linux/Documentation/arch/x86
Linus Torvalds eb55307e67 X86 core code updates:
- Limit the hardcoded topology quirk for Hygon CPUs to those which have a
     model ID less than 4. The newer models have the topology CPUID leaf 0xB
     correctly implemented and are not affected.
 
   - Make SMT control more robust against enumeration failures
 
     SMT control was added to allow controlling SMT at boottime or
     runtime. The primary purpose was to provide a simple mechanism to
     disable SMT in the light of speculation attack vectors.
 
     It turned out that the code is sensible to enumeration failures and
     worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
     which means the primary thread mask is not set up correctly. By chance
     a XEN/PV boot ends up with smp_num_siblings == 2, which makes the
     hotplug control stay at its default value "enabled". So the mask is
     never evaluated.
 
     The ongoing rework of the topology evaluation caused XEN/PV to end up
     with smp_num_siblings == 1, which sets the SMT control to "not
     supported" and the empty primary thread mask causes the hotplug core to
     deny the bringup of the APS.
 
     Make the decision logic more robust and take 'not supported' and 'not
     implemented' into account for the decision whether a CPU should be
     booted or not.
 
   - Fake primary thread mask for XEN/PV
 
     Pretend that all XEN/PV vCPUs are primary threads, which makes the
     usage of the primary thread mask valid on XEN/PV. That is consistent
     with because all of the topology information on XEN/PV is fake or even
     non-existent.
 
   - Encapsulate topology information in cpuinfo_x86
 
     Move the randomly scattered topology data into a separate data
     structure for readability and as a preparatory step for the topology
     evaluation overhaul.
 
   - Consolidate APIC ID data type to u32
 
     It's fixed width hardware data and not randomly u16, int, unsigned long
     or whatever developers decided to use.
 
   - Cure the abuse of cpuinfo for persisting logical IDs.
 
     Per CPU cpuinfo is used to persist the logical package and die
     IDs. That's really not the right place simply because cpuinfo is
     subject to be reinitialized when a CPU goes through an offline/online
     cycle.
 
     Use separate per CPU data for the persisting to enable the further
     topology management rework. It will be removed once the new topology
     management is in place.
 
   - Provide a debug interface for inspecting topology information
 
     Useful in general and extremly helpful for validating the topology
     management rework in terms of correctness or "bug" compatibility.
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Merge tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 core updates from Thomas Gleixner:

 - Limit the hardcoded topology quirk for Hygon CPUs to those which have
   a model ID less than 4.

   The newer models have the topology CPUID leaf 0xB correctly
   implemented and are not affected.

 - Make SMT control more robust against enumeration failures

   SMT control was added to allow controlling SMT at boottime or
   runtime. The primary purpose was to provide a simple mechanism to
   disable SMT in the light of speculation attack vectors.

   It turned out that the code is sensible to enumeration failures and
   worked only by chance for XEN/PV. XEN/PV has no real APIC enumeration
   which means the primary thread mask is not set up correctly. By
   chance a XEN/PV boot ends up with smp_num_siblings == 2, which makes
   the hotplug control stay at its default value "enabled". So the mask
   is never evaluated.

   The ongoing rework of the topology evaluation caused XEN/PV to end up
   with smp_num_siblings == 1, which sets the SMT control to "not
   supported" and the empty primary thread mask causes the hotplug core
   to deny the bringup of the APS.

   Make the decision logic more robust and take 'not supported' and 'not
   implemented' into account for the decision whether a CPU should be
   booted or not.

 - Fake primary thread mask for XEN/PV

   Pretend that all XEN/PV vCPUs are primary threads, which makes the
   usage of the primary thread mask valid on XEN/PV. That is consistent
   with because all of the topology information on XEN/PV is fake or
   even non-existent.

 - Encapsulate topology information in cpuinfo_x86

   Move the randomly scattered topology data into a separate data
   structure for readability and as a preparatory step for the topology
   evaluation overhaul.

 - Consolidate APIC ID data type to u32

   It's fixed width hardware data and not randomly u16, int, unsigned
   long or whatever developers decided to use.

 - Cure the abuse of cpuinfo for persisting logical IDs.

   Per CPU cpuinfo is used to persist the logical package and die IDs.
   That's really not the right place simply because cpuinfo is subject
   to be reinitialized when a CPU goes through an offline/online cycle.

   Use separate per CPU data for the persisting to enable the further
   topology management rework. It will be removed once the new topology
   management is in place.

 - Provide a debug interface for inspecting topology information

   Useful in general and extremly helpful for validating the topology
   management rework in terms of correctness or "bug" compatibility.

* tag 'x86-core-2023-10-29-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  x86/apic, x86/hyperv: Use u32 in hv_snp_boot_ap() too
  x86/cpu: Provide debug interface
  x86/cpu/topology: Cure the abuse of cpuinfo for persisting logical ids
  x86/apic: Use u32 for wakeup_secondary_cpu[_64]()
  x86/apic: Use u32 for [gs]et_apic_id()
  x86/apic: Use u32 for phys_pkg_id()
  x86/apic: Use u32 for cpu_present_to_apicid()
  x86/apic: Use u32 for check_apicid_used()
  x86/apic: Use u32 for APIC IDs in global data
  x86/apic: Use BAD_APICID consistently
  x86/cpu: Move cpu_l[l2]c_id into topology info
  x86/cpu: Move logical package and die IDs into topology info
  x86/cpu: Remove pointless evaluation of x86_coreid_bits
  x86/cpu: Move cu_id into topology info
  x86/cpu: Move cpu_core_id into topology info
  hwmon: (fam15h_power) Use topology_core_id()
  scsi: lpfc: Use topology_core_id()
  x86/cpu: Move cpu_die_id into topology info
  x86/cpu: Move phys_proc_id into topology info
  x86/cpu: Encapsulate topology information in cpuinfo_x86
  ...
2023-10-30 17:37:47 -10:00
..
i386
x86_64
amd_hsmp.rst
amd-memory-encryption.rst x86/sev/docs: Update document URL in amd-memory-encryption.rst 2023-09-22 11:29:23 +02:00
boot.rst Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
booting-dt.rst
buslock.rst Documentation: Fix typos 2023-08-18 11:29:03 -06:00
cpuinfo.rst
earlyprintk.rst
elf_auxvec.rst
entry_64.rst
exception-tables.rst
features.rst
ifs.rst
index.rst Documentation/x86: Add CET shadow stack description 2023-08-02 15:01:50 -07:00
intel_txt.rst
intel-hfi.rst
iommu.rst x86/iommu/docs: Update AMD IOMMU specification document URL 2023-09-24 10:47:35 +02:00
kernel-stacks.rst
mds.rst Documentation: Fix typos 2023-08-18 11:29:03 -06:00
microcode.rst
mtrr.rst
orc-unwinder.rst
pat.rst
pti.rst
resctrl.rst x86/resctrl: Display RMID of resource group 2023-10-17 14:05:40 +02:00
sgx.rst Documentation: Fix typos 2023-08-18 11:29:03 -06:00
shstk.rst x86/shstk: Add ARCH_SHSTK_STATUS 2023-08-02 15:01:51 -07:00
sva.rst
tdx.rst
tlb.rst
topology.rst x86/cpu: Move cpu_l[l2]c_id into topology info 2023-10-10 14:38:18 +02:00
tsx_async_abort.rst
usb-legacy-support.rst
xstate.rst
zero-page.rst