Merge branches 'for-next/kpti', 'for-next/missing-proto-warn',...

	arm64.nosme	[ARM64] Unconditionally disable Scalable Matrix

			Extension support

	arm64.nomops	[ARM64] Unconditionally disable Memory Copy and Memory

			Set instructions support

	ataflop=	[HW,M68k]

	atarimouse=	[HW,MOUSE] Atari Mouse

       -  Recommended: BERT, EINJ, ERST, HEST, PCCT, SSDT

       -  Optional: BGRT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT, IBFT,

          IORT, MCHI, MPST, MSCT, NFIT, PMTT, RASF, SBST, SLIT, SPMI, SRAT,

          STAO, TCPA, TPM2, UEFI, XENV

       -  Optional: AGDI, BGRT, CEDT, CPEP, CSRT, DBG2, DRTM, ECDT, FACS, FPDT,

          HMAT, IBFT, IORT, MCHI, MPAM, MPST, MSCT, NFIT, PMTT, PPTT, RASF, SBST,

          SDEI, SLIT, SPMI, SRAT, STAO, TCPA, TPM2, UEFI, XENV

       -  Not supported: BOOT, DBGP, DMAR, ETDT, HPET, IVRS, LPIT, MSDM, OEMx,

          PSDT, RSDT, SLIC, WAET, WDAT, WDRT, WPBT

       -  Not supported: AEST, APMT, BOOT, DBGP, DMAR, ETDT, HPET, IVRS, LPIT,

          MSDM, OEMx, PDTT, PSDT, RAS2, RSDT, SLIC, WAET, WDAT, WDRT, WPBT

====== ========================================================================

Table  Usage for ARMv8 Linux

====== ========================================================================

AEST   Signature Reserved (signature == "AEST")

       **Arm Error Source Table**

       This table informs the OS of any error nodes in the system that are

       compliant with the Arm RAS architecture.

AGDI   Signature Reserved (signature == "AGDI")

       **Arm Generic diagnostic Dump and Reset Device Interface Table**

       This table describes a non-maskable event, that is used by the platform

       firmware, to request the OS to generate a diagnostic dump and reset the device.

APMT   Signature Reserved (signature == "APMT")

       **Arm Performance Monitoring Table**

       This table describes the properties of PMU support implmented by

       components in the system.

BERT   Section 18.3 (signature == "BERT")

       **Boot Error Record Table**

       Optional, not currently supported, with no real use-case for an

       ARM server.

CEDT   Signature Reserved (signature == "CEDT")

       **CXL Early Discovery Table**

       This table allows the OS to discover any CXL Host Bridges and the Host

       Bridge registers.

CPEP   Section 5.2.18 (signature == "CPEP")

       **Corrected Platform Error Polling table**

       Must be supplied if RAS support is provided by the platform.  It

       is recommended this table be supplied.

HMAT   Section 5.2.28 (signature == "HMAT")

       **Heterogeneous Memory Attribute Table**

       This table describes the memory attributes, such as memory side cache

       attributes and bandwidth and latency details, related to Memory Proximity

       Domains. The OS uses this information to optimize the system memory

       configuration.

HPET   Signature Reserved (signature == "HPET")

       **High Precision Event timer Table**

       Optional, not currently supported.

MPAM   Signature Reserved (signature == "MPAM")

       **Memory Partitioning And Monitoring table**

       This table allows the OS to discover the MPAM controls implemented by

       the subsystems.

MPST   Section 5.2.21 (signature == "MPST")

       **Memory Power State Table**

       Recommend for use on arm64; use of PCC is recommended when using CPPC

       to control performance and power for platform processors.

PDTT   Section 5.2.29 (signature == "PDTT")

       **Platform Debug Trigger Table**

       This table describes PCC channels used to gather debug logs of

       non-architectural features.

PMTT   Section 5.2.21.12 (signature == "PMTT")

       **Platform Memory Topology Table**

       Optional, not currently supported.

PPTT   Section 5.2.30 (signature == "PPTT")

       **Processor Properties Topology Table**

       This table provides the processor and cache topology.

PSDT   Section 5.2.11.3 (signature == "PSDT")

       **Persistent System Description Table**

       Obsolete table, will not be supported.

RAS2   Section 5.2.21 (signature == "RAS2")

       **RAS Features 2 table**

       This table provides interfaces for the RAS capabilities implemented in

       the platform.

RASF   Section 5.2.20 (signature == "RASF")

       **RAS Feature table**

       Optional, not currently supported.

SDEI   Signature Reserved (signature == "SDEI")

       **Software Delegated Exception Interface table**

       This table advertises the presence of the SDEI interface.

SLIC   Signature Reserved (signature == "SLIC")

       **Software LIcensing table**

=====================

ACPI on ARMv8 Servers

=====================

ACPI can be used for ARMv8 general purpose servers designed to follow

the ARM SBSA (Server Base System Architecture) [0] and SBBR (Server

Base Boot Requirements) [1] specifications.  Please note that the SBBR

can be retrieved simply by visiting [1], but the SBSA is currently only

available to those with an ARM login due to ARM IP licensing concerns.

The ARMv8 kernel implements the reduced hardware model of ACPI version

===================

ACPI on Arm systems

===================

ACPI can be used for Armv8 and Armv9 systems designed to follow

the BSA (Arm Base System Architecture) [0] and BBR (Arm

Base Boot Requirements) [1] specifications.  Both BSA and BBR are publicly

accessible documents.

Arm Servers, in addition to being BSA compliant, comply with a set

of rules defined in SBSA (Server Base System Architecture) [2].

The Arm kernel implements the reduced hardware model of ACPI version

5.1 or later.  Links to the specification and all external documents

it refers to are managed by the UEFI Forum.  The specification is

available at http://www.uefi.org/specifications and documents referenced

by the specification can be found via http://www.uefi.org/acpi.

If an ARMv8 system does not meet the requirements of the SBSA and SBBR,

If an Arm system does not meet the requirements of the BSA and BBR,

or cannot be described using the mechanisms defined in the required ACPI

specifications, then ACPI may not be a good fit for the hardware.

While the documents mentioned above set out the requirements for building

industry-standard ARMv8 servers, they also apply to more than one operating

industry-standard Arm systems, they also apply to more than one operating

system.  The purpose of this document is to describe the interaction between

ACPI and Linux only, on an ARMv8 system -- that is, what Linux expects of

ACPI and Linux only, on an Arm system -- that is, what Linux expects of

ACPI and what ACPI can expect of Linux.

Why ACPI on ARM?

Why ACPI on Arm?

----------------

Before examining the details of the interface between ACPI and Linux, it is

useful to understand why ACPI is being used.  Several technologies already

exist in Linux for describing non-enumerable hardware, after all.  In this

section we summarize a blog post [2] from Grant Likely that outlines the

reasoning behind ACPI on ARMv8 servers.  Actually, we snitch a good portion

section we summarize a blog post [3] from Grant Likely that outlines the

reasoning behind ACPI on Arm systems.  Actually, we snitch a good portion

of the summary text almost directly, to be honest.

The short form of the rationale for ACPI on ARM is:

The short form of the rationale for ACPI on Arm is:

-  ACPI’s byte code (AML) allows the platform to encode hardware behavior,

   while DT explicitly does not support this.  For hardware vendors, being

-  In the enterprise server environment, ACPI has established bindings (such

   as for RAS) which are currently used in production systems.  DT does not.

   Such bindings could be defined in DT at some point, but doing so means ARM

   Such bindings could be defined in DT at some point, but doing so means Arm

   and x86 would end up using completely different code paths in both firmware

   and the kernel.

Relationship with Device Tree

-----------------------------

ACPI support in drivers and subsystems for ARMv8 should never be mutually

ACPI support in drivers and subsystems for Arm should never be mutually

exclusive with DT support at compile time.

At boot time the kernel will only use one description method depending on

Booting using ACPI tables

-------------------------

The only defined method for passing ACPI tables to the kernel on ARMv8

The only defined method for passing ACPI tables to the kernel on Arm

is via the UEFI system configuration table.  Just so it is explicit, this

means that ACPI is only supported on platforms that boot via UEFI.

When an ARMv8 system boots, it can either have DT information, ACPI tables,

When an Arm system boots, it can either have DT information, ACPI tables,

or in some very unusual cases, both.  If no command line parameters are used,

the kernel will try to use DT for device enumeration; if there is no DT

present, the kernel will try to use ACPI tables, but only if they are present.

For the ACPI core to operate properly, and in turn provide the information

the kernel needs to configure devices, it expects to find the following

tables (all section numbers refer to the ACPI 6.1 specification):

tables (all section numbers refer to the ACPI 6.5 specification):

    -  RSDP (Root System Description Pointer), section 5.2.5

    -  GTDT (Generic Timer Description Table), section 5.2.24

    -  PPTT (Processor Properties Topology Table), section 5.2.30

    -  DBG2 (DeBuG port table 2), section 5.2.6, specifically Table 5-6.

    -  APMT (Arm Performance Monitoring unit Table), section 5.2.6, specifically Table 5-6.

    -  AGDI (Arm Generic diagnostic Dump and Reset Device Interface Table), section 5.2.6, specifically Table 5-6.

    -  If PCI is supported, the MCFG (Memory mapped ConFiGuration

       Table), section 5.2.6, specifically Table 5-31.

       Table), section 5.2.6, specifically Table 5-6.

    -  If booting without a console=<device> kernel parameter is

       supported, the SPCR (Serial Port Console Redirection table),

       section 5.2.6, specifically Table 5-31.

       section 5.2.6, specifically Table 5-6.

    -  If necessary to describe the I/O topology, SMMUs and GIC ITSs,

       the IORT (Input Output Remapping Table, section 5.2.6, specifically

       Table 5-31).

       Table 5-6).

    -  If NUMA is supported, the following tables are required:

       - SRAT (System Resource Affinity Table), section 5.2.16

       - SLIT (System Locality distance Information Table), section 5.2.17

    -  If NUMA is supported, and the system contains heterogeneous memory,

       the HMAT (Heterogeneous Memory Attribute Table), section 5.2.28.

    -  If the ACPI Platform Error Interfaces are required, the following

       tables are conditionally required:

       - BERT (Boot Error Record Table, section 18.3.1)

       - EINJ (Error INJection table, section 18.6.1)

       - ERST (Error Record Serialization Table, section 18.5)

       - HEST (Hardware Error Source Table, section 18.3.2)

       - SDEI (Software Delegated Exception Interface table, section 5.2.6,

         specifically Table 5-6)

       - AEST (Arm Error Source Table, section 5.2.6,

         specifically Table 5-6)

       - RAS2 (ACPI RAS2 feature table, section 5.2.21)

    -  If the system contains controllers using PCC channel, the

       PCCT (Platform Communications Channel Table), section 14.1

    -  If the system contains a controller to capture board-level system state,

       and communicates with the host via PCC, the PDTT (Platform Debug Trigger

       Table), section 5.2.29.

    -  If NVDIMM is supported, the NFIT (NVDIMM Firmware Interface Table), section 5.2.26

    -  If video framebuffer is present, the BGRT (Boot Graphics Resource Table), section 5.2.23

    -  If IPMI is implemented, the SPMI (Server Platform Management Interface),

       section 5.2.6, specifically Table 5-6.

    -  If the system contains a CXL Host Bridge, the CEDT (CXL Early Discovery

       Table), section 5.2.6, specifically Table 5-6.

    -  If the system supports MPAM, the MPAM (Memory Partitioning And Monitoring table), section 5.2.6,

       specifically Table 5-6.

    -  If the system lacks persistent storage, the IBFT (ISCSI Boot Firmware

       Table), section 5.2.6, specifically Table 5-6.

    -  If NUMA is supported, the SRAT (System Resource Affinity Table)

       and SLIT (System Locality distance Information Table), sections

       5.2.16 and 5.2.17, respectively.

If the above tables are not all present, the kernel may or may not be

able to boot properly since it may not be able to configure all of the

object is described in the ACPI specification section 6.2.5, but this only

describes how to define the structure of an object returned via _DSD, and

how specific data structures are defined by specific UUIDs.  Linux should

only use the _DSD Device Properties UUID [5]:

only use the _DSD Device Properties UUID [4]:

   - UUID: daffd814-6eba-4d8c-8a91-bc9bbf4aa301

   - https://www.uefi.org/sites/default/files/resources/_DSD-device-properties-UUID.pdf

The UEFI Forum provides a mechanism for registering device properties [4]

so that they may be used across all operating systems supporting ACPI.

Device properties that have not been registered with the UEFI Forum should

not be used.

Common device properties can be registered by creating a pull request to [4] so

that they may be used across all operating systems supporting ACPI.

Device properties that have not been registered with the UEFI Forum can be used

but not as "uefi-" common properties.

Before creating new device properties, check to be sure that they have not

been defined before and either registered in the Linux kernel documentation

Once registration and review have been completed, the kernel provides an

interface for looking up device properties in a manner independent of

whether DT or ACPI is being used.  This API should be used [6]; it can

whether DT or ACPI is being used.  This API should be used [5]; it can

eliminate some duplication of code paths in driver probing functions and

discourage divergence between DT bindings and ACPI device properties.

----

The ACPI specification changes regularly.  During the year 2014, for instance,

version 5.1 was released and version 6.0 substantially completed, with most of

the changes being driven by ARM-specific requirements.  Proposed changes are

the changes being driven by Arm-specific requirements.  Proposed changes are

presented and discussed in the ASWG (ACPI Specification Working Group) which

is a part of the UEFI Forum.  The current version of the ACPI specification

is 6.1 release in January 2016.

is 6.5 release in August 2022.

Participation in this group is open to all UEFI members.  Please see

http://www.uefi.org/workinggroup for details on group membership.

It is the intent of the ARMv8 ACPI kernel code to follow the ACPI specification

It is the intent of the Arm ACPI kernel code to follow the ACPI specification

as closely as possible, and to only implement functionality that complies with

the released standards from UEFI ASWG.  As a practical matter, there will be

vendors that provide bad ACPI tables or violate the standards in some way.

Linux Code

----------

Individual items specific to Linux on ARM, contained in the Linux

Individual items specific to Linux on Arm, contained in the Linux

source code, are in the list that follows:

ACPI_OS_NAME

                       This macro defines the string to be returned when

                       an ACPI method invokes the _OS method.  On ARM64

                       an ACPI method invokes the _OS method.  On Arm

                       systems, this macro will be "Linux" by default.

                       The command line parameter acpi_os=<string>

                       can be used to set it to some other value.  The

References

----------

[0] http://silver.arm.com

    document ARM-DEN-0029, or newer:

    "Server Base System Architecture", version 2.3, dated 27 Mar 2014

[0] https://developer.arm.com/documentation/den0094/latest

    document Arm-DEN-0094: "Arm Base System Architecture", version 1.0C, dated 6 Oct 2022

[1] https://developer.arm.com/documentation/den0044/latest

    Document Arm-DEN-0044: "Arm Base Boot Requirements", version 2.0G, dated 15 Apr 2022

[1] http://infocenter.arm.com/help/topic/com.arm.doc.den0044a/Server_Base_Boot_Requirements.pdf

    Document ARM-DEN-0044A, or newer: "Server Base Boot Requirements, System

    Software on ARM Platforms", dated 16 Aug 2014

[2] https://developer.arm.com/documentation/den0029/latest

    Document Arm-DEN-0029: "Arm Server Base System Architecture", version 7.1, dated 06 Oct 2022

[2] http://www.secretlab.ca/archives/151,

[3] http://www.secretlab.ca/archives/151,

    10 Jan 2015, Copyright (c) 2015,

    Linaro Ltd., written by Grant Likely.

[3] AMD ACPI for Seattle platform documentation

    http://amd-dev.wpengine.netdna-cdn.com/wordpress/media/2012/10/Seattle_ACPI_Guide.pdf

[4] http://www.uefi.org/acpi

    please see the link for the "ACPI _DSD Device

    Property Registry Instructions"

[5] http://www.uefi.org/acpi

    please see the link for the "_DSD (Device

    Specific Data) Implementation Guide"

[4] _DSD (Device Specific Data) Implementation Guide

    https://github.com/UEFI/DSD-Guide/blob/main/dsd-guide.pdf

[6] Kernel code for the unified device

[5] Kernel code for the unified device

    property interface can be found in

    include/linux/property.h and drivers/base/property.c.

    - SMCR_EL2.EZT0 (bit 30) must be initialised to 0b1.

  For CPUs with Memory Copy and Memory Set instructions (FEAT_MOPS):

  - If the kernel is entered at EL1 and EL2 is present:

    - HCRX_EL2.MSCEn (bit 11) must be initialised to 0b1.

The requirements described above for CPU mode, caches, MMUs, architected

timers, coherency and system registers apply to all CPUs.  All CPUs must

enter the kernel in the same exception level.  Where the values documented

     +------------------------------+---------+---------+

     | Name                         |  bits   | visible |

     +------------------------------+---------+---------+

     | MOPS                         | [19-16] |    y    |

     +------------------------------+---------+---------+

     | RPRES                        | [7-4]   |    y    |

     +------------------------------+---------+---------+

     | WFXT                         | [3-0]   |    y    |