linux/drivers/platform
Linus Torvalds ca7e917769 Rework of APIC enumeration and topology evaluation:
The current implementation has a couple of shortcomings:
 
   - It fails to handle hybrid systems correctly.
 
   - The APIC registration code which handles CPU number assignents is in
     the middle of the APIC code and detached from the topology evaluation.
 
   - The various mechanisms which enumerate APICs, ACPI, MPPARSE and guest
     specific ones, tweak global variables as they see fit or in case of
     XENPV just hack around the generic mechanisms completely.
 
   - The CPUID topology evaluation code is sprinkled all over the vendor
     code and reevaluates global variables on every hotplug operation.
 
   - There is no way to analyze topology on the boot CPU before bringing up
     the APs. This causes problems for infrastructure like PERF which needs
     to size certain aspects upfront or could be simplified if that would be
     possible.
 
   - The APIC admission and CPU number association logic is incomprehensible
     and overly complex and needs to be kept around after boot instead of
     completing this right after the APIC enumeration.
 
 This update addresses these shortcomings with the following changes:
 
   - Rework the CPUID evaluation code so it is common for all vendors and
     provides information about the APIC ID segments in a uniform way
     independent of the number of segments (Thread, Core, Module, ..., Die,
     Package) so that this information can be computed instead of rewriting
     global variables of dubious value over and over.
 
   - A few cleanups and simplifcations of the APIC, IO/APIC and related
     interfaces to prepare for the topology evaluation changes.
 
   - Seperation of the parser stages so the early evaluation which tries to
     find the APIC address can be seperately overridden from the late
     evaluation which enumerates and registers the local APIC as further
     preparation for sanitizing the topology evaluation.
 
   - A new registration and admission logic which
 
      - encapsulates the inner workings so that parsers and guest logic
        cannot longer fiddle in it
 
      - uses the APIC ID segments to build topology bitmaps at registration
        time
 
      - provides a sane admission logic
 
      - allows to detect the crash kernel case, where CPU0 does not run on
        the real BSP, automatically. This is required to prevent sending
        INIT/SIPI sequences to the real BSP which would reset the whole
        machine. This was so far handled by a tedious command line
        parameter, which does not even work in nested crash scenarios.
 
      - Associates CPU number after the enumeration completed and prevents
        the late registration of APICs, which was somehow tolerated before.
 
   - Converting all parsers and guest enumeration mechanisms over to the
     new interfaces.
 
     This allows to get rid of all global variable tweaking from the parsers
     and enumeration mechanisms and sanitizes the XEN[PV] handling so it can
     use CPUID evaluation for the first time.
 
   - Mopping up existing sins by taking the information from the APIC ID
     segment bitmaps.
 
     This evaluates hybrid systems correctly on the boot CPU and allows for
     cleanups and fixes in the related drivers, e.g. PERF.
 
 The series has been extensively tested and the minimal late fallout due to
 a broken ACPI/MADT table has been addressed by tightening the admission
 logic further.
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Merge tag 'x86-apic-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 APIC updates from Thomas Gleixner:
 "Rework of APIC enumeration and topology evaluation.

  The current implementation has a couple of shortcomings:

   - It fails to handle hybrid systems correctly.

   - The APIC registration code which handles CPU number assignents is
     in the middle of the APIC code and detached from the topology
     evaluation.

   - The various mechanisms which enumerate APICs, ACPI, MPPARSE and
     guest specific ones, tweak global variables as they see fit or in
     case of XENPV just hack around the generic mechanisms completely.

   - The CPUID topology evaluation code is sprinkled all over the vendor
     code and reevaluates global variables on every hotplug operation.

   - There is no way to analyze topology on the boot CPU before bringing
     up the APs. This causes problems for infrastructure like PERF which
     needs to size certain aspects upfront or could be simplified if
     that would be possible.

   - The APIC admission and CPU number association logic is
     incomprehensible and overly complex and needs to be kept around
     after boot instead of completing this right after the APIC
     enumeration.

  This update addresses these shortcomings with the following changes:

   - Rework the CPUID evaluation code so it is common for all vendors
     and provides information about the APIC ID segments in a uniform
     way independent of the number of segments (Thread, Core, Module,
     ..., Die, Package) so that this information can be computed instead
     of rewriting global variables of dubious value over and over.

   - A few cleanups and simplifcations of the APIC, IO/APIC and related
     interfaces to prepare for the topology evaluation changes.

   - Seperation of the parser stages so the early evaluation which tries
     to find the APIC address can be seperately overridden from the late
     evaluation which enumerates and registers the local APIC as further
     preparation for sanitizing the topology evaluation.

   - A new registration and admission logic which

       - encapsulates the inner workings so that parsers and guest logic
         cannot longer fiddle in it

       - uses the APIC ID segments to build topology bitmaps at
         registration time

       - provides a sane admission logic

       - allows to detect the crash kernel case, where CPU0 does not run
         on the real BSP, automatically. This is required to prevent
         sending INIT/SIPI sequences to the real BSP which would reset
         the whole machine. This was so far handled by a tedious command
         line parameter, which does not even work in nested crash
         scenarios.

       - Associates CPU number after the enumeration completed and
         prevents the late registration of APICs, which was somehow
         tolerated before.

   - Converting all parsers and guest enumeration mechanisms over to the
     new interfaces.

     This allows to get rid of all global variable tweaking from the
     parsers and enumeration mechanisms and sanitizes the XEN[PV]
     handling so it can use CPUID evaluation for the first time.

   - Mopping up existing sins by taking the information from the APIC ID
     segment bitmaps.

     This evaluates hybrid systems correctly on the boot CPU and allows
     for cleanups and fixes in the related drivers, e.g. PERF.

  The series has been extensively tested and the minimal late fallout
  due to a broken ACPI/MADT table has been addressed by tightening the
  admission logic further"

* tag 'x86-apic-2024-03-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (76 commits)
  x86/topology: Ignore non-present APIC IDs in a present package
  x86/apic: Build the x86 topology enumeration functions on UP APIC builds too
  smp: Provide 'setup_max_cpus' definition on UP too
  smp: Avoid 'setup_max_cpus' namespace collision/shadowing
  x86/bugs: Use fixed addressing for VERW operand
  x86/cpu/topology: Get rid of cpuinfo::x86_max_cores
  x86/cpu/topology: Provide __num_[cores|threads]_per_package
  x86/cpu/topology: Rename topology_max_die_per_package()
  x86/cpu/topology: Rename smp_num_siblings
  x86/cpu/topology: Retrieve cores per package from topology bitmaps
  x86/cpu/topology: Use topology logical mapping mechanism
  x86/cpu/topology: Provide logical pkg/die mapping
  x86/cpu/topology: Simplify cpu_mark_primary_thread()
  x86/cpu/topology: Mop up primary thread mask handling
  x86/cpu/topology: Use topology bitmaps for sizing
  x86/cpu/topology: Let XEN/PV use topology from CPUID/MADT
  x86/xen/smp_pv: Count number of vCPUs early
  x86/cpu/topology: Assign hotpluggable CPUIDs during init
  x86/cpu/topology: Reject unknown APIC IDs on ACPI hotplug
  x86/topology: Add a mechanism to track topology via APIC IDs
  ...
2024-03-11 15:45:55 -07:00
..
chrome TTY/Serial changes for 6.8-rc1 2024-01-18 11:37:24 -08:00
goldfish platform/goldfish: goldfish_pipe: Convert to platform remove callback returning void 2023-11-28 19:03:24 +00:00
loongarch platform/loongarch: laptop: Fix possible UAF and simplify generic_acpi_laptop_init() 2022-10-29 16:29:31 +08:00
mellanox platform/mellanox: mlxbf-pmc: Fix offset calculation for crspace events 2024-01-22 12:22:27 +01:00
mips mips: rs870e: stop exporting local functions 2023-12-10 17:21:39 -08:00
olpc platform/olpc: olpc-xo175-ec: Use SPI device ID data to bind device 2023-03-20 14:43:35 +01:00
surface TTY/Serial changes for 6.8-rc1 2024-01-18 11:37:24 -08:00
x86 Rework of APIC enumeration and topology evaluation: 2024-03-11 15:45:55 -07:00
Kconfig platform/mips: Adjust Kconfig to keep consistency 2022-12-08 11:51:52 +01:00
Makefile LoongArch: Add ACPI-based generic laptop driver 2022-10-12 16:36:20 +08:00