kernel.git/arch/x86/kernel/tsc.c, branch linux-5.12.y

clocksource: Check per-CPU clock synchronization when marked unstable

2021-07-14T14:59:28Z

[ Upstream commit 7560c02bdffb7c52d1457fa551b9e745d4b9e754 ] 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 Signed-off-by: Paul E. McKenney Signed-off-by: Thomas Gleixner Acked-by: Feng Tang Link: https://lore.kernel.org/r/20210527190124.440372-2-paulmck@kernel.org Signed-off-by: Sasha Levin

x86/tsc: Use seqcount_latch_t

2020-09-10T09:19:29Z

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 [peterz: unwreck cyc2ns_read_begin()] Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20200827114044.11173-7-a.darwish@linutronix.de

x86/tsc: Add tsc_early_khz command line parameter

2020-05-21T21:07:00Z

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 Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/O2CpIOrqLZHgNRkfjRpz_LGqnc1ix_seNIiOCvHY4RHoulOVRo6kMXKuLOfBVTi0SMMevg6Go1uZ_cL9fLYtYdTRNH78ChaFaZyG3VAyYz8=@protonmail.com

Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T18:04:05Z

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 ...

x86/vdso: Use generic VDSO clock mode storage

2020-02-17T13:40:23Z

Switch to the generic VDSO clock mode storage. Signed-off-by: Thomas Gleixner Reviewed-by: Vincenzo Frascino (VDSO parts) Acked-by: Juergen Gross (Xen parts) Acked-by: Paolo Bonzini (KVM parts) Link: https://lkml.kernel.org/r/20200207124403.152039903@linutronix.de

x86/vdso: Move VDSO clocksource state tracking to callback

2020-02-17T13:40:22Z

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 Reviewed-by: Michael Kelley (Hyper-V parts) Reviewed-by: Vincenzo Frascino (VDSO parts) Acked-by: Juergen Gross (Xen parts) Link: https://lkml.kernel.org/r/20200207124402.934519777@linutronix.de

x86: Fix a handful of typos

2020-02-16T19:58:06Z

Fix a couple of typos in code comments. [ bp: While at it: s/IRQ's/IRQs/. ] Signed-off-by: Martin Molnar Signed-off-by: Borislav Petkov Reviewed-by: Randy Dunlap Link: https://lkml.kernel.org/r/0819a044-c360-44a4-f0b6-3f5bafe2d35c@gmail.com

x86/tsc: Respect tsc command line paraemeter for clocksource_tsc_early

2019-11-05T00:24:56Z

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: aa83c45762a24 ("x86/tsc: Introduce early tsc clocksource") Signed-off-by: Michael Zhivich Signed-off-by: Thomas Gleixner Link: https://lkml.kernel.org/r/20191024175945.14338-1-mzhivich@akamai.com

x86/intel: Aggregate microserver naming

2019-08-28T09:29:32Z

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) Reviewed-by: Tony Luck Cc: x86@kernel.org Cc: Dave Hansen Cc: Thomas Gleixner Cc: Borislav Petkov Link: https://lkml.kernel.org/r/20190827195122.677152989@infradead.org

Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2019-07-09T00:27:24Z

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