While workqueue.default_affinity_scope is writable, it only affects
workqueues which are created afterwards and isn't very useful. Instead,
let's introduce explicit "default" scope and update the effective scope
dynamically when workqueue.default_affinity_scope is changed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Add three more affinity scopes - WQ_AFFN_CPU, SMT and CACHE - and make CACHE
the default. The code changes to actually add the additional scopes are
trivial.
Also add module parameter "workqueue.default_affinity_scope" to override the
default scope and "affinity_scope" sysfs file to configure it per workqueue.
wq_dump.py and documentations are updated accordingly.
This enables significant flexibility in configuring how unbound workqueues
behave. If affinity scope is set to "cpu", it'll behave close to a per-cpu
workqueue. On the other hand, "system" removes all locality boundaries.
Many modern machines have multiple L3 caches often while being mostly
uniform in terms of memory access. Thus, workqueue's previous behavior of
spreading work items in each NUMA node had negative performance implications
from unncessarily crossing L3 boundaries between issue and execution.
However, picking a finer grained affinity scope also has a downside in that
an issuer in one group can't utilize CPUs in other groups.
While dependent on the specifics of workload, there's usually a noticeable
penalty in crossing L3 boundaries, so let's default to CACHE. This issue
will be further addressed and documented with examples in future patches.
Signed-off-by: Tejun Heo <tj@kernel.org>
Unbound workqueue CPU affinity is going to receive an overhaul and the NUMA
specific knobs won't make sense anymore. Remove them. Also, the pool_ids
knob was used for debugging and not really meaningful given that there is no
visibility into the pools associated with those IDs. Remove it too. A future
patch will improve overall visibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull x86/gds fixes from Dave Hansen:
"Mitigate Gather Data Sampling issue:
- Add Base GDS mitigation
- Support GDS_NO under KVM
- Fix a documentation typo"
* tag 'gds-for-linus-2023-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
Documentation/x86: Fix backwards on/off logic about YMM support
KVM: Add GDS_NO support to KVM
x86/speculation: Add Kconfig option for GDS
x86/speculation: Add force option to GDS mitigation
x86/speculation: Add Gather Data Sampling mitigation
Add support for HOTPLUG_SMT, which enables the generic sysfs SMT support
files in /sys/devices/system/cpu/smt, as well as the "nosmt" boot
parameter.
Implement the recently added hooks to allow partial SMT states, allow
any number of threads per core.
Tie the config symbol to HOTPLUG_CPU, which enables it on the major
platforms that support SMT. If there are other platforms that want the
SMT support that can be tweaked in future.
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
[ldufour: remove topology_smt_supported]
[ldufour: remove topology_smt_threads_supported]
[ldufour: select CONFIG_SMT_NUM_THREADS_DYNAMIC]
[ldufour: update kernel-parameters.txt]
Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Link: https://msgid.link/20230705145143.40545-10-ldufour@linux.ibm.com
The kernel parameter 'cma_pernuma=' only supports reserving the same
size of CMA area for each node. We need to reserve different sizes of
CMA area for specified nodes if these devices belong to different nodes.
Adding another kernel parameter 'numa_cma=' to reserve CMA area for
the specified node. If we want to use one of these parameters, we need to
enable DMA_NUMA_CMA.
At the same time, print the node id in cma_declare_contiguous_nid() if
CONFIG_NUMA is enabled.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Signed-off-by: Christoph Hellwig <hch@lst.de>
In the commit b7176c261c ("dma-contiguous: provide the ability to
reserve per-numa CMA"), Barry adds DMA_PERNUMA_CMA for ARM64.
But this feature is architecture independent, so support per-numa CMA
for all architectures, and enable it by default if NUMA.
Signed-off-by: Yajun Deng <yajun.deng@linux.dev>
Tested-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Add a mitigation for the speculative return address stack overflow
vulnerability found on AMD processors.
The mitigation works by ensuring all RET instructions speculate to
a controlled location, similar to how speculation is controlled in the
retpoline sequence. To accomplish this, the __x86_return_thunk forces
the CPU to mispredict every function return using a 'safe return'
sequence.
To ensure the safety of this mitigation, the kernel must ensure that the
safe return sequence is itself free from attacker interference. In Zen3
and Zen4, this is accomplished by creating a BTB alias between the
untraining function srso_untrain_ret_alias() and the safe return
function srso_safe_ret_alias() which results in evicting a potentially
poisoned BTB entry and using that safe one for all function returns.
In older Zen1 and Zen2, this is accomplished using a reinterpretation
technique similar to Retbleed one: srso_untrain_ret() and
srso_safe_ret().
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
As it says on the tin, provide Kconfig option to control parsing the
"riscv,isa" devicetree property. If either option is used, the kernel
will fall back to parsing "riscv,isa", where "riscv,isa-base" and
"riscv,isa-extensions" are not present.
The Kconfig options are set up so that the default kernel configuration
will enable the fallback path, without needing the commandline option.
Suggested-by: Andrew Jones <ajones@ventanamicro.com>
Suggested-by: Palmer Dabbelt <palmer@rivosinc.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230713-aviator-plausibly-a35662485c2c@wendy
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
The Gather Data Sampling (GDS) vulnerability allows malicious software
to infer stale data previously stored in vector registers. This may
include sensitive data such as cryptographic keys. GDS is mitigated in
microcode, and systems with up-to-date microcode are protected by
default. However, any affected system that is running with older
microcode will still be vulnerable to GDS attacks.
Since the gather instructions used by the attacker are part of the
AVX2 and AVX512 extensions, disabling these extensions prevents gather
instructions from being executed, thereby mitigating the system from
GDS. Disabling AVX2 is sufficient, but we don't have the granularity
to do this. The XCR0[2] disables AVX, with no option to just disable
AVX2.
Add a kernel parameter gather_data_sampling=force that will enable the
microcode mitigation if available, otherwise it will disable AVX on
affected systems.
This option will be ignored if cmdline mitigations=off.
This is a *big* hammer. It is known to break buggy userspace that
uses incomplete, buggy AVX enumeration. Unfortunately, such userspace
does exist in the wild:
https://www.mail-archive.com/bug-coreutils@gnu.org/msg33046.html
[ dhansen: add some more ominous warnings about disabling AVX ]
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Gather Data Sampling (GDS) is a hardware vulnerability which allows
unprivileged speculative access to data which was previously stored in
vector registers.
Intel processors that support AVX2 and AVX512 have gather instructions
that fetch non-contiguous data elements from memory. On vulnerable
hardware, when a gather instruction is transiently executed and
encounters a fault, stale data from architectural or internal vector
registers may get transiently stored to the destination vector
register allowing an attacker to infer the stale data using typical
side channel techniques like cache timing attacks.
This mitigation is different from many earlier ones for two reasons.
First, it is enabled by default and a bit must be set to *DISABLE* it.
This is the opposite of normal mitigation polarity. This means GDS can
be mitigated simply by updating microcode and leaving the new control
bit alone.
Second, GDS has a "lock" bit. This lock bit is there because the
mitigation affects the hardware security features KeyLocker and SGX.
It needs to be enabled and *STAY* enabled for these features to be
mitigated against GDS.
The mitigation is enabled in the microcode by default. Disable it by
setting gather_data_sampling=off or by disabling all mitigations with
mitigations=off. The mitigation status can be checked by reading:
/sys/devices/system/cpu/vulnerabilities/gather_data_sampling
Signed-off-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
The `nocrt` module parameter has no code associated with it and does
nothing. As `crt=-1` has same functionality as what nocrt should be
doing drop `nocrt` and associated documentation.
This should fix a quirk for Gigabyte GA-7ZX that used `nocrt` and
thus didn't function properly.
Fixes: 8c99fdce30 ("ACPI: thermal: set "thermal.nocrt" via DMI on Gigabyte GA-7ZX")
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
This commit adds the kfree_by_call_rcu and kfree_mult rcuscale module
parameters to kernel-parameters.txt. While in the area, it updates
to rcuscale.scale_type.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
By default, rcuscale collects only 100 points of data per writer, but
arranging for all kthreads to be actively collecting (if not recording)
data during the time that any kthread might be recording. This works
well, but does not allow much time to bring external performance tools
to bear. This commit therefore adds a minruntime module parameter
that specifies a minimum data-collection interval in seconds.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Some workloads do isolated RCU work, and this can affect operation
latencies. This commit therefore adds a writer_holdoff_jiffies module
parameter that causes writers to block for the specified number of
jiffies between each pair of consecutive write-side operations.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The various RCU Tasks flavors now do lazy grace periods when there are
only asynchronous grace period requests. By default, the system will let
250 milliseconds elapse after the first call_rcu_tasks*() callbacki is
queued before starting a grace period. In contrast, synchronous grace
period requests such as synchronize_rcu_tasks*() will start a grace
period immediately.
However, invoking one of the call_rcu_tasks*() functions in a too-tight
loop can result in a callback flood, which in turn can exhaust memory
if grace periods are delayed for too long.
This commit therefore sets a limit so that the grace-period kthread
will be awakened when any CPU's callback list expands to contain
rcupdate.rcu_task_lazy_lim callbacks elements (defaulting to 32, set to -1
to disable), the grace-period kthread will be awakened, thus cancelling
any ongoing laziness and getting out in front of the potential callback
flood.
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This commit adds kernel boot parameters for callback laziness, allowing
the RCU Tasks flavors to be individually adjusted.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Motivation of doing this is to better improve boot times for devices when
we want to prevent our workqueue works from running on some specific CPUs,
e,g, some CPUs are busy with interrupts.
Signed-off-by: tiozhang <tiozhang@didiglobal.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull mode documentation updates from Jonathan Corbet:
"A half-dozen late arriving docs patches. They are mostly fixes, but we
also have a kernel-doc tweak for enums and the long-overdue removal of
the outdated and redundant patch-submission comments at the top of the
MAINTAINERS file"
* tag 'docs-6.5-2' of git://git.lwn.net/linux:
scripts: kernel-doc: support private / public marking for enums
Documentation: KVM: SEV: add a missing backtick
Documentation: ACPI: fix typo in ssdt-overlays.rst
Fix documentation of panic_on_warn
docs: remove the tips on how to submit patches from MAINTAINERS
docs: fix typo in zh_TW and zh_CN translation
The kernel cmdline option panic_on_warn expects an integer, it is not a
plain option as documented. A number of uses in the tree figured this
already, and use panic_on_warn=1 for their purpose.
Adjust a comment which otherwise may mislead people in the future.
Fixes: 9e3961a097 ("kernel: add panic_on_warn")
Signed-off-by: Olaf Hering <olaf@aepfle.de>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Pull RISC-V updates from Palmer Dabbelt:
- Support for ACPI
- Various cleanups to the ISA string parsing, including making them
case-insensitive
- Support for the vector extension
- Support for independent irq/softirq stacks
- Our CPU DT binding now has "unevaluatedProperties: false"
* tag 'riscv-for-linus-6.5-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (78 commits)
riscv: hibernate: remove WARN_ON in save_processor_state
dt-bindings: riscv: cpus: switch to unevaluatedProperties: false
dt-bindings: riscv: cpus: add a ref the common cpu schema
riscv: stack: Add config of thread stack size
riscv: stack: Support HAVE_SOFTIRQ_ON_OWN_STACK
riscv: stack: Support HAVE_IRQ_EXIT_ON_IRQ_STACK
RISC-V: always report presence of extensions formerly part of the base ISA
dt-bindings: riscv: explicitly mention assumption of Zicntr & Zihpm support
RISC-V: remove decrement/increment dance in ISA string parser
RISC-V: rework comments in ISA string parser
RISC-V: validate riscv,isa at boot, not during ISA string parsing
RISC-V: split early & late of_node to hartid mapping
RISC-V: simplify register width check in ISA string parsing
perf: RISC-V: Limit the number of counters returned from SBI
riscv: replace deprecated scall with ecall
riscv: uprobes: Restore thread.bad_cause
riscv: mm: try VMA lock-based page fault handling first
riscv: mm: Pre-allocate PGD entries for vmalloc/modules area
RISC-V: hwprobe: Expose Zba, Zbb, and Zbs
RISC-V: Track ISA extensions per hart
...
Pull iommu updates from Joerg Roedel:
"Core changes:
- iova_magazine_alloc() optimization
- Make flush-queue an IOMMU driver capability
- Consolidate the error handling around device attachment
AMD IOMMU changes:
- AVIC Interrupt Remapping Improvements
- Some minor fixes and cleanups
Intel VT-d changes from Lu Baolu:
- Small and misc cleanups
ARM-SMMU changes from Will Deacon:
- Device-tree binding updates:
- Add missing clocks for SC8280XP and SA8775 Adreno SMMUs
- Add two new Qualcomm SMMUs in SDX75 and SM6375
- Workarounds for Arm MMU-700 errata:
- 1076982: Avoid use of SEV-based cmdq wakeup
- 2812531: Terminate command batches with a CMD_SYNC
- Enforce single-stage translation to avoid nesting-related errata
- Set the correct level hint for range TLB invalidation on teardown
.. and some other minor fixes and cleanups (including Freescale PAMU
and virtio-iommu changes)"
* tag 'iommu-updates-v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu: (50 commits)
iommu/vt-d: Remove commented-out code
iommu/vt-d: Remove two WARN_ON in domain_context_mapping_one()
iommu/vt-d: Handle the failure case of dmar_reenable_qi()
iommu/vt-d: Remove unnecessary (void*) conversions
iommu/amd: Remove extern from function prototypes
iommu/amd: Use BIT/BIT_ULL macro to define bit fields
iommu/amd: Fix DTE_IRQ_PHYS_ADDR_MASK macro
iommu/amd: Fix compile error for unused function
iommu/amd: Improving Interrupt Remapping Table Invalidation
iommu/amd: Do not Invalidate IRT when IRTE caching is disabled
iommu/amd: Introduce Disable IRTE Caching Support
iommu/amd: Remove the unused struct amd_ir_data.ref
iommu/amd: Switch amd_iommu_update_ga() to use modify_irte_ga()
iommu/arm-smmu-v3: Set TTL invalidation hint better
iommu/arm-smmu-v3: Document nesting-related errata
iommu/arm-smmu-v3: Add explicit feature for nesting
iommu/arm-smmu-v3: Document MMU-700 erratum 2812531
iommu/arm-smmu-v3: Work around MMU-600 erratum 1076982
dt-bindings: arm-smmu: Add SDX75 SMMU compatible
dt-bindings: arm-smmu: Add SM6375 GPU SMMU
...
Pull MIPS updates from Thomas Bogendoerfer:
- add support for TP-Link HC220 G5 v1
- add support for Wifi/Bluetooth on CI20
- rework Ralink clock and reset handling
- cleanups and fixes
* tag 'mips_6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/mips/linux: (58 commits)
MIPS: Loongson64: DTS: Add RTC support to Loongson-2K1000
MIPS: Loongson64: DTS: Add RTC support to LS7A PCH
MIPS: OCTEON: octeon-usb: cleanup divider calculation
MIPS: OCTEON: octeon-usb: introduce dwc3_octeon_{read,write}q
MIPS: OCTEON: octeon-usb: move gpio config to separate function
MIPS: OCTEON: octeon-usb: use bitfields for shim register
MIPS: OCTEON: octeon-usb: use bitfields for host config register
MIPS: OCTEON: octeon-usb: use bitfields for control register
MIPS: OCTEON: octeon-usb: add all register offsets
mips: ralink: match all supported system controller compatible strings
MIPS: dec: prom: Address -Warray-bounds warning
MIPS: DTS: CI20: Raise VDDCORE voltage to 1.125 volts
clk: ralink: mtmips: Fix uninitialized use of ret in mtmips_register_{fixed,factor}_clocks()
mips: ralink: introduce commonly used remap node function
mips: pci-mt7620: use dev_info() to log PCIe device detection result
mips: pci-mt7620: do not print NFTS register value as error log
MAINTAINERS: add Mediatek MTMIPS Clock maintainer
mips: ralink: get cpu rate from new driver code
mips: ralink: remove reset related code
mips: ralink: mt7620: remove clock related code
...
Pull arm64 documentation move from Jonathan Corbet:
"Move the arm64 architecture documentation under Documentation/arch/.
This brings some order to the documentation directory, declutters the
top-level directory, and makes the documentation organization more
closely match that of the source"
* tag 'docs-arm64-move' of git://git.lwn.net/linux:
perf arm-spe: Fix a dangling Documentation/arm64 reference
mm: Fix a dangling Documentation/arm64 reference
arm64: Fix dangling references to Documentation/arm64
dt-bindings: fix dangling Documentation/arm64 reference
docs: arm64: Move arm64 documentation under Documentation/arch/
Pull workqueue updates from Tejun Heo:
- Concurrency-managed per-cpu work items that hog CPUs and delay the
execution of other work items are now automatically detected and
excluded from concurrency management. Reporting on such work items
can also be enabled through a config option.
- Added tools/workqueue/wq_monitor.py which improves visibility into
workqueue usages and behaviors.
- Arnd's minimal fix for gcc-13 enum warning on 32bit compiles,
superseded by commit afa4bb778e in mainline.
* tag 'wq-for-6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: Disable per-cpu CPU hog detection when wq_cpu_intensive_thresh_us is 0
workqueue: Fix WARN_ON_ONCE() triggers in worker_enter_idle()
workqueue: fix enum type for gcc-13
workqueue: Track and monitor per-workqueue CPU time usage
workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism
workqueue: Automatically mark CPU-hogging work items CPU_INTENSIVE
workqueue: Improve locking rule description for worker fields
workqueue: Move worker_set/clr_flags() upwards
workqueue: Re-order struct worker fields
workqueue: Add pwq->stats[] and a monitoring script
Further upgrade queue_work_on() comment
Pull objtool updates from Ingo Molar:
"Build footprint & performance improvements:
- Reduce memory usage with CONFIG_DEBUG_INFO=y
In the worst case of an allyesconfig+CONFIG_DEBUG_INFO=y kernel,
DWARF creates almost 200 million relocations, ballooning objtool's
peak heap usage to 53GB. These patches reduce that to 25GB.
On a distro-type kernel with kernel IBT enabled, they reduce
objtool's peak heap usage from 4.2GB to 2.8GB.
These changes also improve the runtime significantly.
Debuggability improvements:
- Add the unwind_debug command-line option, for more extend unwinding
debugging output
- Limit unreachable warnings to once per function
- Add verbose option for disassembling affected functions
- Include backtrace in verbose mode
- Detect missing __noreturn annotations
- Ignore exc_double_fault() __noreturn warnings
- Remove superfluous global_noreturns entries
- Move noreturn function list to separate file
- Add __kunit_abort() to noreturns
Unwinder improvements:
- Allow stack operations in UNWIND_HINT_UNDEFINED regions
- drm/vmwgfx: Add unwind hints around RBP clobber
Cleanups:
- Move the x86 entry thunk restore code into thunk functions
- x86/unwind/orc: Use swap() instead of open coding it
- Remove unnecessary/unused variables
Fixes for modern stack canary handling"
* tag 'objtool-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (42 commits)
x86/orc: Make the is_callthunk() definition depend on CONFIG_BPF_JIT=y
objtool: Skip reading DWARF section data
objtool: Free insns when done
objtool: Get rid of reloc->rel[a]
objtool: Shrink elf hash nodes
objtool: Shrink reloc->sym_reloc_entry
objtool: Get rid of reloc->jump_table_start
objtool: Get rid of reloc->addend
objtool: Get rid of reloc->type
objtool: Get rid of reloc->offset
objtool: Get rid of reloc->idx
objtool: Get rid of reloc->list
objtool: Allocate relocs in advance for new rela sections
objtool: Add for_each_reloc()
objtool: Don't free memory in elf_close()
objtool: Keep GElf_Rel[a] structs synced
objtool: Add elf_create_section_pair()
objtool: Add mark_sec_changed()
objtool: Fix reloc_hash size
objtool: Consolidate rel/rela handling
...
Pull x86 mtrr updates from Borislav Petkov:
"A serious scrubbing of the MTRR code including adding a new map
mechanism in order to look up the memory type of a region easily.
Also address memory range lookup issues like returning an invalid
memory type. Furthermore, this handles the decoupling of PAT from MTRR
more naturally.
All work by Juergen Gross"
* tag 'x86_mtrr_for_v6.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/xen: Set default memory type for PV guests to WB
x86/mtrr: Unify debugging printing
x86/mtrr: Remove unused code
x86/mm: Only check uniform after calling mtrr_type_lookup()
x86/mtrr: Don't let mtrr_type_lookup() return MTRR_TYPE_INVALID
x86/mtrr: Use new cache_map in mtrr_type_lookup()
x86/mtrr: Add mtrr=debug command line option
x86/mtrr: Construct a memory map with cache modes
x86/mtrr: Add get_effective_type() service function
x86/mtrr: Allocate mtrr_value array dynamically
x86/mtrr: Move 32-bit code from mtrr.c to legacy.c
x86/mtrr: Have only one set_mtrr() variant
x86/mtrr: Replace vendor tests in MTRR code
x86/xen: Set MTRR state when running as Xen PV initial domain
x86/hyperv: Set MTRR state when running as SEV-SNP Hyper-V guest
x86/mtrr: Support setting MTRR state for software defined MTRRs
x86/mtrr: Replace size_or_mask and size_and_mask with a much easier concept
x86/mtrr: Remove physical address size calculation
Pull documentation updates from Jonathan Corbet:
"It's been a relatively calm cycle in docsland. We do have:
- Some initial page-table documentation from Linus (the other Linus)
- Regression-handling documentation improvements from Thorsten
- Addition of kerneldoc documentation for the ERR_PTR() and related
macros from James Seo
... and the usual collection of fixes and updates"
* tag 'docs-6.5' of git://git.lwn.net/linux:
docs: consolidate storage interfaces
Documentation: update git configuration for Link: tag
Documentation: KVM: make corrections to vcpu-requests.rst
Documentation: KVM: make corrections to ppc-pv.rst
Documentation: KVM: make corrections to locking.rst
Documentation: KVM: make corrections to halt-polling.rst
Documentation: virt: correct location of haltpoll module params
Documentation/mm: Initial page table documentation
docs: crypto: async-tx-api: fix typo in struct name
docs/doc-guide: Clarify how to write tables
docs: handling-regressions: rework section about fixing procedures
docs: process: fix a typoed cross-reference
docs: submitting-patches: Discuss interleaved replies
MAINTAINERS: direct process doc changes to a dedicated ML
Documentation: core-api: Add error pointer functions to kernel-api
err.h: Add missing kerneldocs for error pointer functions
Documentation: conf.py: Add __force to c_id_attributes
docs: clarify KVM related kernel parameters' descriptions
docs: consolidate human interface subsystems
docs: admin-guide: Add information about intel_pstate active mode
Pull RCU updates from Paul McKenney:
"Documentation updates
Miscellaneous fixes, perhaps most notably:
- Remove RCU_NONIDLE(). The new visibility of most of the idle loop
to RCU has obsoleted this API.
- Make the RCU_SOFTIRQ callback-invocation time limit also apply to
the rcuc kthreads that invoke callbacks for CONFIG_PREEMPT_RT.
- Add a jiffies-based callback-invocation time limit to handle
long-running callbacks. (The local_clock() function is only invoked
once per 32 callbacks due to its high overhead.)
- Stop rcu_tasks_invoke_cbs() from using never-onlined CPUs, which
fixes a bug that can occur on systems with non-contiguous CPU
numbering.
kvfree_rcu updates:
- Eliminate the single-argument variant of k[v]free_rcu() now that
all uses have been converted to k[v]free_rcu_mightsleep().
- Add WARN_ON_ONCE() checks for k[v]free_rcu*() freeing callbacks too
soon. Yes, this is closing the barn door after the horse has
escaped, but Murphy says that there will be more horses.
Callback-offloading updates:
- Fix a number of bugs involving the shrinker and lazy callbacks.
Tasks RCU updates
Torture-test updates"
* tag 'rcu.2023.06.22a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: (32 commits)
torture: Remove duplicated argument -enable-kvm for ppc64
doc/rcutorture: Add description of rcutorture.stall_cpu_block
rcu/rcuscale: Stop kfree_scale_thread thread(s) after unloading rcuscale
rcu/rcuscale: Move rcu_scale_*() after kfree_scale_cleanup()
rcutorture: Correct name of use_softirq module parameter
locktorture: Add long_hold to adjust lock-hold delays
rcu/nocb: Make shrinker iterate only over NOCB CPUs
rcu-tasks: Stop rcu_tasks_invoke_cbs() from using never-onlined CPUs
rcu: Make rcu_cpu_starting() rely on interrupts being disabled
rcu: Mark rcu_cpu_kthread() accesses to ->rcu_cpu_has_work
rcu: Mark additional concurrent load from ->cpu_no_qs.b.exp
rcu: Employ jiffies-based backstop to callback time limit
rcu: Check callback-invocation time limit for rcuc kthreads
rcu: Remove RCU_NONIDLE()
rcu: Add more RCU files to kernel-api.rst
rcu-tasks: Clarify the cblist_init_generic() function's pr_info() output
rcu-tasks: Avoid pr_info() with spin lock in cblist_init_generic()
rcu/nocb: Recheck lazy callbacks under the ->nocb_lock from shrinker
rcu/nocb: Fix shrinker race against callback enqueuer
rcu/nocb: Protect lazy shrinker against concurrent (de-)offloading
...
Pull arm64 updates from Catalin Marinas:
"Notable features are user-space support for the memcpy/memset
instructions and the permission indirection extension.
- Support for the Armv8.9 Permission Indirection Extensions. While
this feature doesn't add new functionality, it enables future
support for Guarded Control Stacks (GCS) and Permission Overlays
- User-space support for the Armv8.8 memcpy/memset instructions
- arm64 perf: support the HiSilicon SoC uncore PMU, Arm CMN sysfs
identifier, support for the NXP i.MX9 SoC DDRC PMU, fixes and
cleanups
- Removal of superfluous ISBs on context switch (following
retrospective architecture tightening)
- Decode the ISS2 register during faults for additional information
to help with debugging
- KPTI clean-up/simplification of the trampoline exit code
- Addressing several -Wmissing-prototype warnings
- Kselftest improvements for signal handling and ptrace
- Fix TPIDR2_EL0 restoring on sigreturn
- Clean-up, robustness improvements of the module allocation code
- More sysreg conversions to the automatic register/bitfields
generation
- CPU capabilities handling cleanup
- Arm documentation updates: ACPI, ptdump"
* tag 'arm64-upstream' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: (124 commits)
kselftest/arm64: Add a test case for TPIDR2 restore
arm64/signal: Restore TPIDR2 register rather than memory state
arm64: alternatives: make clean_dcache_range_nopatch() noinstr-safe
Documentation/arm64: Add ptdump documentation
arm64: hibernate: remove WARN_ON in save_processor_state
kselftest/arm64: Log signal code and address for unexpected signals
docs: perf: Fix warning from 'make htmldocs' in hisi-pmu.rst
arm64/fpsimd: Exit streaming mode when flushing tasks
docs: perf: Add new description for HiSilicon UC PMU
drivers/perf: hisi: Add support for HiSilicon UC PMU driver
drivers/perf: hisi: Add support for HiSilicon H60PA and PAv3 PMU driver
perf: arm_cspmu: Add missing MODULE_DEVICE_TABLE
perf/arm-cmn: Add sysfs identifier
perf/arm-cmn: Revamp model detection
perf/arm_dmc620: Add cpumask
arm64: mm: fix VA-range sanity check
arm64/mm: remove now-superfluous ISBs from TTBR writes
Documentation/arm64: Update ACPI tables from BBR
Documentation/arm64: Update references in arm-acpi
Documentation/arm64: Update ARM and arch reference
...
Pull SMP updates from Thomas Gleixner:
"A large update for SMP management:
- Parallel CPU bringup
The reason why people are interested in parallel bringup is to
shorten the (kexec) reboot time of cloud servers to reduce the
downtime of the VM tenants.
The current fully serialized bringup does the following per AP:
1) Prepare callbacks (allocate, intialize, create threads)
2) Kick the AP alive (e.g. INIT/SIPI on x86)
3) Wait for the AP to report alive state
4) Let the AP continue through the atomic bringup
5) Let the AP run the threaded bringup to full online state
There are two significant delays:
#3 The time for an AP to report alive state in start_secondary()
on x86 has been measured in the range between 350us and 3.5ms
depending on vendor and CPU type, BIOS microcode size etc.
#4 The atomic bringup does the microcode update. This has been
measured to take up to ~8ms on the primary threads depending
on the microcode patch size to apply.
On a two socket SKL server with 56 cores (112 threads) the boot CPU
spends on current mainline about 800ms busy waiting for the APs to
come up and apply microcode. That's more than 80% of the actual
onlining procedure.
This can be reduced significantly by splitting the bringup
mechanism into two parts:
1) Run the prepare callbacks and kick the AP alive for each AP
which needs to be brought up.
The APs wake up, do their firmware initialization and run the
low level kernel startup code including microcode loading in
parallel up to the first synchronization point. (#1 and #2
above)
2) Run the rest of the bringup code strictly serialized per CPU
(#3 - #5 above) as it's done today.
Parallelizing that stage of the CPU bringup might be possible
in theory, but it's questionable whether required surgery
would be justified for a pretty small gain.
If the system is large enough the first AP is already waiting at
the first synchronization point when the boot CPU finished the
wake-up of the last AP. That reduces the AP bringup time on that
SKL from ~800ms to ~80ms, i.e. by a factor ~10x.
The actual gain varies wildly depending on the system, CPU,
microcode patch size and other factors. There are some
opportunities to reduce the overhead further, but that needs some
deep surgery in the x86 CPU bringup code.
For now this is only enabled on x86, but the core functionality
obviously works for all SMP capable architectures.
- Enhancements for SMP function call tracing so it is possible to
locate the scheduling and the actual execution points. That allows
to measure IPI delivery time precisely"
* tag 'smp-core-2023-06-26' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/tip/tip: (45 commits)
trace,smp: Add tracepoints for scheduling remotelly called functions
trace,smp: Add tracepoints around remotelly called functions
MAINTAINERS: Add CPU HOTPLUG entry
x86/smpboot: Fix the parallel bringup decision
x86/realmode: Make stack lock work in trampoline_compat()
x86/smp: Initialize cpu_primary_thread_mask late
cpu/hotplug: Fix off by one in cpuhp_bringup_mask()
x86/apic: Fix use of X{,2}APIC_ENABLE in asm with older binutils
x86/smpboot/64: Implement arch_cpuhp_init_parallel_bringup() and enable it
x86/smpboot: Support parallel startup of secondary CPUs
x86/smpboot: Implement a bit spinlock to protect the realmode stack
x86/apic: Save the APIC virtual base address
cpu/hotplug: Allow "parallel" bringup up to CPUHP_BP_KICK_AP_STATE
x86/apic: Provide cpu_primary_thread mask
x86/smpboot: Enable split CPU startup
cpu/hotplug: Provide a split up CPUHP_BRINGUP mechanism
cpu/hotplug: Reset task stack state in _cpu_up()
cpu/hotplug: Remove unused state functions
riscv: Switch to hotplug core state synchronization
parisc: Switch to hotplug core state synchronization
...
Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy. Move
Documentation/arm64 into arch/ (along with the Chinese equvalent
translations) and fix up documentation references.
Cc: Will Deacon <will@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <src.res@email.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Yantengsi <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
An Interrupt Remapping Table (IRT) stores interrupt remapping configuration
for each device. In a normal operation, the AMD IOMMU caches the table
to optimize subsequent data accesses. This requires the IOMMU driver to
invalidate IRT whenever it updates the table. The invalidation process
includes issuing an INVALIDATE_INTERRUPT_TABLE command following by
a COMPLETION_WAIT command.
However, there are cases in which the IRT is updated at a high rate.
For example, for IOMMU AVIC, the IRTE[IsRun] bit is updated on every
vcpu scheduling (i.e. amd_iommu_update_ga()). On system with large
amount of vcpus and VFIO PCI pass-through devices, the invalidation
process could potentially become a performance bottleneck.
Introducing a new kernel boot option:
amd_iommu=irtcachedis
which disables IRTE caching by setting the IRTCachedis bit in each IOMMU
Control register, and bypass the IRT invalidation process.
Reviewed-by: Jerry Snitselaar <jsnitsel@redhat.com>
Co-developed-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Alejandro Jimenez <alejandro.j.jimenez@oracle.com>
Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Link: https://lore.kernel.org/r/20230530141137.14376-4-suravee.suthikulpanit@amd.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Provide a generic smt parameters interface aligned with s390
to allow users to limit smt usage and threads per core.
It replaced previous undocumented "nothreads" parameter for
smp-cps which is ambiguous and does not cover smp-mt.
Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
name_to_dev_t has a very misleading name, that doesn't make clear
it should only be used by the early init code, and also has a bad
calling convention that doesn't allow returning different kinds of
errors. Rename it to early_lookup_bdev to make the use case clear,
and return an errno, where -EINVAL means the string could not be
parsed, and -ENODEV means it the string was valid, but there was
no device found for it.
Also stub out the whole call for !CONFIG_BLOCK as all the non-block
root cases are always covered in the caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230531125535.676098-14-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
The descriptions of certain KVM related kernel parameters can be
confusing. They state "Disable ...," which may make people think that
setting them to 1 will disable the associated feature when in fact the
opposite is true.
This commit addresses this issue by revising the descriptions of these
parameters by using "Control..." rather than "Enable/Disable...".
1==enabled or 0==disabled can be communicated by the description of
default value such as "1 (enabled)" or "0 (disabled)".
Also update the description of KVM's default value for kvm-intel.nested
as it is enabled by default.
Signed-off-by: Yan-Jie Wang <yanjiewtw@gmail.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20230503081530.19956-1-yanjiewtw@gmail.com
Information about intel_pstate active mode is added in the doc.
This operation mode could be used to set on the hardware when it's
not activated. Status of the mode could be checked from sysfs file
i.e., /sys/devices/system/cpu/intel_pstate/status.
The information is already available in cpu-freq/intel-pstate.txt
documentation.
Signed-off-by: Natesh Sharma <nsharma@redhat.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
[jc: reformatted for width ]
Link: https://lore.kernel.org/r/20230427083706.49882-1-nsharma@redhat.com
Workqueue now automatically marks per-cpu work items that hog CPU for too
long as CPU_INTENSIVE, which excludes them from concurrency management and
prevents stalling other concurrency-managed work items. If a work function
keeps running over the thershold, it likely needs to be switched to use an
unbound workqueue.
This patch adds a debug mechanism which tracks the work functions which
trigger the automatic CPU_INTENSIVE mechanism and report them using
pr_warn() with exponential backoff.
v3: Documentation update.
v2: Drop bouncing to kthread_worker for printing messages. It was to avoid
introducing circular locking dependency through printk but not effective
as it still had pool lock -> wci_lock -> printk -> pool lock loop. Let's
just print directly using printk_deferred().
Signed-off-by: Tejun Heo <tj@kernel.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
