kernel.git/arch/x86/kernel/smpboot.c, branch linux-5.7.y

x86, sched: Bail out of frequency invariance if turbo_freq/base_freq gives 0

2020-08-19T06:23:25Z

[ Upstream commit f4291df103315a696f0b8c4f45ca8ae773c17441 ] Be defensive against the case where the processor reports a base_freq larger than turbo_freq (the ratio would be zero). Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20200531182453.15254-4-ggherdovich@suse.cz Signed-off-by: Sasha Levin

x86, sched: Bail out of frequency invariance if turbo frequency is unknown

2020-08-19T06:23:25Z

[ Upstream commit 51beea8862a3095559862df39554f05042e1195b ] There may be CPUs that support turbo boost but don't declare any turbo ratio, i.e. their MSR_TURBO_RATIO_LIMIT is all zeroes. In that condition scale-invariant calculations can't be performed. Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Suggested-by: Ricardo Neri Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Rafael J. Wysocki Tested-by: Ricardo Neri Link: https://lkml.kernel.org/r/20200531182453.15254-3-ggherdovich@suse.cz Signed-off-by: Sasha Levin

x86: Fix early boot crash on gcc-10, third try

2020-05-15T09:48:01Z

... or the odyssey of trying to disable the stack protector for the function which generates the stack canary value. The whole story started with Sergei reporting a boot crash with a kernel built with gcc-10: Kernel panic — not syncing: stack-protector: Kernel stack is corrupted in: start_secondary CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.6.0-rc5—00235—gfffb08b37df9 #139 Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./H77M—D3H, BIOS F12 11/14/2013 Call Trace: dump_stack panic ? start_secondary __stack_chk_fail start_secondary secondary_startup_64 -—-[ end Kernel panic — not syncing: stack—protector: Kernel stack is corrupted in: start_secondary This happens because gcc-10 tail-call optimizes the last function call in start_secondary() - cpu_startup_entry() - and thus emits a stack canary check which fails because the canary value changes after the boot_init_stack_canary() call. To fix that, the initial attempt was to mark the one function which generates the stack canary with: __attribute__((optimize("-fno-stack-protector"))) ... start_secondary(void *unused) however, using the optimize attribute doesn't work cumulatively as the attribute does not add to but rather replaces previously supplied optimization options - roughly all -fxxx options. The key one among them being -fno-omit-frame-pointer and thus leading to not present frame pointer - frame pointer which the kernel needs. The next attempt to prevent compilers from tail-call optimizing the last function call cpu_startup_entry(), shy of carving out start_secondary() into a separate compilation unit and building it with -fno-stack-protector, was to add an empty asm(""). This current solution was short and sweet, and reportedly, is supported by both compilers but we didn't get very far this time: future (LTO?) optimization passes could potentially eliminate this, which leads us to the third attempt: having an actual memory barrier there which the compiler cannot ignore or move around etc. That should hold for a long time, but hey we said that about the other two solutions too so... Reported-by: Sergei Trofimovich Signed-off-by: Borislav Petkov Tested-by: Kalle Valo Cc: Link: https://lkml.kernel.org/r/20200314164451.346497-1-slyfox@gentoo.org

x86, sched: Move check for CPU type to caller function

2020-04-22T21:10:13Z

Improve readability of the function intel_set_max_freq_ratio() by moving the check for KNL CPUs there, together with checks for GLM and SKX. Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20200416054745.740-5-ggherdovich@suse.cz

x86, sched: Don't enable static key when starting secondary CPUs

2020-04-22T21:10:13Z

The static key arch_scale_freq_key only needs to be enabled once (at boot). This change fixes a bug by which the key was enabled every time cpu0 is started, even as a secondary CPU during cpu hotplug. Secondary CPUs are started from the idle thread: setting a static key from there means acquiring a lock and may result in sleeping in the idle task, causing CPU lockup. Another consequence of this change is that init_counter_refs() is now called on each CPU correctly; previously the function on_each_cpu() was used, but it was called at boot when the only online cpu is cpu0. [ggherdovich@suse.cz: Tested and wrote changelog] Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Reported-by: Chris Wilson Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20200416054745.740-4-ggherdovich@suse.cz

x86, sched: Account for CPUs with less than 4 cores in freq. invariance

2020-04-22T21:10:13Z

If a CPU has less than 4 physical cores, MSR_TURBO_RATIO_LIMIT will rightfully report that the 4C turbo ratio is zero. In such cases, use the 1C turbo ratio instead for frequency invariance calculations. Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Reported-by: Like Xu Reported-by: Neil Rickert Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Tested-by: Dave Kleikamp Link: https://lkml.kernel.org/r/20200416054745.740-3-ggherdovich@suse.cz

x86, sched: Bail out of frequency invariance if base frequency is unknown

2020-04-22T21:10:13Z

Some hypervisors such as VMWare ESXi 5.5 advertise support for X86_FEATURE_APERFMPERF but then fill all MSR's with zeroes. In particular, MSR_PLATFORM_INFO set to zero tricks the code that wants to know the base clock frequency of the CPU (highest non-turbo frequency), producing a division by zero when computing the ratio turbo_freq/base_freq necessary for frequency invariant accounting. It is to be noted that even if MSR_PLATFORM_INFO contained the appropriate data, APERF and MPERF are constantly zero on ESXi 5.5, thus freq-invariance couldn't be done in principle (not that it would make a lot of sense in a VM anyway). The real problem is advertising X86_FEATURE_APERFMPERF. This appears to be fixed in more recent versions: ESXi 6.7 doesn't advertise that feature. Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance") Signed-off-by: Giovanni Gherdovich Signed-off-by: Peter Zijlstra (Intel) Acked-by: Rafael J. Wysocki Link: https://lkml.kernel.org/r/20200416054745.740-2-ggherdovich@suse.cz

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 ...

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

2020-03-31T00:01:51Z

Pull scheduler updates from Ingo Molnar: "The main changes in this cycle are: - Various NUMA scheduling updates: harmonize the load-balancer and NUMA placement logic to not work against each other. The intended result is better locality, better utilization and fewer migrations. - Introduce Thermal Pressure tracking and optimizations, to improve task placement on thermally overloaded systems. - Implement frequency invariant scheduler accounting on (some) x86 CPUs. This is done by observing and sampling the 'recent' CPU frequency average at ~tick boundaries. The CPU provides this data via the APERF/MPERF MSRs. This hopefully makes our capacity estimates more precise and keeps tasks on the same CPU better even if it might seem overloaded at a lower momentary frequency. (As usual, turbo mode is a complication that we resolve by observing the maximum frequency and renormalizing to it.) - Add asymmetric CPU capacity wakeup scan to improve capacity utilization on asymmetric topologies. (big.LITTLE systems) - PSI fixes and optimizations. - RT scheduling capacity awareness fixes & improvements. - Optimize the CONFIG_RT_GROUP_SCHED constraints code. - Misc fixes, cleanups and optimizations - see the changelog for details" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (62 commits) threads: Update PID limit comment according to futex UAPI change sched/fair: Fix condition of avg_load calculation sched/rt: cpupri_find: Trigger a full search as fallback kthread: Do not preempt current task if it is going to call schedule() sched/fair: Improve spreading of utilization sched: Avoid scale real weight down to zero psi: Move PF_MEMSTALL out of task->flags MAINTAINERS: Add maintenance information for psi psi: Optimize switching tasks inside shared cgroups psi: Fix cpu.pressure for cpu.max and competing cgroups sched/core: Distribute tasks within affinity masks sched/fair: Fix enqueue_task_fair warning thermal/cpu-cooling, sched/core: Move the arch_set_thermal_pressure() API to generic scheduler code sched/rt: Remove unnecessary push for unfit tasks sched/rt: Allow pulling unfitting task sched/rt: Optimize cpupri_find() on non-heterogenous systems sched/rt: Re-instate old behavior in select_task_rq_rt() sched/rt: cpupri_find: Implement fallback mechanism for !fit case sched/fair: Fix reordering of enqueue/dequeue_task_fair() sched/fair: Fix runnable_avg for throttled cfs ...

x86/kernel: Convert to new CPU match macros

2020-03-24T20:28:26Z

The new macro set has a consistent namespace and uses C99 initializers instead of the grufty C89 ones. Get rid the of the local macro wrappers for consistency. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Reviewed-by: Greg Kroah-Hartman Link: https://lkml.kernel.org/r/20200320131509.250559388@linutronix.de