Commit Graph

2664 Commits

Author SHA1 Message Date
Linus Torvalds
61307b7be4 Merge tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull mm updates from Andrew Morton:
 "The usual shower of singleton fixes and minor series all over MM,
  documented (hopefully adequately) in the respective changelogs.
  Notable series include:

   - Lucas Stach has provided some page-mapping cleanup/consolidation/
     maintainability work in the series "mm/treewide: Remove pXd_huge()
     API".

   - In the series "Allow migrate on protnone reference with
     MPOL_PREFERRED_MANY policy", Donet Tom has optimized mempolicy's
     MPOL_PREFERRED_MANY mode, yielding almost doubled performance in
     one test.

   - In their series "Memory allocation profiling" Kent Overstreet and
     Suren Baghdasaryan have contributed a means of determining (via
     /proc/allocinfo) whereabouts in the kernel memory is being
     allocated: number of calls and amount of memory.

   - Matthew Wilcox has provided the series "Various significant MM
     patches" which does a number of rather unrelated things, but in
     largely similar code sites.

   - In his series "mm: page_alloc: freelist migratetype hygiene"
     Johannes Weiner has fixed the page allocator's handling of
     migratetype requests, with resulting improvements in compaction
     efficiency.

   - In the series "make the hugetlb migration strategy consistent"
     Baolin Wang has fixed a hugetlb migration issue, which should
     improve hugetlb allocation reliability.

   - Liu Shixin has hit an I/O meltdown caused by readahead in a
     memory-tight memcg. Addressed in the series "Fix I/O high when
     memory almost met memcg limit".

   - In the series "mm/filemap: optimize folio adding and splitting"
     Kairui Song has optimized pagecache insertion, yielding ~10%
     performance improvement in one test.

   - Baoquan He has cleaned up and consolidated the early zone
     initialization code in the series "mm/mm_init.c: refactor
     free_area_init_core()".

   - Baoquan has also redone some MM initializatio code in the series
     "mm/init: minor clean up and improvement".

   - MM helper cleanups from Christoph Hellwig in his series "remove
     follow_pfn".

   - More cleanups from Matthew Wilcox in the series "Various
     page->flags cleanups".

   - Vlastimil Babka has contributed maintainability improvements in the
     series "memcg_kmem hooks refactoring".

   - More folio conversions and cleanups in Matthew Wilcox's series:
	"Convert huge_zero_page to huge_zero_folio"
	"khugepaged folio conversions"
	"Remove page_idle and page_young wrappers"
	"Use folio APIs in procfs"
	"Clean up __folio_put()"
	"Some cleanups for memory-failure"
	"Remove page_mapping()"
	"More folio compat code removal"

   - David Hildenbrand chipped in with "fs/proc/task_mmu: convert
     hugetlb functions to work on folis".

   - Code consolidation and cleanup work related to GUP's handling of
     hugetlbs in Peter Xu's series "mm/gup: Unify hugetlb, part 2".

   - Rick Edgecombe has developed some fixes to stack guard gaps in the
     series "Cover a guard gap corner case".

   - Jinjiang Tu has fixed KSM's behaviour after a fork+exec in the
     series "mm/ksm: fix ksm exec support for prctl".

   - Baolin Wang has implemented NUMA balancing for multi-size THPs.
     This is a simple first-cut implementation for now. The series is
     "support multi-size THP numa balancing".

   - Cleanups to vma handling helper functions from Matthew Wilcox in
     the series "Unify vma_address and vma_pgoff_address".

   - Some selftests maintenance work from Dev Jain in the series
     "selftests/mm: mremap_test: Optimizations and style fixes".

   - Improvements to the swapping of multi-size THPs from Ryan Roberts
     in the series "Swap-out mTHP without splitting".

   - Kefeng Wang has significantly optimized the handling of arm64's
     permission page faults in the series
	"arch/mm/fault: accelerate pagefault when badaccess"
	"mm: remove arch's private VM_FAULT_BADMAP/BADACCESS"

   - GUP cleanups from David Hildenbrand in "mm/gup: consistently call
     it GUP-fast".

   - hugetlb fault code cleanups from Vishal Moola in "Hugetlb fault
     path to use struct vm_fault".

   - selftests build fixes from John Hubbard in the series "Fix
     selftests/mm build without requiring "make headers"".

   - Memory tiering fixes/improvements from Ho-Ren (Jack) Chuang in the
     series "Improved Memory Tier Creation for CPUless NUMA Nodes".
     Fixes the initialization code so that migration between different
     memory types works as intended.

   - David Hildenbrand has improved follow_pte() and fixed an errant
     driver in the series "mm: follow_pte() improvements and acrn
     follow_pte() fixes".

   - David also did some cleanup work on large folio mapcounts in his
     series "mm: mapcount for large folios + page_mapcount() cleanups".

   - Folio conversions in KSM in Alex Shi's series "transfer page to
     folio in KSM".

   - Barry Song has added some sysfs stats for monitoring multi-size
     THP's in the series "mm: add per-order mTHP alloc and swpout
     counters".

   - Some zswap cleanups from Yosry Ahmed in the series "zswap
     same-filled and limit checking cleanups".

   - Matthew Wilcox has been looking at buffer_head code and found the
     documentation to be lacking. The series is "Improve buffer head
     documentation".

   - Multi-size THPs get more work, this time from Lance Yang. His
     series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free"
     optimizes the freeing of these things.

   - Kemeng Shi has added more userspace-visible writeback
     instrumentation in the series "Improve visibility of writeback".

   - Kemeng Shi then sent some maintenance work on top in the series
     "Fix and cleanups to page-writeback".

   - Matthew Wilcox reduces mmap_lock traffic in the anon vma code in
     the series "Improve anon_vma scalability for anon VMAs". Intel's
     test bot reported an improbable 3x improvement in one test.

   - SeongJae Park adds some DAMON feature work in the series
	"mm/damon: add a DAMOS filter type for page granularity access recheck"
	"selftests/damon: add DAMOS quota goal test"

   - Also some maintenance work in the series
	"mm/damon/paddr: simplify page level access re-check for pageout"
	"mm/damon: misc fixes and improvements"

   - David Hildenbrand has disabled some known-to-fail selftests ni the
     series "selftests: mm: cow: flag vmsplice() hugetlb tests as
     XFAIL".

   - memcg metadata storage optimizations from Shakeel Butt in "memcg:
     reduce memory consumption by memcg stats".

   - DAX fixes and maintenance work from Vishal Verma in the series
     "dax/bus.c: Fixups for dax-bus locking""

* tag 'mm-stable-2024-05-17-19-19' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (426 commits)
  memcg, oom: cleanup unused memcg_oom_gfp_mask and memcg_oom_order
  selftests/mm: hugetlb_madv_vs_map: avoid test skipping by querying hugepage size at runtime
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_wp
  mm/hugetlb: add missing VM_FAULT_SET_HINDEX in hugetlb_fault
  selftests: cgroup: add tests to verify the zswap writeback path
  mm: memcg: make alloc_mem_cgroup_per_node_info() return bool
  mm/damon/core: fix return value from damos_wmark_metric_value
  mm: do not update memcg stats for NR_{FILE/SHMEM}_PMDMAPPED
  selftests: cgroup: remove redundant enabling of memory controller
  Docs/mm/damon/maintainer-profile: allow posting patches based on damon/next tree
  Docs/mm/damon/maintainer-profile: change the maintainer's timezone from PST to PT
  Docs/mm/damon/design: use a list for supported filters
  Docs/admin-guide/mm/damon/usage: fix wrong schemes effective quota update command
  Docs/admin-guide/mm/damon/usage: fix wrong example of DAMOS filter matching sysfs file
  selftests/damon: classify tests for functionalities and regressions
  selftests/damon/_damon_sysfs: use 'is' instead of '==' for 'None'
  selftests/damon/_damon_sysfs: find sysfs mount point from /proc/mounts
  selftests/damon/_damon_sysfs: check errors from nr_schemes file reads
  mm/damon/core: initialize ->esz_bp from damos_quota_init_priv()
  selftests/damon: add a test for DAMOS quota goal
  ...
2024-05-19 09:21:03 -07:00
Linus Torvalds
ff9a79307f Merge tag 'kbuild-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild
Pull Kbuild updates from Masahiro Yamada:

 - Avoid 'constexpr', which is a keyword in C23

 - Allow 'dtbs_check' and 'dt_compatible_check' run independently of
   'dt_binding_check'

 - Fix weak references to avoid GOT entries in position-independent code
   generation

 - Convert the last use of 'optional' property in arch/sh/Kconfig

 - Remove support for the 'optional' property in Kconfig

 - Remove support for Clang's ThinLTO caching, which does not work with
   the .incbin directive

 - Change the semantics of $(src) so it always points to the source
   directory, which fixes Makefile inconsistencies between upstream and
   downstream

 - Fix 'make tar-pkg' for RISC-V to produce a consistent package

 - Provide reasonable default coverage for objtool, sanitizers, and
   profilers

 - Remove redundant OBJECT_FILES_NON_STANDARD, KASAN_SANITIZE, etc.

 - Remove the last use of tristate choice in drivers/rapidio/Kconfig

 - Various cleanups and fixes in Kconfig

* tag 'kbuild-v6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild: (46 commits)
  kconfig: use sym_get_choice_menu() in sym_check_prop()
  rapidio: remove choice for enumeration
  kconfig: lxdialog: remove initialization with A_NORMAL
  kconfig: m/nconf: merge two item_add_str() calls
  kconfig: m/nconf: remove dead code to display value of bool choice
  kconfig: m/nconf: remove dead code to display children of choice members
  kconfig: gconf: show checkbox for choice correctly
  kbuild: use GCOV_PROFILE and KCSAN_SANITIZE in scripts/Makefile.modfinal
  Makefile: remove redundant tool coverage variables
  kbuild: provide reasonable defaults for tool coverage
  modules: Drop the .export_symbol section from the final modules
  kconfig: use menu_list_for_each_sym() in sym_check_choice_deps()
  kconfig: use sym_get_choice_menu() in conf_write_defconfig()
  kconfig: add sym_get_choice_menu() helper
  kconfig: turn defaults and additional prompt for choice members into error
  kconfig: turn missing prompt for choice members into error
  kconfig: turn conf_choice() into void function
  kconfig: use linked list in sym_set_changed()
  kconfig: gconf: use MENU_CHANGED instead of SYMBOL_CHANGED
  kconfig: gconf: remove debug code
  ...
2024-05-18 12:39:20 -07:00
Linus Torvalds
d71ec0ed03 Merge tag 'x86-build-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 build updates from Ingo Molnar:

 - Use -fpic to build the kexec 'purgatory' (the self-contained
   code that runs between two kernels)

 - Clean up vmlinux.lds.S generation

 - Simplify the X86_EXTENDED_PLATFORM section of the x86 Kconfig

 - Misc cleanups & fixes

* tag 'x86-build-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/Kconfig: Merge the two CONFIG_X86_EXTENDED_PLATFORM entries
  x86/purgatory: Switch to the position-independent small code model
  x86/boot: Replace __PHYSICAL_START with LOAD_PHYSICAL_ADDR
  x86/vmlinux.lds.S: Take __START_KERNEL out conditional definition
  x86/vmlinux.lds.S: Remove conditional definition of LOAD_OFFSET
  vmlinux.lds.h: Fix a typo in comment
2024-05-13 18:05:08 -07:00
Linus Torvalds
9d8e0d52a2 Merge tag 'x86-boot-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 boot updates from Ingo Molnar:

 - Move the kernel cmdline setup earlier in the boot process (again),
   to address a split_lock_detect= boot parameter bug

 - Ignore relocations in .notes sections

 - Simplify boot stack setup

 - Re-introduce a bootloader quirk wrt CR4 handling

 - Miscellaneous cleanups & fixes

* tag 'x86-boot-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/boot/64: Clear most of CR4 in startup_64(), except PAE, MCE and LA57
  x86/boot: Move kernel cmdline setup earlier in the boot process (again)
  x86/build: Clean up arch/x86/tools/relocs.c a bit
  x86/boot: Ignore relocations in .notes sections in walk_relocs() too
  x86: Rename __{start,end}_init_task to __{start,end}_init_stack
  x86/boot: Simplify boot stack setup
2024-05-13 17:50:36 -07:00
Linus Torvalds
6e5a0c30b6 Merge tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:

 - Add cpufreq pressure feedback for the scheduler

 - Rework misfit load-balancing wrt affinity restrictions

 - Clean up and simplify the code around ::overutilized and
   ::overload access.

 - Simplify sched_balance_newidle()

 - Bump SCHEDSTAT_VERSION to 16 due to a cleanup of CPU_MAX_IDLE_TYPES
   handling that changed the output.

 - Rework & clean up <asm/vtime.h> interactions wrt arch_vtime_task_switch()

 - Reorganize, clean up and unify most of the higher level
   scheduler balancing function names around the sched_balance_*()
   prefix

 - Simplify the balancing flag code (sched_balance_running)

 - Miscellaneous cleanups & fixes

* tag 'sched-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
  sched/pelt: Remove shift of thermal clock
  sched/cpufreq: Rename arch_update_thermal_pressure() => arch_update_hw_pressure()
  thermal/cpufreq: Remove arch_update_thermal_pressure()
  sched/cpufreq: Take cpufreq feedback into account
  cpufreq: Add a cpufreq pressure feedback for the scheduler
  sched/fair: Fix update of rd->sg_overutilized
  sched/vtime: Do not include <asm/vtime.h> header
  s390/irq,nmi: Include <asm/vtime.h> header directly
  s390/vtime: Remove unused __ARCH_HAS_VTIME_TASK_SWITCH leftover
  sched/vtime: Get rid of generic vtime_task_switch() implementation
  sched/vtime: Remove confusing arch_vtime_task_switch() declaration
  sched/balancing: Simplify the sg_status bitmask and use separate ->overloaded and ->overutilized flags
  sched/fair: Rename set_rd_overutilized_status() to set_rd_overutilized()
  sched/fair: Rename SG_OVERLOAD to SG_OVERLOADED
  sched/fair: Rename {set|get}_rd_overload() to {set|get}_rd_overloaded()
  sched/fair: Rename root_domain::overload to ::overloaded
  sched/fair: Use helper functions to access root_domain::overload
  sched/fair: Check root_domain::overload value before update
  sched/fair: Combine EAS check with root_domain::overutilized access
  sched/fair: Simplify the continue_balancing logic in sched_balance_newidle()
  ...
2024-05-13 17:18:51 -07:00
Linus Torvalds
48fc82c40b Merge tag 'locking-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:

 - Over a dozen code generation micro-optimizations for the atomic
   and spinlock code

 - Add more __ro_after_init attributes

 - Robustify the lockdevent_*() macros

* tag 'locking-core-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/pvqspinlock/x86: Use _Q_LOCKED_VAL in PV_UNLOCK_ASM macro
  locking/qspinlock/x86: Micro-optimize virt_spin_lock()
  locking/atomic/x86: Merge __arch{,_try}_cmpxchg64_emu_local() with __arch{,_try}_cmpxchg64_emu()
  locking/atomic/x86: Introduce arch_try_cmpxchg64_local()
  locking/pvqspinlock/x86: Remove redundant CMP after CMPXCHG in __raw_callee_save___pv_queued_spin_unlock()
  locking/pvqspinlock: Use try_cmpxchg() in qspinlock_paravirt.h
  locking/pvqspinlock: Use try_cmpxchg_acquire() in trylock_clear_pending()
  locking/qspinlock: Use atomic_try_cmpxchg_relaxed() in xchg_tail()
  locking/atomic/x86: Define arch_atomic_sub() family using arch_atomic_add() functions
  locking/atomic/x86: Rewrite x86_32 arch_atomic64_{,fetch}_{and,or,xor}() functions
  locking/atomic/x86: Introduce arch_atomic64_read_nonatomic() to x86_32
  locking/atomic/x86: Introduce arch_atomic64_try_cmpxchg() to x86_32
  locking/atomic/x86: Introduce arch_try_cmpxchg64() for !CONFIG_X86_CMPXCHG64
  locking/atomic/x86: Modernize x86_32 arch_{,try_}_cmpxchg64{,_local}()
  locking/atomic/x86: Correct the definition of __arch_try_cmpxchg128()
  x86/tsc: Make __use_tsc __ro_after_init
  x86/kvm: Make kvm_async_pf_enabled __ro_after_init
  context_tracking: Make context_tracking_key __ro_after_init
  jump_label,module: Don't alloc static_key_mod for __ro_after_init keys
  locking/qspinlock: Always evaluate lockevent* non-event parameter once
2024-05-13 17:01:28 -07:00
Ard Biesheuvel
951bcae6c5 kallsyms: Avoid weak references for kallsyms symbols
kallsyms is a directory of all the symbols in the vmlinux binary, and so
creating it is somewhat of a chicken-and-egg problem, as its non-zero
size affects the layout of the binary, and therefore the values of the
symbols.

For this reason, the kernel is linked more than once, and the first pass
does not include any kallsyms data at all. For the linker to accept
this, the symbol declarations describing the kallsyms metadata are
emitted as having weak linkage, so they can remain unsatisfied. During
the subsequent passes, the weak references are satisfied by the kallsyms
metadata that was constructed based on information gathered from the
preceding passes.

Weak references lead to somewhat worse codegen, because taking their
address may need to produce NULL (if the reference was unsatisfied), and
this is not usually supported by RIP or PC relative symbol references.

Given that these references are ultimately always satisfied in the final
link, let's drop the weak annotation, and instead, provide fallback
definitions in the linker script that are only emitted if an unsatisfied
reference exists.

While at it, drop the FRV specific annotation that these symbols reside
in .rodata - FRV is long gone.

Tested-by: Nick Desaulniers <ndesaulniers@google.com> # Boot
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lkml.kernel.org/r/20230504174320.3930345-1-ardb%40kernel.org
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-05-02 19:48:26 +09:00
Suren Baghdasaryan
2c321f3f70 mm: change inlined allocation helpers to account at the call site
Main goal of memory allocation profiling patchset is to provide accounting
that is cheap enough to run in production.  To achieve that we inject
counters using codetags at the allocation call sites to account every time
allocation is made.  This injection allows us to perform accounting
efficiently because injected counters are immediately available as opposed
to the alternative methods, such as using _RET_IP_, which would require
counter lookup and appropriate locking that makes accounting much more
expensive.  This method requires all allocation functions to inject
separate counters at their call sites so that their callers can be
individually accounted.  Counter injection is implemented by allocation
hooks which should wrap all allocation functions.

Inlined functions which perform allocations but do not use allocation
hooks are directly charged for the allocations they perform.  In most
cases these functions are just specialized allocation wrappers used from
multiple places to allocate objects of a specific type.  It would be more
useful to do the accounting at their call sites instead.  Instrument these
helpers to do accounting at the call site.  Simple inlined allocation
wrappers are converted directly into macros.  More complex allocators or
allocators with documentation are converted into _noprof versions and
allocation hooks are added.  This allows memory allocation profiling
mechanism to charge allocations to the callers of these functions.

Link: https://lkml.kernel.org/r/20240415020731.1152108-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Jan Kara <jack@suse.cz>		[jbd2]
Cc: Anna Schumaker <anna@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Jakub Sitnicki <jakub@cloudflare.com>
Cc: Jiri Kosina <jikos@kernel.org>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:55:59 -07:00
Suren Baghdasaryan
22d407b164 lib: add allocation tagging support for memory allocation profiling
Introduce CONFIG_MEM_ALLOC_PROFILING which provides definitions to easily
instrument memory allocators.  It registers an "alloc_tags" codetag type
with /proc/allocinfo interface to output allocation tag information when
the feature is enabled.

CONFIG_MEM_ALLOC_PROFILING_DEBUG is provided for debugging the memory
allocation profiling instrumentation.

Memory allocation profiling can be enabled or disabled at runtime using
/proc/sys/vm/mem_profiling sysctl when CONFIG_MEM_ALLOC_PROFILING_DEBUG=n.
CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT enables memory allocation
profiling by default.

[surenb@google.com: Documentation/filesystems/proc.rst: fix allocinfo title]
  Link: https://lkml.kernel.org/r/20240326073813.727090-1-surenb@google.com
[surenb@google.com: do limited memory accounting for modules with ARCH_NEEDS_WEAK_PER_CPU]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-2-surenb@google.com
[klarasmodin@gmail.com: explicitly include irqflags.h in alloc_tag.h]
  Link: https://lkml.kernel.org/r/20240407133252.173636-1-klarasmodin@gmail.com
[surenb@google.com: fix alloc_tag_init() to prevent passing NULL to PTR_ERR()]
  Link: https://lkml.kernel.org/r/20240417003349.2520094-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-14-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Co-developed-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Klara Modin <klarasmodin@gmail.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:55:52 -07:00
Kent Overstreet
690da22dbf asm-generic/io.h: kill vmalloc.h dependency
Needed to avoid a new circular dependency with the memory allocation
profiling series.

Naturally, a whole bunch of files needed to include vmalloc.h that were
previously getting it implicitly.

Link: https://lkml.kernel.org/r/20240321163705.3067592-3-surenb@google.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:55:50 -07:00
Kent Overstreet
0069455bcb fix missing vmalloc.h includes
Patch series "Memory allocation profiling", v6.

Overview:
Low overhead [1] per-callsite memory allocation profiling. Not just for
debug kernels, overhead low enough to be deployed in production.

Example output:
  root@moria-kvm:~# sort -rn /proc/allocinfo
   127664128    31168 mm/page_ext.c:270 func:alloc_page_ext
    56373248     4737 mm/slub.c:2259 func:alloc_slab_page
    14880768     3633 mm/readahead.c:247 func:page_cache_ra_unbounded
    14417920     3520 mm/mm_init.c:2530 func:alloc_large_system_hash
    13377536      234 block/blk-mq.c:3421 func:blk_mq_alloc_rqs
    11718656     2861 mm/filemap.c:1919 func:__filemap_get_folio
     9192960     2800 kernel/fork.c:307 func:alloc_thread_stack_node
     4206592        4 net/netfilter/nf_conntrack_core.c:2567 func:nf_ct_alloc_hashtable
     4136960     1010 drivers/staging/ctagmod/ctagmod.c:20 [ctagmod] func:ctagmod_start
     3940352      962 mm/memory.c:4214 func:alloc_anon_folio
     2894464    22613 fs/kernfs/dir.c:615 func:__kernfs_new_node
     ...

Usage:
kconfig options:
 - CONFIG_MEM_ALLOC_PROFILING
 - CONFIG_MEM_ALLOC_PROFILING_ENABLED_BY_DEFAULT
 - CONFIG_MEM_ALLOC_PROFILING_DEBUG
   adds warnings for allocations that weren't accounted because of a
   missing annotation

sysctl:
  /proc/sys/vm/mem_profiling

Runtime info:
  /proc/allocinfo

Notes:

[1]: Overhead
To measure the overhead we are comparing the following configurations:
(1) Baseline with CONFIG_MEMCG_KMEM=n
(2) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)
(3) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y)
(4) Enabled at runtime (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n && /proc/sys/vm/mem_profiling=1)
(5) Baseline with CONFIG_MEMCG_KMEM=y && allocating with __GFP_ACCOUNT
(6) Disabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=n)  && CONFIG_MEMCG_KMEM=y
(7) Enabled by default (CONFIG_MEM_ALLOC_PROFILING=y &&
    CONFIG_MEM_ALLOC_PROFILING_BY_DEFAULT=y) && CONFIG_MEMCG_KMEM=y

Performance overhead:
To evaluate performance we implemented an in-kernel test executing
multiple get_free_page/free_page and kmalloc/kfree calls with allocation
sizes growing from 8 to 240 bytes with CPU frequency set to max and CPU
affinity set to a specific CPU to minimize the noise. Below are results
from running the test on Ubuntu 22.04.2 LTS with 6.8.0-rc1 kernel on
56 core Intel Xeon:

                        kmalloc                 pgalloc
(1 baseline)            6.764s                  16.902s
(2 default disabled)    6.793s  (+0.43%)        17.007s (+0.62%)
(3 default enabled)     7.197s  (+6.40%)        23.666s (+40.02%)
(4 runtime enabled)     7.405s  (+9.48%)        23.901s (+41.41%)
(5 memcg)               13.388s (+97.94%)       48.460s (+186.71%)
(6 def disabled+memcg)  13.332s (+97.10%)       48.105s (+184.61%)
(7 def enabled+memcg)   13.446s (+98.78%)       54.963s (+225.18%)

Memory overhead:
Kernel size:

   text           data        bss         dec         diff
(1) 26515311	      18890222    17018880    62424413
(2) 26524728	      19423818    16740352    62688898    264485
(3) 26524724	      19423818    16740352    62688894    264481
(4) 26524728	      19423818    16740352    62688898    264485
(5) 26541782	      18964374    16957440    62463596    39183

Memory consumption on a 56 core Intel CPU with 125GB of memory:
Code tags:           192 kB
PageExts:         262144 kB (256MB)
SlabExts:           9876 kB (9.6MB)
PcpuExts:            512 kB (0.5MB)

Total overhead is 0.2% of total memory.

Benchmarks:

Hackbench tests run 100 times:
hackbench -s 512 -l 200 -g 15 -f 25 -P
      baseline       disabled profiling           enabled profiling
avg   0.3543         0.3559 (+0.0016)             0.3566 (+0.0023)
stdev 0.0137         0.0188                       0.0077


hackbench -l 10000
      baseline       disabled profiling           enabled profiling
avg   6.4218         6.4306 (+0.0088)             6.5077 (+0.0859)
stdev 0.0933         0.0286                       0.0489

stress-ng tests:
stress-ng --class memory --seq 4 -t 60
stress-ng --class cpu --seq 4 -t 60
Results posted at: https://evilpiepirate.org/~kent/memalloc_prof_v4_stress-ng/

[2] https://lore.kernel.org/all/20240306182440.2003814-1-surenb@google.com/


This patch (of 37):

The next patch drops vmalloc.h from a system header in order to fix a
circular dependency; this adds it to all the files that were pulling it in
implicitly.

[kent.overstreet@linux.dev: fix arch/alpha/lib/memcpy.c]
  Link: https://lkml.kernel.org/r/20240327002152.3339937-1-kent.overstreet@linux.dev
[surenb@google.com: fix arch/x86/mm/numa_32.c]
  Link: https://lkml.kernel.org/r/20240402180933.1663992-1-surenb@google.com
[kent.overstreet@linux.dev: a few places were depending on sizes.h]
  Link: https://lkml.kernel.org/r/20240404034744.1664840-1-kent.overstreet@linux.dev
[arnd@arndb.de: fix mm/kasan/hw_tags.c]
  Link: https://lkml.kernel.org/r/20240404124435.3121534-1-arnd@kernel.org
[surenb@google.com: fix arc build]
  Link: https://lkml.kernel.org/r/20240405225115.431056-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-1-surenb@google.com
Link: https://lkml.kernel.org/r/20240321163705.3067592-2-surenb@google.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Tested-by: Kees Cook <keescook@chromium.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andreas Hindborg <a.hindborg@samsung.com>
Cc: Benno Lossin <benno.lossin@proton.me>
Cc: "Björn Roy Baron" <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Gary Guo <gary@garyguo.net>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-04-25 20:55:49 -07:00
Alexander Gordeev
08a36a4854 sched/vtime: Do not include <asm/vtime.h> header
There is no architecture-specific code or data left
that generic <linux/vtime.h> needs to know about.
Thus, avoid the inclusion of <asm/vtime.h> header.

Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Nicholas Piggin <npiggin@gmail.com>
Link: https://lore.kernel.org/r/f7cd245668b9ae61a55184871aec494ec9199c4a.1712760275.git.agordeev@linux.ibm.com
2024-04-17 13:37:23 +02:00
Mathieu Desnoyers
fe90f3967b sched: Add missing memory barrier in switch_mm_cid
Many architectures' switch_mm() (e.g. arm64) do not have an smp_mb()
which the core scheduler code has depended upon since commit:

    commit 223baf9d17 ("sched: Fix performance regression introduced by mm_cid")

If switch_mm() doesn't call smp_mb(), sched_mm_cid_remote_clear() can
unset the actively used cid when it fails to observe active task after it
sets lazy_put.

There *is* a memory barrier between storing to rq->curr and _return to
userspace_ (as required by membarrier), but the rseq mm_cid has stricter
requirements: the barrier needs to be issued between store to rq->curr
and switch_mm_cid(), which happens earlier than:

  - spin_unlock(),
  - switch_to().

So it's fine when the architecture switch_mm() happens to have that
barrier already, but less so when the architecture only provides the
full barrier in switch_to() or spin_unlock().

It is a bug in the rseq switch_mm_cid() implementation. All architectures
that don't have memory barriers in switch_mm(), but rather have the full
barrier either in finish_lock_switch() or switch_to() have them too late
for the needs of switch_mm_cid().

Introduce a new smp_mb__after_switch_mm(), defined as smp_mb() in the
generic barrier.h header, and use it in switch_mm_cid() for scheduler
transitions where switch_mm() is expected to provide a memory barrier.

Architectures can override smp_mb__after_switch_mm() if their
switch_mm() implementation provides an implicit memory barrier.
Override it with a no-op on x86 which implicitly provide this memory
barrier by writing to CR3.

Fixes: 223baf9d17 ("sched: Fix performance regression introduced by mm_cid")
Reported-by: levi.yun <yeoreum.yun@arm.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> # for arm64
Acked-by: Dave Hansen <dave.hansen@linux.intel.com> # for x86
Cc: <stable@vger.kernel.org> # 6.4.x
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240415152114.59122-2-mathieu.desnoyers@efficios.com
2024-04-16 13:59:45 +02:00
Linus Torvalds
c748fc3b1f Merge tag 'timers-urgent-2024-04-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Ingo Molnar:

 - Address a (valid) W=1 build warning

 - Fix timer self-tests

 - Annotate a KCSAN warning wrt. accesses to the tick_do_timer_cpu
   global variable

 - Address a !CONFIG_BUG build warning

* tag 'timers-urgent-2024-04-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  selftests: kselftest: Fix build failure with NOLIBC
  selftests: timers: Fix abs() warning in posix_timers test
  selftests: kselftest: Mark functions that unconditionally call exit() as __noreturn
  selftests: timers: Fix posix_timers ksft_print_msg() warning
  selftests: timers: Fix valid-adjtimex signed left-shift undefined behavior
  bug: Fix no-return-statement warning with !CONFIG_BUG
  timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu
  selftests/timers/posix_timers: Reimplement check_timer_distribution()
  irqflags: Explicitly ignore lockdep_hrtimer_exit() argument
2024-04-14 10:32:22 -07:00
Linus Torvalds
52e5070f60 Merge tag 'hyperv-fixes-signed-20240411' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyperv fixes from Wei Liu:

 - Some cosmetic changes (Erni Sri Satya Vennela, Li Zhijian)

 - Introduce hv_numa_node_to_pxm_info() (Nuno Das Neves)

 - Fix KVP daemon to handle IPv4 and IPv6 combination for keyfile format
   (Shradha Gupta)

 - Avoid freeing decrypted memory in a confidential VM (Rick Edgecombe
   and Michael Kelley)

* tag 'hyperv-fixes-signed-20240411' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  Drivers: hv: vmbus: Don't free ring buffers that couldn't be re-encrypted
  uio_hv_generic: Don't free decrypted memory
  hv_netvsc: Don't free decrypted memory
  Drivers: hv: vmbus: Track decrypted status in vmbus_gpadl
  Drivers: hv: vmbus: Leak pages if set_memory_encrypted() fails
  hv/hv_kvp_daemon: Handle IPv4 and Ipv6 combination for keyfile format
  hv: vmbus: Convert sprintf() family to sysfs_emit() family
  mshyperv: Introduce hv_numa_node_to_pxm_info()
  x86/hyperv: Cosmetic changes for hv_apic.c
2024-04-11 16:23:56 -07:00
Ingo Molnar
5b9b2e6baf Merge tag 'v6.9-rc3' into x86/boot, to pick up fixes before queueing up more changes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-04-11 15:36:23 +02:00
Adrian Hunter
5284984a4f bug: Fix no-return-statement warning with !CONFIG_BUG
BUG() does not return, and arch implementations of BUG() use unreachable()
or other non-returning code. However with !CONFIG_BUG, the default
implementation is often used instead, and that does not do that. x86 always
uses its own implementation, but powerpc with !CONFIG_BUG gives a build
error:

  kernel/time/timekeeping.c: In function ‘timekeeping_debug_get_ns’:
  kernel/time/timekeeping.c:286:1: error: no return statement in function
  returning non-void [-Werror=return-type]

Add unreachable() to default !CONFIG_BUG BUG() implementation.

Fixes: e8e9d21a5d ("timekeeping: Refactor timekeeping helpers")
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Link: https://lore.kernel.org/r/20240410153212.127477-1-adrian.hunter@intel.com
Closes: https://lore.kernel.org/all/CA+G9fYvjdZCW=7ZGxS6A_3bysjQ56YF7S-+PNLQ_8a4DKh1Bhg@mail.gmail.com/
2024-04-10 22:01:35 +02:00
Ingo Molnar
d1eec383a8 Merge tag 'v6.9-rc3' into locking/core, to pick up fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2024-04-09 09:48:09 +02:00
Masahiro Yamada
0316e4b04e export.h: remove include/asm-generic/export.h
Commit 3a6dd5f614 ("riscv: remove unneeded #include
<asm-generic/export.h>") removed the last use of
include/asm-generic/export.h.

This deprecated header can go away.

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
2024-03-28 11:04:20 +09:00
Nuno Das Neves
1f1dc442c5 mshyperv: Introduce hv_numa_node_to_pxm_info()
Factor out logic for converting numa node to hv_proximity_domain_info
into a helper function.

Change hv_proximity_domain_info to a struct to improve readability.

While at it, rename hv_add_logical_processor_* structs to the correct
hv_input_/hv_output_ prefix, and remove the flags field which is not
present in the ABI.

Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Link: https://lore.kernel.org/r/1711141826-9458-1-git-send-email-nunodasneves@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <1711141826-9458-1-git-send-email-nunodasneves@linux.microsoft.com>
2024-03-22 23:40:36 +00:00
Linus Torvalds
c150b809f7 Merge tag 'riscv-for-linus-6.9-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:

 - Support for various vector-accelerated crypto routines

 - Hibernation is now enabled for portable kernel builds

 - mmap_rnd_bits_max is larger on systems with larger VAs

 - Support for fast GUP

 - Support for membarrier-based instruction cache synchronization

 - Support for the Andes hart-level interrupt controller and PMU

 - Some cleanups around unaligned access speed probing and Kconfig
   settings

 - Support for ACPI LPI and CPPC

 - Various cleanus related to barriers

 - A handful of fixes

* tag 'riscv-for-linus-6.9-mw2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (66 commits)
  riscv: Fix syscall wrapper for >word-size arguments
  crypto: riscv - add vector crypto accelerated AES-CBC-CTS
  crypto: riscv - parallelize AES-CBC decryption
  riscv: Only flush the mm icache when setting an exec pte
  riscv: Use kcalloc() instead of kzalloc()
  riscv/barrier: Add missing space after ','
  riscv/barrier: Consolidate fence definitions
  riscv/barrier: Define RISCV_FULL_BARRIER
  riscv/barrier: Define __{mb,rmb,wmb}
  RISC-V: defconfig: Enable CONFIG_ACPI_CPPC_CPUFREQ
  cpufreq: Move CPPC configs to common Kconfig and add RISC-V
  ACPI: RISC-V: Add CPPC driver
  ACPI: Enable ACPI_PROCESSOR for RISC-V
  ACPI: RISC-V: Add LPI driver
  cpuidle: RISC-V: Move few functions to arch/riscv
  riscv: Introduce set_compat_task() in asm/compat.h
  riscv: Introduce is_compat_thread() into compat.h
  riscv: add compile-time test into is_compat_task()
  riscv: Replace direct thread flag check with is_compat_task()
  riscv: Improve arch_get_mmap_end() macro
  ...
2024-03-22 10:41:13 -07:00
Peter Zijlstra
91a1d97ef4 jump_label,module: Don't alloc static_key_mod for __ro_after_init keys
When a static_key is marked ro_after_init, its state will never change
(after init), therefore jump_label_update() will never need to iterate
the entries, and thus module load won't actually need to track this --
avoiding the static_key::next write.

Therefore, mark these keys such that jump_label_add_module() might
recognise them and avoid the modification.

Use the special state: 'static_key_linked(key) && !static_key_mod(key)'
to denote such keys.

jump_label_add_module() does not exist under CONFIG_JUMP_LABEL=n, so the
newly-introduced jump_label_init_ro() can be defined as a nop for that
configuration.

[ mingo: Renamed jump_label_ro() to jump_label_init_ro() ]

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Link: https://lore.kernel.org/r/20240313180106.2917308-2-vschneid@redhat.com
2024-03-22 11:18:16 +01:00
Xin Li (Intel)
8f69cba096 x86: Rename __{start,end}_init_task to __{start,end}_init_stack
The stack of a task has been separated from the memory of a task_struct
struture for a long time on x86, as a result __{start,end}_init_task no
longer mark the start and end of the init_task structure, but its stack
only.

Rename __{start,end}_init_task to __{start,end}_init_stack.

Note other architectures are not affected because __{start,end}_init_task
are used on x86 only.

Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Juergen Gross <jgross@suse.com>
Link: https://lore.kernel.org/r/20240322081616.3346181-1-xin@zytor.com
2024-03-22 09:32:41 +01:00
Linus Torvalds
cfce216e14 Merge tag 'hyperv-next-signed-20240320' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux
Pull hyperv updates from Wei Liu:

 - Use Hyper-V entropy to seed guest random number generator (Michael
   Kelley)

 - Convert to platform remove callback returning void for vmbus (Uwe
   Kleine-König)

 - Introduce hv_get_hypervisor_version function (Nuno Das Neves)

 - Rename some HV_REGISTER_* defines for consistency (Nuno Das Neves)

 - Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_* (Nuno Das
   Neves)

 - Cosmetic changes for hv_spinlock.c (Purna Pavan Chandra Aekkaladevi)

 - Use per cpu initial stack for vtl context (Saurabh Sengar)

* tag 'hyperv-next-signed-20240320' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  x86/hyperv: Use Hyper-V entropy to seed guest random number generator
  x86/hyperv: Cosmetic changes for hv_spinlock.c
  hyperv-tlfs: Rename some HV_REGISTER_* defines for consistency
  hv: vmbus: Convert to platform remove callback returning void
  mshyperv: Introduce hv_get_hypervisor_version function
  x86/hyperv: Use per cpu initial stack for vtl context
  hyperv-tlfs: Change prefix of generic HV_REGISTER_* MSRs to HV_MSR_*
2024-03-21 10:01:02 -07:00
Michael Kelley
f2580a907e x86/hyperv: Use Hyper-V entropy to seed guest random number generator
A Hyper-V host provides its guest VMs with entropy in a custom ACPI
table named "OEM0".  The entropy bits are updated each time Hyper-V
boots the VM, and are suitable for seeding the Linux guest random
number generator (rng). See a brief description of OEM0 in [1].

Generation 2 VMs on Hyper-V use UEFI to boot. Existing EFI code in
Linux seeds the rng with entropy bits from the EFI_RNG_PROTOCOL.
Via this path, the rng is seeded very early during boot with good
entropy. The ACPI OEM0 table provided in such VMs is an additional
source of entropy.

Generation 1 VMs on Hyper-V boot from BIOS. For these VMs, Linux
doesn't currently get any entropy from the Hyper-V host. While this
is not fundamentally broken because Linux can generate its own entropy,
using the Hyper-V host provided entropy would get the rng off to a
better start and would do so earlier in the boot process.

Improve the rng seeding for Generation 1 VMs by having Hyper-V specific
code in Linux take advantage of the OEM0 table to seed the rng. For
Generation 2 VMs, use the OEM0 table to provide additional entropy
beyond the EFI_RNG_PROTOCOL. Because the OEM0 table is custom to
Hyper-V, parse it directly in the Hyper-V code in the Linux kernel
and use add_bootloader_randomness() to add it to the rng. Once the
entropy bits are read from OEM0, zero them out in the table so
they don't appear in /sys/firmware/acpi/tables/OEM0 in the running
VM. The zero'ing is done out of an abundance of caution to avoid
potential security risks to the rng. Also set the OEM0 data length
to zero so a kexec or other subsequent use of the table won't try
to use the zero'ed bits.

[1] https://download.microsoft.com/download/1/c/9/1c9813b8-089c-4fef-b2ad-ad80e79403ba/Whitepaper%20-%20The%20Windows%2010%20random%20number%20generation%20infrastructure.pdf

Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20240318155408.216851-1-mhklinux@outlook.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20240318155408.216851-1-mhklinux@outlook.com>
2024-03-18 22:01:52 +00:00