = match_id->data; }

Function declarations:

struct cpuidle_state { ...
        int (*enter) (struct cpuidle_device *dev,
                      struct cpuidle_driver *drv,
                      int index);

        void (*enter_s2idle) (struct cpuidle_device *dev,
                              struct cpuidle_driver *drv,
                              int index); };

In this case, either enter() or enter_s2idle() would cause CFI check
failed since they use same callee.

Align function prototype of enter() since it needs return value for
some use cases. The return value of enter_s2idle() is no
need currently.

Signed-off-by: Neal Liu <neal.liu@mediatek.com>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through # [1]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

It is possible for ACPI _CST to return only one ACPI C-state, for
example, when deep cstate disabled in the BIOS.

And it is better for the acpi_idle driver to probe succesfully in
this case as well for consistency.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The intel_idle driver will be modified to use ACPI _CST subsequently
and it will need to call acpi_processor_evaluate_cst(), so move that
function to acpi_processor.c so that it is always present (which is
required by intel_idle) and export it to modules to allow the ACPI
processor driver (which is modular) to call it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

Clean up acpi_processor_evaluate_cst() in multiple ways:

 * Rename current_count to last_index which matches the purpose of
   the variable better.

 * Consistently use acpi_handle_*() for printing messages and make
   the messages cleaner.

 * Drop redundant parens and braces.

 * Rewrite and clarify comments.

 * Rearrange checks and drop the redundant ones.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

In order to separate the ACPI _CST evaluation from checks
specific to the ACPI processor driver, move the majority of
the acpi_processor_get_power_info_cst() function body to a new
function, acpi_processor_evaluate_cst(), that will extract
the C-states information from _CST output, and redefine
acpi_processor_get_power_info_cst() as a wrapper around it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

The intel_idle driver will be modified to use ACPI _CST subsequently
and it will need to notify the platform firmware of that if
acpi_gbl_FADT.cst_control is set, so add a routine for this purpose,
acpi_processor_claim_cst_control(), to acpi_processor.c (so that it
is always present which is required by intel_idle) and export it
to allow the ACPI processor driver (which is modular) to call it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

In function acpi_idle_do_entry(), an ioport access is used for
dummy wait to guarantee hardware behavior. But it could trigger
unnecessary VMexit if kernel is running as guest in virtualization
environment.

If it's in virtualization environment, the deeper C state enter
operation (inb()) will trap to hypervisor. It's not needed to do
dummy wait after the inb() call. So we could just remove the
dummy io port access to avoid unnecessary VMexit.

And keep dummy io port access to maintain timing for native
environment.

Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>