The main CPUID header <asm/cpuid.h> was originally a storefront for the
headers:
<asm/cpuid/api.h>
<asm/cpuid/leaf_0x2_api.h>
Now that the latter CPUID(0x2) header has been merged into the former,
there is no practical difference between <asm/cpuid.h> and
<asm/cpuid/api.h>.
Migrate all users to the <asm/cpuid/api.h> header, in preparation of
the removal of <asm/cpuid.h>.
Don't remove <asm/cpuid.h> just yet, in case some new code in -next
started using it.
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: x86-cpuid@lists.linux.dev
Link: https://lore.kernel.org/r/20250508150240.172915-3-darwi@linutronix.de
For historic reasons there are some TSC-related functions in the
<asm/msr.h> header, even though there's an <asm/tsc.h> header.
To facilitate the relocation of rdtsc{,_ordered}() from <asm/msr.h>
to <asm/tsc.h> and to eventually eliminate the inclusion of
<asm/msr.h> in <asm/tsc.h>, add an explicit <asm/msr.h> dependency
to the source files that reference definitions from <asm/msr.h>.
[ mingo: Clarified the changelog. ]
Signed-off-by: Xin Li (Intel) <xin@zytor.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Uros Bizjak <ubizjak@gmail.com>
Link: https://lore.kernel.org/r/20250501054241.1245648-1-xin@zytor.com
TSC could be reset in deep ACPI sleep states, even with invariant TSC.
That's the reason we have sched_clock() save/restore functions, to deal
with this situation. But what happens is that such functions are guarded
with a check for the stability of sched_clock - if not considered stable,
the save/restore routines aren't executed.
On top of that, we have a clear comment in native_sched_clock() saying
that *even* with TSC unstable, we continue using TSC for sched_clock due
to its speed.
In other words, if we have a situation of TSC getting detected as unstable,
it marks the sched_clock as unstable as well, so subsequent S3 sleep cycles
could bring bogus sched_clock values due to the lack of the save/restore
mechanism, causing warnings like this:
[22.954918] ------------[ cut here ]------------
[22.954923] Delta way too big! 18446743750843854390 ts=18446744072977390405 before=322133536015 after=322133536015 write stamp=18446744072977390405
[22.954923] If you just came from a suspend/resume,
[22.954923] please switch to the trace global clock:
[22.954923] echo global > /sys/kernel/tracing/trace_clock
[22.954923] or add trace_clock=global to the kernel command line
[22.954937] WARNING: CPU: 2 PID: 5728 at kernel/trace/ring_buffer.c:2890 rb_add_timestamp+0x193/0x1c0
Notice that the above was reproduced even with "trace_clock=global".
The fix for that is to _always_ save/restore the sched_clock on suspend
cycle _if TSC is used_ as sched_clock - only if we fallback to jiffies
the sched_clock_stable() check becomes relevant to save/restore the
sched_clock.
Debugged-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: stable@vger.kernel.org
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20250215210314.351480-1-gpiccoli@igalia.com
use the generic struct x86_cpu_id thing
- Remove magic naked numbers for CPUID functions and use proper defines of the
prefix CPUID_LEAF_*. Consolidate some of the crazy use around the tree
- Smaller cleanups and improvements
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Merge tag 'x86_cpu_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpuid updates from Borislav Petkov:
- Remove the less generic CPU matching infra around struct x86_cpu_desc
and use the generic struct x86_cpu_id thing
- Remove magic naked numbers for CPUID functions and use proper defines
of the prefix CPUID_LEAF_*. Consolidate some of the crazy use around
the tree
- Smaller cleanups and improvements
* tag 'x86_cpu_for_v6.14_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/cpu: Make all all CPUID leaf names consistent
x86/fpu: Remove unnecessary CPUID level check
x86/fpu: Move CPUID leaf definitions to common code
x86/tsc: Remove CPUID "frequency" leaf magic numbers.
x86/tsc: Move away from TSC leaf magic numbers
x86/cpu: Move TSC CPUID leaf definition
x86/cpu: Refresh DCA leaf reading code
x86/cpu: Remove unnecessary MwAIT leaf checks
x86/cpu: Use MWAIT leaf definition
x86/cpu: Move MWAIT leaf definition to common header
x86/cpu: Remove 'x86_cpu_desc' infrastructure
x86/cpu: Move AMD erratum 1386 table over to 'x86_cpu_id'
x86/cpu: Replace PEBS use of 'x86_cpu_desc' use with 'x86_cpu_id'
x86/cpu: Expose only stepping min/max interface
x86/cpu: Introduce new microcode matching helper
x86/cpufeature: Document cpu_feature_enabled() as the default to use
x86/paravirt: Remove the WBINVD callback
x86/cpufeatures: Free up unused feature bits
Use the GUEST_TSC_FREQ MSR to discover the TSC frequency instead of
relying on kvm-clock based frequency calibration. Override both CPU and
TSC frequency calibration callbacks with securetsc_get_tsc_khz(). Since
the difference between CPU base and TSC frequency does not apply in this
case, the same callback is being used.
[ bp: Carve out from
https://lore.kernel.org/r/20250106124633.1418972-11-nikunj@amd.com ]
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250106124633.1418972-11-nikunj@amd.com
Switch all instrumentable users of the seqcount_latch interface over to
the non-raw interface.
Co-developed-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20241104161910.780003-5-elver@google.com
The unsynchronized_tsc() eventually checks num_possible_cpus(), and if the
system is non-Intel and the number of possible CPUs is greater than one,
assumes that TSCs are unsynchronized. This despite the comment saying
"assume multi socket systems are not synchronized", that is, socket rather
than CPU. This behavior was preserved by commit 8fbbc4b45c ("x86: merge
tsc_init and clocksource code") and by the previous relevant commit
7e69f2b1ea ("clocksource: Remove the update callback").
The clocksource drivers were added by commit 5d0cf410e9 ("Time: i386
Clocksource Drivers") back in 2006, and the comment still said "socket"
rather than "CPU".
Therefore, bravely (and perhaps foolishly) make the code match the
comment.
Note that it is possible to bypass both code and comment by booting
with tsc=reliable, but this also disables the clocksource watchdog,
which is undesirable when trust in the TSC is strictly limited.
Reported-by: Zhengxu Chen <zhxchen17@meta.com>
Reported-by: Danielle Costantino <dcostantino@meta.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20240802154618.4149953-5-paulmck@kernel.org
Commit b50db7095f ("x86/tsc: Disable clocksource watchdog for TSC on
qualified platorms") was introduced to solve problem that sometimes TSC
clocksource is wrongly judged as unstable by watchdog like 'jiffies', HPET,
etc.
In it, the hardware package number is a key factor for judging whether to
disable the watchdog for TSC, and 'nr_online_nodes' was chosen due to, at
that time (kernel v5.1x), it is available in early boot phase before
registering 'tsc-early' clocksource, where all non-boot CPUs are not
brought up yet.
Dave and Rui pointed out there are many cases in which 'nr_online_nodes'
is cheated and not accurate, like:
* SNC (sub-numa cluster) mode enabled
* numa emulation (numa=fake=8 etc.)
* numa=off
* platforms with CPU-less HBM nodes, CPU-less Optane memory nodes.
* 'maxcpus=' cmdline setup, where chopped CPUs could be onlined later
* 'nr_cpus=', 'possible_cpus=' cmdline setup, where chopped CPUs can
not be onlined after boot
The SNC case is the most user-visible case, as many CSP (Cloud Service
Provider) enable this feature in their server fleets. When SNC3 enabled, a
2 socket machine will appear to have 6 NUMA nodes, and get impacted by the
issue in reality.
Thomas' recent patchset of refactoring x86 topology code improves
topology_max_packages() greatly, by making it more accurate and available
in early boot phase, which works well in most of the above cases.
The only exceptions are 'nr_cpus=' and 'possible_cpus=' setup, which may
under-estimate the package number. As during topology setup, the boot CPU
iterates through all enumerated APIC IDs and either accepts or rejects the
APIC ID. For accepted IDs, it figures out which bits of the ID map to the
package number. It tracks which package numbers have been seen in a
bitmap. topology_max_packages() just returns the number of bits set in
that bitmap.
'nr_cpus=' and 'possible_cpus=' can cause more APIC IDs to be rejected and
can artificially lower the number of bits in the package bitmap and thus
topology_max_packages(). This means that, for example, a system with 8
physical packages might reject all the CPUs on 6 of those packages and be
left with only 2 packages and 2 bits set in the package bitmap. It needs
the TSC watchdog, but would disable it anyway. This isn't ideal, but it
only happens for debug-oriented options. This is fixable by tracking the
package numbers for rejected CPUs. But it's not worth the trouble for
debugging.
So use topology_max_packages() to replace nr_online_nodes().
Reported-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/all/20240729021202.180955-1-feng.tang@intel.com
Closes: https://lore.kernel.org/lkml/a4860054-0f16-6513-f121-501048431086@intel.com/
convert_art_to_tsc() and convert_art_ns_to_tsc() interfaces are no
longer required. The conversion is now handled by the core code.
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240513103813.5666-9-lakshmi.sowjanya.d@intel.com
The core code provides a new mechanism to allow conversion between ART and
TSC. This allows to replace the x86 specific ART/TSC conversion functions.
Prepare for removal by filling in the base clock conversion information for
ART and associating the base clock to the TSC clocksource.
The existing conversion functions will be removed once the usage sites are
converted over to the new model.
[ tglx: Massaged change log ]
Co-developed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Co-developed-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
Signed-off-by: Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240513103813.5666-3-lakshmi.sowjanya.d@intel.com
- Rework the x86 CPU vendor/family/model code: introduce the 'VFM'
value that is an 8+8+8 bit concatenation of the vendor/family/model
value, and add macros that work on VFM values. This simplifies the
addition of new Intel models & families, and simplifies existing
enumeration & quirk code.
- Add support for the AMD 0x80000026 leaf, to better parse topology
information.
- Optimize the NUMA allocation layout of more per-CPU data structures
- Improve the workaround for AMD erratum 1386
- Clear TME from /proc/cpuinfo as well, when disabled by the firmware
- Improve x86 self-tests
- Extend the mce_record tracepoint with the ::ppin and ::microcode fields
- Implement recovery for MCE errors in TDX/SEAM non-root mode
- Misc cleanups and fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 cpu updates from Ingo Molnar:
- Rework the x86 CPU vendor/family/model code: introduce the 'VFM'
value that is an 8+8+8 bit concatenation of the vendor/family/model
value, and add macros that work on VFM values. This simplifies the
addition of new Intel models & families, and simplifies existing
enumeration & quirk code.
- Add support for the AMD 0x80000026 leaf, to better parse topology
information
- Optimize the NUMA allocation layout of more per-CPU data structures
- Improve the workaround for AMD erratum 1386
- Clear TME from /proc/cpuinfo as well, when disabled by the firmware
- Improve x86 self-tests
- Extend the mce_record tracepoint with the ::ppin and ::microcode fields
- Implement recovery for MCE errors in TDX/SEAM non-root mode
- Misc cleanups and fixes
* tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits)
x86/mm: Switch to new Intel CPU model defines
x86/tsc_msr: Switch to new Intel CPU model defines
x86/tsc: Switch to new Intel CPU model defines
x86/cpu: Switch to new Intel CPU model defines
x86/resctrl: Switch to new Intel CPU model defines
x86/microcode/intel: Switch to new Intel CPU model defines
x86/mce: Switch to new Intel CPU model defines
x86/cpu: Switch to new Intel CPU model defines
x86/cpu/intel_epb: Switch to new Intel CPU model defines
x86/aperfmperf: Switch to new Intel CPU model defines
x86/apic: Switch to new Intel CPU model defines
perf/x86/msr: Switch to new Intel CPU model defines
perf/x86/intel/uncore: Switch to new Intel CPU model defines
perf/x86/intel/pt: Switch to new Intel CPU model defines
perf/x86/lbr: Switch to new Intel CPU model defines
perf/x86/intel/cstate: Switch to new Intel CPU model defines
x86/bugs: Switch to new Intel CPU model defines
x86/bugs: Switch to new Intel CPU model defines
x86/cpu/vfm: Update arch/x86/include/asm/intel-family.h
x86/cpu/vfm: Add new macros to work with (vendor/family/model) values
...
New CPU #defines encode vendor and family as well as model.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/all/20240424181517.41907-1-tony.luck%40intel.com
__use_tsc is only ever enabled in __init tsc_enable_sched_clock(), so mark
it as __ro_after_init.
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/20240313180106.2917308-5-vschneid@redhat.com
The clocksource pointer in struct system_counterval_t is not evaluated any
more. Remove the code setting the member, and the member itself.
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240201010453.2212371-8-peter.hilber@opensynergy.com
Add a clocksource ID for TSC and a distinct one for the early TSC.
Use distinct IDs for TSC and early TSC, since those also have distinct
clocksource structs. This should help to keep existing semantics when
comparing clocksources.
Also, set the recently added struct system_counterval_t member cs_id to the
TSC ID in the cases where the clocksource member is being set to the TSC
clocksource. In the future, get_device_system_crosststamp() will compare
the clocksource ID in struct system_counterval_t, rather than the
clocksource.
For the x86 ART related code, system_counterval_t.cs == NULL corresponds to
system_counterval_t.cs_id == CSID_GENERIC (0).
Signed-off-by: Peter Hilber <peter.hilber@opensynergy.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240201010453.2212371-4-peter.hilber@opensynergy.com
Add or modify function descriptions to remove kernel-doc warnings:
tsc.c:655: warning: missing initial short description on line:
* native_calibrate_tsc
tsc.c:1339: warning: Excess function parameter 'cycles' description in 'convert_art_ns_to_tsc'
tsc.c:1339: warning: Excess function parameter 'cs' description in 'convert_art_ns_to_tsc'
tsc.c:1373: warning: Function parameter or member 'work' not described in 'tsc_refine_calibration_work'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20231221033620.32379-1-rdunlap@infradead.org
There were reports again that the tsc clocksource on 4 sockets x86
servers was wrongly judged as 'unstable' by 'jiffies' and other
watchdogs, and disabled [1][2].
Commit b50db7095f ("x86/tsc: Disable clocksource watchdog for TSC
on qualified platorms") was introduce to deal with these false
alarms of tsc unstable issues, covering qualified platforms for 2
sockets or smaller ones. And from history of chasing TSC issues,
Thomas and Peter only saw real TSC synchronization issue on 8 socket
machines.
So extend the exemption to 4 sockets to fix the issue.
Rui also proposed another way to disable 'jiffies' as clocksource
watchdog [3], which can also solve problem in [1]. in an architecture
independent way, but can't cure the problem in [2]. whose watchdog
is HPET or PMTIMER, while 'jiffies' is mostly used as watchdog in
boot phase.
'nr_online_nodes' has known inaccurate problem for cases like
platform with cpu-less memory nodes, sub numa cluster enabled,
fakenuma, kernel cmdline parameter 'maxcpus=', etc. The harmful case
is the 'maxcpus' one which could possibly under estimates the package
number, and disable the watchdog, but bright side is it is mostly
for debug usage. All these will be addressed in other patches, as
discussed in thread [4].
[1]. https://lore.kernel.org/all/9d3bf570-3108-0336-9c52-9bee15767d29@huawei.com/
[2]. https://lore.kernel.org/lkml/06df410c-2177-4671-832f-339cff05b1d9@paulmck-laptop/
[3]. https://lore.kernel.org/all/bd5b97f89ab2887543fc262348d1c7cafcaae536.camel@intel.com/
[4]. https://lore.kernel.org/all/20221021062131.1826810-1-feng.tang@intel.com/
Reported-by: Yu Liao <liaoyu15@huawei.com>
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Scheduler SMP load-balancer improvements:
- Avoid unnecessary migrations within SMT domains on hybrid systems.
Problem:
On hybrid CPU systems, (processors with a mixture of higher-frequency
SMT cores and lower-frequency non-SMT cores), under the old code
lower-priority CPUs pulled tasks from the higher-priority cores if
more than one SMT sibling was busy - resulting in many unnecessary
task migrations.
Solution:
The new code improves the load balancer to recognize SMT cores with more
than one busy sibling and allows lower-priority CPUs to pull tasks, which
avoids superfluous migrations and lets lower-priority cores inspect all SMT
siblings for the busiest queue.
- Implement the 'runnable boosting' feature in the EAS balancer: consider CPU
contention in frequency, EAS max util & load-balance busiest CPU selection.
This improves CPU utilization for certain workloads, while leaves other key
workloads unchanged.
- Scheduler infrastructure improvements:
- Rewrite the scheduler topology setup code by consolidating it
into the build_sched_topology() helper function and building
it dynamically on the fly.
- Resolve the local_clock() vs. noinstr complications by rewriting
the code: provide separate sched_clock_noinstr() and
local_clock_noinstr() functions to be used in instrumentation code,
and make sure it is all instrumentation-safe.
- Fixes:
- Fix a kthread_park() race with wait_woken()
- Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
- Fix UP PREEMPT bug by unifying the SMP and UP implementations.
- Fix task_struct::saved_state handling.
- Fix various rq clock update bugs, unearthed by turning on the rq clock
debugging code.
- Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger by
creating enough cgroups, by removing the warnign and restricting
window size triggers to PSI file write-permission or CAP_SYS_RESOURCE.
- Propagate SMT flags in the topology when removing degenerate domain
- Fix grub_reclaim() calculation bug in the deadline scheduler code
- Avoid resetting the min update period when it is unnecessary, in
psi_trigger_destroy().
- Don't balance a task to its current running CPU in load_balance(),
which was possible on certain NUMA topologies with overlapping
groups.
- Fix the sched-debug printing of rq->nr_uninterruptible
- Cleanups:
- Address various -Wmissing-prototype warnings, as a preparation
to (maybe) enable this warning in the future.
- Remove unused code
- Mark more functions __init
- Fix shadow-variable warnings
Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler updates from Ingo Molnar:
"Scheduler SMP load-balancer improvements:
- Avoid unnecessary migrations within SMT domains on hybrid systems.
Problem:
On hybrid CPU systems, (processors with a mixture of
higher-frequency SMT cores and lower-frequency non-SMT cores),
under the old code lower-priority CPUs pulled tasks from the
higher-priority cores if more than one SMT sibling was busy -
resulting in many unnecessary task migrations.
Solution:
The new code improves the load balancer to recognize SMT cores
with more than one busy sibling and allows lower-priority CPUs
to pull tasks, which avoids superfluous migrations and lets
lower-priority cores inspect all SMT siblings for the busiest
queue.
- Implement the 'runnable boosting' feature in the EAS balancer:
consider CPU contention in frequency, EAS max util & load-balance
busiest CPU selection.
This improves CPU utilization for certain workloads, while leaves
other key workloads unchanged.
Scheduler infrastructure improvements:
- Rewrite the scheduler topology setup code by consolidating it into
the build_sched_topology() helper function and building it
dynamically on the fly.
- Resolve the local_clock() vs. noinstr complications by rewriting
the code: provide separate sched_clock_noinstr() and
local_clock_noinstr() functions to be used in instrumentation code,
and make sure it is all instrumentation-safe.
Fixes:
- Fix a kthread_park() race with wait_woken()
- Fix misc wait_task_inactive() bugs unearthed by the -rt merge:
- Fix UP PREEMPT bug by unifying the SMP and UP implementations
- Fix task_struct::saved_state handling
- Fix various rq clock update bugs, unearthed by turning on the rq
clock debugging code.
- Fix the PSI WINDOW_MIN_US trigger limit, which was easy to trigger
by creating enough cgroups, by removing the warnign and restricting
window size triggers to PSI file write-permission or
CAP_SYS_RESOURCE.
- Propagate SMT flags in the topology when removing degenerate domain
- Fix grub_reclaim() calculation bug in the deadline scheduler code
- Avoid resetting the min update period when it is unnecessary, in
psi_trigger_destroy().
- Don't balance a task to its current running CPU in load_balance(),
which was possible on certain NUMA topologies with overlapping
groups.
- Fix the sched-debug printing of rq->nr_uninterruptible
Cleanups:
- Address various -Wmissing-prototype warnings, as a preparation to
(maybe) enable this warning in the future.
- Remove unused code
- Mark more functions __init
- Fix shadow-variable warnings"
* tag 'sched-core-2023-06-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (50 commits)
sched/core: Avoid multiple calling update_rq_clock() in __cfsb_csd_unthrottle()
sched/core: Avoid double calling update_rq_clock() in __balance_push_cpu_stop()
sched/core: Fixed missing rq clock update before calling set_rq_offline()
sched/deadline: Update GRUB description in the documentation
sched/deadline: Fix bandwidth reclaim equation in GRUB
sched/wait: Fix a kthread_park race with wait_woken()
sched/topology: Mark set_sched_topology() __init
sched/fair: Rename variable cpu_util eff_util
arm64/arch_timer: Fix MMIO byteswap
sched/fair, cpufreq: Introduce 'runnable boosting'
sched/fair: Refactor CPU utilization functions
cpuidle: Use local_clock_noinstr()
sched/clock: Provide local_clock_noinstr()
x86/tsc: Provide sched_clock_noinstr()
clocksource: hyper-v: Provide noinstr sched_clock()
clocksource: hyper-v: Adjust hv_read_tsc_page_tsc() to avoid special casing U64_MAX
x86/vdso: Fix gettimeofday masking
math64: Always inline u128 version of mul_u64_u64_shr()
s390/time: Provide sched_clock_noinstr()
loongarch: Provide noinstr sched_clock_read()
...
With the intent to provide local_clock_noinstr(), a variant of
local_clock() that's safe to be called from noinstr code (with the
assumption that any such code will already be non-preemptible),
prepare for things by providing a noinstr sched_clock_noinstr()
function.
Specifically, preempt_enable_*() calls out to schedule(), which upsets
noinstr validation efforts.
vmlinux.o: warning: objtool: native_sched_clock+0x96: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
vmlinux.o: warning: objtool: kvm_clock_read+0x22: call to preempt_schedule_notrace_thunk() leaves .noinstr.text section
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com> # Hyper-V
Link: https://lore.kernel.org/r/20230519102715.910937674@infradead.org
When TSC is synchronized across sockets then there is no reason to
calibrate the delay for the first CPU which comes up on a socket.
Just reuse the existing calibration value.
This removes 100ms pointlessly wasted time from CPU hotplug per socket.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Tested-by: Helge Deller <deller@gmx.de> # parisc
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Link: https://lore.kernel.org/r/20230512205255.608773568@linutronix.de
Core:
- Yet another round of improvements to make the clocksource watchdog
more robust:
- Relax the clocksource-watchdog skew criteria to match the NTP
criteria.
- Temporarily skip the watchdog when high memory latencies are
detected which can lead to false-positives.
- Provide an option to enable TSC skew detection even on systems
where TSC is marked as reliable.
Sigh!
- Initialize the restart block in the nanosleep syscalls to be directed
to the no restart function instead of doing a partial setup on entry.
This prevents an erroneous restart_syscall() invocation from
corrupting user space data. While such a situation is clearly a user
space bug, preventing this is a correctness issue and caters to the
least suprise principle.
- Ignore the hrtimer slack for realtime tasks in schedule_hrtimeout()
to align it with the nanosleep semantics.
Drivers:
- The obligatory new driver bindings for Mediatek, Rockchip and RISC-V
variants.
- Add support for the C3STOP misfeature to the RISC-V timer to handle
the case where the timer stops in deeper idle state.
- Set up a static key in the RISC-V timer correctly before first use.
- The usual small improvements and fixes all over the place
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Merge tag 'timers-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer updates from Thomas Gleixner:
"Updates for timekeeping, timers and clockevent/source drivers:
Core:
- Yet another round of improvements to make the clocksource watchdog
more robust:
- Relax the clocksource-watchdog skew criteria to match the NTP
criteria.
- Temporarily skip the watchdog when high memory latencies are
detected which can lead to false-positives.
- Provide an option to enable TSC skew detection even on systems
where TSC is marked as reliable.
Sigh!
- Initialize the restart block in the nanosleep syscalls to be
directed to the no restart function instead of doing a partial
setup on entry.
This prevents an erroneous restart_syscall() invocation from
corrupting user space data. While such a situation is clearly a
user space bug, preventing this is a correctness issue and caters
to the least suprise principle.
- Ignore the hrtimer slack for realtime tasks in schedule_hrtimeout()
to align it with the nanosleep semantics.
Drivers:
- The obligatory new driver bindings for Mediatek, Rockchip and
RISC-V variants.
- Add support for the C3STOP misfeature to the RISC-V timer to handle
the case where the timer stops in deeper idle state.
- Set up a static key in the RISC-V timer correctly before first use.
- The usual small improvements and fixes all over the place"
* tag 'timers-core-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
clocksource/drivers/timer-sun4i: Add CLOCK_EVT_FEAT_DYNIRQ
clocksource/drivers/em_sti: Mark driver as non-removable
clocksource/drivers/sh_tmu: Mark driver as non-removable
clocksource/drivers/riscv: Patch riscv_clock_next_event() jump before first use
clocksource/drivers/timer-microchip-pit64b: Add delay timer
clocksource/drivers/timer-microchip-pit64b: Select driver only on ARM
dt-bindings: timer: sifive,clint: add comaptibles for T-Head's C9xx
dt-bindings: timer: mediatek,mtk-timer: add MT8365
clocksource/drivers/riscv: Get rid of clocksource_arch_init() callback
clocksource/drivers/sh_cmt: Mark driver as non-removable
clocksource/drivers/timer-microchip-pit64b: Drop obsolete dependency on COMPILE_TEST
clocksource/drivers/riscv: Increase the clock source rating
clocksource/drivers/timer-riscv: Set CLOCK_EVT_FEAT_C3STOP based on DT
dt-bindings: timer: Add bindings for the RISC-V timer device
RISC-V: time: initialize hrtimer based broadcast clock event device
dt-bindings: timer: rk-timer: Add rktimer for rv1126
time/debug: Fix memory leak with using debugfs_lookup()
clocksource: Enable TSC watchdog checking of HPET and PMTMR only when requested
posix-timers: Use atomic64_try_cmpxchg() in __update_gt_cputime()
clocksource: Verify HPET and PMTMR when TSC unverified
...
- Correct the common copy and pasted mishandling of kstrtobool() in the
strict_sas_size() setup function.
- Make recalibrate_cpu_khz() an GPL only export.
- Check TSC feature before doing anything else which avoids pointless
code execution if TSC is not available.
- Remove or fixup stale and misleading comments.
- Remove unused or pointelessly duplicated variables.
- Spelling and typo fixes.
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Merge tag 'x86-cleanups-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull miscellaneous x86 cleanups from Thomas Gleixner:
- Correct the common copy and pasted mishandling of kstrtobool() in the
strict_sas_size() setup function
- Make recalibrate_cpu_khz() an GPL only export
- Check TSC feature before doing anything else which avoids pointless
code execution if TSC is not available
- Remove or fixup stale and misleading comments
- Remove unused or pointelessly duplicated variables
- Spelling and typo fixes
* tag 'x86-cleanups-2023-02-20' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/hotplug: Remove incorrect comment about mwait_play_dead()
x86/tsc: Do feature check as the very first thing
x86/tsc: Make recalibrate_cpu_khz() export GPL only
x86/cacheinfo: Remove unused trace variable
x86/Kconfig: Fix spellos & punctuation
x86/signal: Fix the value returned by strict_sas_size()
x86/cpu: Remove misleading comment
x86/setup: Move duplicate boot_cpu_data definition out of the ifdeffery
x86/boot/e820: Fix typo in e820.c comment
Do the feature check as the very first thing in the function. Everything
else comes after that and is meaningless work if the TSC CPUID bit is
not even set. Switch to cpu_feature_enabled() too, while at it.
No functional changes.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/Y5990CUCuWd5jfBH@zn.tnic
A quick search doesn't reveal any use outside of the kernel - which
would be questionable to begin with anyway - so make the export GPL
only.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/Y599miBzWRAuOwhg@zn.tnic
Unconditionally enabling TSC watchdog checking of the HPET and PMTMR
clocksources can degrade latency and performance. Therefore, provide
a new "watchdog" option to the tsc= boot parameter that opts into such
checking. Note that tsc=watchdog is overridden by a tsc=nowatchdog
regardless of their relative positions in the list of boot parameters.
Reported-by: Thomas Gleixner <tglx@linutronix.de>
Reported-by: Waiman Long <longman@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Waiman Long <longman@redhat.com>
On systems with two or fewer sockets, when the boot CPU has CONSTANT_TSC,
NONSTOP_TSC, and TSC_ADJUST, clocksource watchdog verification of the
TSC is disabled. This works well much of the time, but there is the
occasional production-level system that meets all of these criteria, but
which still has a TSC that skews significantly from atomic-clock time.
This is usually attributed to a firmware or hardware fault. Yes, the
various NTP daemons do express their opinions of userspace-to-atomic-clock
time skew, but they put them in various places, depending on the daemon
and distro in question. It would therefore be good for the kernel to
have some clue that there is a problem.
The old behavior of marking the TSC unstable is a non-starter because a
great many workloads simply cannot tolerate the overheads and latencies
of the various non-TSC clocksources. In addition, NTP-corrected systems
sometimes can tolerate significant kernel-space time skew as long as
the userspace time sources are within epsilon of atomic-clock time.
Therefore, when watchdog verification of TSC is disabled, enable it for
HPET and PMTMR (AKA ACPI PM timer). This provides the needed in-kernel
time-skew diagnostic without degrading the system's performance.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Waiman Long <longman@redhat.com>
Cc: <x86@kernel.org>
Tested-by: Feng Tang <feng.tang@intel.com>
The kernel assumes that the TSC frequency which is provided by the
hardware / firmware via MSRs or CPUID(0x15) is correct after applying
a few basic consistency checks. This disables the TSC recalibration
against HPET or PM timer.
As a result there is no mechanism to validate that frequency in cases
where a firmware or hardware defect is suspected. And there was case
that some user used atomic clock to measure the TSC frequency and
reported an inaccuracy issue, which was later fixed in firmware.
Add an option 'recalibrate' for 'tsc' kernel parameter to force the
tsc freq recalibration with HPET or PM timer, and warn if the
deviation from previous value is more than about 500 PPM, which
provides a way to verify the data from hardware / firmware.
There is no functional change to existing work flow.
Recently there was a real-world case: "The 40ms/s divergence between
TSC and HPET was observed on hardware that is quite recent" [1], on
that platform the TSC frequence 1896 MHz was got from CPUID(0x15),
and the force-reclibration with HPET/PMTIMER both calibrated out
value of 1975 MHz, which also matched with check from software
'chronyd', indicating it's a problem of BIOS or firmware.
[Thanks tglx for helping improving the commit log]
[ paulmck: Wordsmith Kconfig help text. ]
[1]. https://lore.kernel.org/lkml/20221117230910.GI4001@paulmck-ThinkPad-P17-Gen-1/
Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <x86@kernel.org>
Cc: <linux-doc@vger.kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
In order to use sched_clock() from noinstr code, mark it and all it's
implenentations noinstr.
The whole pvclock thing (used by KVM/Xen) is a bit of a pain,
since it calls out to watchdogs, create a
pvclock_clocksource_read_nowd() variant doesn't do that and can be
noinstr.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20230126151323.702003578@infradead.org
The symbol is not used outside of the file, so mark it static.
Fixes the following warning:
arch/x86/kernel/tsc.c:53:20: warning:
symbol 'art_related_clocksource' was not declared. Should it be static?
Signed-off-by: Chen Lifu <chenlifu@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220823021821.3052159-1-chenlifu@huawei.com
Currently loops_per_jiffy is set in tsc_early_init(), but then don't
switch to delay_tsc, with the result that delay_loop is used with
loops_per_jiffy set for delay_tsc.
Then in (late) tsc_init() lpj_fine is set (which is mostly unused) and
after which use_tsc_delay() is finally called.
Move both loops_per_jiffy and use_tsc_delay() into
tsc_enable_sched_clock() which is called the moment tsc_khz is
determined, be it early or late. Keeping the lot consistent.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220304152135.914397165@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are cases that the TSC clocksource is wrongly judged as unstable by
the clocksource watchdog mechanism which tries to validate the TSC against
HPET, PM_TIMER or jiffies. While there is hardly a general reliable way to
check the validity of a watchdog, Thomas Gleixner proposed [1]:
"I'm inclined to lift that requirement when the CPU has:
1) X86_FEATURE_CONSTANT_TSC
2) X86_FEATURE_NONSTOP_TSC
3) X86_FEATURE_NONSTOP_TSC_S3
4) X86_FEATURE_TSC_ADJUST
5) At max. 4 sockets
After two decades of horrors we're finally at a point where TSC seems
to be halfway reliable and less abused by BIOS tinkerers. TSC_ADJUST
was really key as we can now detect even small modifications reliably
and the important point is that we can cure them as well (not pretty
but better than all other options)."
As feature #3 X86_FEATURE_NONSTOP_TSC_S3 only exists on several generations
of Atom processorz, and is always coupled with X86_FEATURE_CONSTANT_TSC
and X86_FEATURE_NONSTOP_TSC, skip checking it, and also be more defensive
to use maximal 2 sockets.
The check is done inside tsc_init() before registering 'tsc-early' and
'tsc' clocksources, as there were cases that both of them had been
wrongly judged as unreliable.
For more background of tsc/watchdog, there is a good summary in [2]
[tglx} Update vs. jiffies:
On systems where the only remaining clocksource aside of TSC is jiffies
there is no way to make this work because that creates a circular
dependency. Jiffies accuracy depends on not missing a periodic timer
interrupt, which is not guaranteed. That could be detected by TSC, but as
TSC is not trusted this cannot be compensated. The consequence is a
circulus vitiosus which results in shutting down TSC and falling back to
the jiffies clocksource which is even more unreliable.
[1]. https://lore.kernel.org/lkml/87eekfk8bd.fsf@nanos.tec.linutronix.de/
[2]. https://lore.kernel.org/lkml/87a6pimt1f.ffs@nanos.tec.linutronix.de/
[ tglx: Refine comment and amend changelog ]
Fixes: 6e3cd95234 ("x86/hpet: Use another crystalball to evaluate HPET usability")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20211117023751.24190-2-feng.tang@intel.com
Currently, WATCHDOG_THRESHOLD is set to detect a 62.5-millisecond skew in
a 500-millisecond WATCHDOG_INTERVAL. This requires that clocks be skewed
by more than 12.5% in order to be marked unstable. Except that a clock
that is skewed by that much is probably destroying unsuspecting software
right and left. And given that there are now checks for false-positive
skews due to delays between reading the two clocks, it should be possible
to greatly decrease WATCHDOG_THRESHOLD, at least for fine-grained clocks
such as TSC.
Therefore, add a new uncertainty_margin field to the clocksource structure
that contains the maximum uncertainty in nanoseconds for the corresponding
clock. This field may be initialized manually, as it is for
clocksource_tsc_early and clocksource_jiffies, which is copied to
refined_jiffies. If the field is not initialized manually, it will be
computed at clock-registry time as the period of the clock in question
based on the scale and freq parameters to __clocksource_update_freq_scale()
function. If either of those two parameters are zero, the
tens-of-milliseconds WATCHDOG_THRESHOLD is used as a cowardly alternative
to dividing by zero. No matter how the uncertainty_margin field is
calculated, it is bounded below by twice WATCHDOG_MAX_SKEW, that is, by 100
microseconds.
Note that manually initialized uncertainty_margin fields are not adjusted,
but there is a WARN_ON_ONCE() that triggers if any such field is less than
twice WATCHDOG_MAX_SKEW. This WARN_ON_ONCE() is intended to discourage
production use of the one-nanosecond uncertainty_margin values that are
used to test the clock-skew code itself.
The actual clock-skew check uses the sum of the uncertainty_margin fields
of the two clocksource structures being compared. Integer overflow is
avoided because the largest computed value of the uncertainty_margin
fields is one billion (10^9), and double that value fits into an
unsigned int. However, if someone manually specifies (say) UINT_MAX,
they will get what they deserve.
Note that the refined_jiffies uncertainty_margin field is initialized to
TICK_NSEC, which means that skew checks involving this clocksource will
be sufficently forgiving. In a similar vein, the clocksource_tsc_early
uncertainty_margin field is initialized to 32*NSEC_PER_MSEC, which
replicates the current behavior and allows custom setting if needed
in order to address the rare skews detected for this clocksource in
current mainline.
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210527190124.440372-4-paulmck@kernel.org
Some sorts of per-CPU clock sources have a history of going out of
synchronization with each other. However, this problem has purportedy been
solved in the past ten years. Except that it is all too possible that the
problem has instead simply been made less likely, which might mean that
some of the occasional "Marking clocksource 'tsc' as unstable" messages
might be due to desynchronization. How would anyone know?
Therefore apply CPU-to-CPU synchronization checking to newly unstable
clocksource that are marked with the new CLOCK_SOURCE_VERIFY_PERCPU flag.
Lists of desynchronized CPUs are printed, with the caveat that if it
is the reporting CPU that is itself desynchronized, it will appear that
all the other clocks are wrong. Just like in real life.
Reported-by: Chris Mason <clm@fb.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Feng Tang <feng.tang@intel.com>
Link: https://lore.kernel.org/r/20210527190124.440372-2-paulmck@kernel.org
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Merge tag 'x86_cleanups_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull misc x86 cleanups from Borislav Petkov:
"Trivial cleanups and fixes all over the place"
* tag 'x86_cleanups_for_v5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
MAINTAINERS: Remove me from IDE/ATAPI section
x86/pat: Do not compile stubbed functions when X86_PAT is off
x86/asm: Ensure asm/proto.h can be included stand-alone
x86/platform/intel/quark: Fix incorrect kernel-doc comment syntax in files
x86/msr: Make locally used functions static
x86/cacheinfo: Remove unneeded dead-store initialization
x86/process/64: Move cpu_current_top_of_stack out of TSS
tools/turbostat: Unmark non-kernel-doc comment
x86/syscalls: Fix -Wmissing-prototypes warnings from COND_SYSCALL()
x86/fpu/math-emu: Fix function cast warning
x86/msr: Fix wr/rdmsr_safe_regs_on_cpu() prototypes
x86: Fix various typos in comments, take #2
x86: Remove unusual Unicode characters from comments
x86/kaslr: Return boolean values from a function returning bool
x86: Fix various typos in comments
x86/setup: Remove unused RESERVE_BRK_ARRAY()
stacktrace: Move documentation for arch_stack_walk_reliable() to header
x86: Remove duplicate TSC DEADLINE MSR definitions
Fix ~144 single-word typos in arch/x86/ code comments.
Doing this in a single commit should reduce the churn.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: linux-kernel@vger.kernel.org
The time pvops functions are the only ones left which might be
used in 32-bit mode and which return a 64-bit value.
Switch them to use the static_call() mechanism instead of pvops, as
this allows quite some simplification of the pvops implementation.
Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20210311142319.4723-5-jgross@suse.com
Latch sequence counters have unique read and write APIs, and thus
seqcount_latch_t was recently introduced at seqlock.h.
Use that new data type instead of plain seqcount_t. This adds the
necessary type-safety and ensures that only latching-safe seqcount APIs
are to be used.
Signed-off-by: Ahmed S. Darwish <a.darwish@linutronix.de>
[peterz: unwreck cyc2ns_read_begin()]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200827114044.11173-7-a.darwish@linutronix.de
Changing base clock frequency directly impacts TSC Hz but not CPUID.16h
value. An overclocked CPU supporting CPUID.16h and with partial CPUID.15h
support will set TSC KHZ according to "best guess" given by CPUID.16h
relying on tsc_refine_calibration_work to give better numbers later.
tsc_refine_calibration_work will refuse to do its work when the outcome is
off the early TSC KHZ value by more than 1% which is certain to happen on
an overclocked system.
Fix this by adding a tsc_early_khz command line parameter that makes the
kernel skip early TSC calibration and use the given value instead.
This allows the user to provide the expected TSC frequency that is closer
to reality than the one reported by the hardware, enabling
tsc_refine_calibration_work to do meaningful error checking.
[ tglx: Made the variable __initdata as it's only used on init and
removed the error checking in the argument parser because
kstrto*() only stores to the variable if the string is valid ]
Signed-off-by: Krzysztof Piecuch <piecuch@protonmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/O2CpIOrqLZHgNRkfjRpz_LGqnc1ix_seNIiOCvHY4RHoulOVRo6kMXKuLOfBVTi0SMMevg6Go1uZ_cL9fLYtYdTRNH78ChaFaZyG3VAyYz8=@protonmail.com
Pull x86 cleanups from Ingo Molnar:
"This topic tree contains more commits than usual:
- most of it are uaccess cleanups/reorganization by Al
- there's a bunch of prototype declaration (--Wmissing-prototypes)
cleanups
- misc other cleanups all around the map"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits)
x86/mm/set_memory: Fix -Wmissing-prototypes warnings
x86/efi: Add a prototype for efi_arch_mem_reserve()
x86/mm: Mark setup_emu2phys_nid() static
x86/jump_label: Move 'inline' keyword placement
x86/platform/uv: Add a missing prototype for uv_bau_message_interrupt()
kill uaccess_try()
x86: unsafe_put-style macro for sigmask
x86: x32_setup_rt_frame(): consolidate uaccess areas
x86: __setup_rt_frame(): consolidate uaccess areas
x86: __setup_frame(): consolidate uaccess areas
x86: setup_sigcontext(): list user_access_{begin,end}() into callers
x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit)
x86: ia32_setup_rt_frame(): consolidate uaccess areas
x86: ia32_setup_frame(): consolidate uaccess areas
x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers
x86/alternatives: Mark text_poke_loc_init() static
x86/cpu: Fix a -Wmissing-prototypes warning for init_ia32_feat_ctl()
x86/mm: Drop pud_mknotpresent()
x86: Replace setup_irq() by request_irq()
x86/configs: Slightly reduce defconfigs
...
All architectures which use the generic VDSO code have their own storage
for the VDSO clock mode. That's pointless and just requires duplicate code.
X86 abuses the function which retrieves the architecture specific clock
mode storage to mark the clocksource as used in the VDSO. That's silly
because this is invoked on every tick when the VDSO data is updated.
Move this functionality to the clocksource::enable() callback so it gets
invoked once when the clocksource is installed. This allows to make the
clock mode storage generic.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Michael Kelley <mikelley@microsoft.com> (Hyper-V parts)
Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> (VDSO parts)
Acked-by: Juergen Gross <jgross@suse.com> (Xen parts)
Link: https://lkml.kernel.org/r/20200207124402.934519777@linutronix.de
Fix a couple of typos in code comments.
[ bp: While at it: s/IRQ's/IRQs/. ]
Signed-off-by: Martin Molnar <martin.molnar.programming@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://lkml.kernel.org/r/0819a044-c360-44a4-f0b6-3f5bafe2d35c@gmail.com
The introduction of clocksource_tsc_early broke the functionality of
"tsc=reliable" and "tsc=nowatchdog" command line parameters, since
clocksource_tsc_early is unconditionally registered with
CLOCK_SOURCE_MUST_VERIFY and thus put on the watchdog list.
This can cause the TSC to be declared unstable during boot:
clocksource: timekeeping watchdog on CPU0: Marking clocksource
'tsc-early' as unstable because the skew is too large:
clocksource: 'refined-jiffies' wd_now: fffb7018 wd_last: fffb6e9d
mask: ffffffff
clocksource: 'tsc-early' cs_now: 68a6a7070f6a0 cs_last: 68a69ab6f74d6
mask: ffffffffffffffff
tsc: Marking TSC unstable due to clocksource watchdog
The corresponding elapsed times are cs_nsec=1224152026 and wd_nsec=378942392, so
the watchdog differs from TSC by 0.84 seconds.
This happens when HPET is not available and jiffies are used as the TSC
watchdog instead and the jiffies update is not happening due to lost timer
interrupts in periodic mode, which can happen e.g. with expensive debug
mechanisms enabled or under massive overload conditions in virtualized
environments.
Before the introduction of the early TSC clocksource the command line
parameters "tsc=reliable" and "tsc=nowatchdog" could be used to work around
this issue.
Restore the behaviour by disabling the watchdog if requested on the kernel
command line.
[ tglx: Clarify changelog ]
Fixes: aa83c45762 ("x86/tsc: Introduce early tsc clocksource")
Signed-off-by: Michael Zhivich <mzhivich@akamai.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20191024175945.14338-1-mzhivich@akamai.com
Currently big microservers have _XEON_D while small microservers have
_X, Make it uniformly: _D.
for i in `git grep -l "\(INTEL_FAM6_\|VULNWL_INTEL\|INTEL_CPU_FAM6\).*_\(X\|XEON_D\)"`
do
sed -i -e 's/\(\(INTEL_FAM6_\|VULNWL_INTEL\|INTEL_CPU_FAM6\).*ATOM.*\)_X/\1_D/g' \
-e 's/\(\(INTEL_FAM6_\|VULNWL_INTEL\|INTEL_CPU_FAM6\).*\)_XEON_D/\1_D/g' ${i}
done
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Cc: x86@kernel.org
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Link: https://lkml.kernel.org/r/20190827195122.677152989@infradead.org
Pull x86 cleanups from Ingo Molnar:
"Misc small cleanups: removal of superfluous code and coding style
cleanups mostly"
* 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/kexec: Make variable static and config dependent
x86/defconfigs: Remove useless UEVENT_HELPER_PATH
x86/amd_nb: Make hygon_nb_misc_ids static
x86/tsc: Move inline keyword to the beginning of function declarations
x86/io_delay: Define IO_DELAY macros in C instead of Kconfig
x86/io_delay: Break instead of fallthrough in switch statement
Pull x96 apic updates from Thomas Gleixner:
"Updates for the x86 APIC interrupt handling and APIC timer:
- Fix a long standing issue with spurious interrupts which was caused
by the big vector management rework a few years ago. Robert Hodaszi
provided finally enough debug data and an excellent initial failure
analysis which allowed to understand the underlying issues.
This contains a change to the core interrupt management code which
is required to handle this correctly for the APIC/IO_APIC. The core
changes are NOOPs for most architectures except ARM64. ARM64 is not
impacted by the change as confirmed by Marc Zyngier.
- Newer systems allow to disable the PIT clock for power saving
causing panic in the timer interrupt delivery check of the IO/APIC
when the HPET timer is not enabled either. While the clock could be
turned on this would cause an endless whack a mole game to chase
the proper register in each affected chipset.
These systems provide the relevant frequencies for TSC, CPU and the
local APIC timer via CPUID and/or MSRs, which allows to avoid the
PIT/HPET based calibration. As the calibration code is the only
usage of the legacy timers on modern systems and is skipped anyway
when the frequencies are known already, there is no point in
setting up the PIT and actually checking for the interrupt delivery
via IO/APIC.
To achieve this on a wide variety of platforms, the CPUID/MSR based
frequency readout has been made more robust, which also allowed to
remove quite some workarounds which turned out to be not longer
required. Thanks to Daniel Drake for analysis, patches and
verification"
* 'x86-apic-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/irq: Seperate unused system vectors from spurious entry again
x86/irq: Handle spurious interrupt after shutdown gracefully
x86/ioapic: Implement irq_get_irqchip_state() callback
genirq: Add optional hardware synchronization for shutdown
genirq: Fix misleading synchronize_irq() documentation
genirq: Delay deactivation in free_irq()
x86/timer: Skip PIT initialization on modern chipsets
x86/apic: Use non-atomic operations when possible
x86/apic: Make apic_bsp_setup() static
x86/tsc: Set LAPIC timer period to crystal clock frequency
x86/apic: Rename 'lapic_timer_frequency' to 'lapic_timer_period'
x86/tsc: Use CPUID.0x16 to calculate missing crystal frequency
