From: Sean Christopherson <seanjc@google.com>
To: Michael Kelley <mhklinux@outlook.com>
Cc: Jonathan Corbet <corbet@lwn.net>,
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Subject: Re: [PATCH v5 01/51] x86/apic: Provide helpers to set local APIC timer period in hz and khz
Date: Mon, 6 Jul 2026 11:00:23 -0700 [thread overview]
Message-ID: <akvtN7aIjZ7gOq4o@google.com> (raw)
In-Reply-To: <SN6PR02MB41578D3C34AB283B892C27A4D4F52@SN6PR02MB4157.namprd02.prod.outlook.com>
On Thu, Jul 02, 2026, Michael Kelley wrote:
> > @@ -796,6 +796,16 @@ bool __init apic_needs_pit(void)
> > return lapic_timer_period == 0;
> > }
> >
> > +void apic_set_timer_period_khz(u64 period_khz, const char *source)
> > +{
> > + lapic_timer_period = mul_u64_u32_div(period_khz, 1000, HZ);
> > +}
> > +
> > +void apic_set_timer_period_hz(u64 period_hz, const char *source)
> > +{
> > + lapic_timer_period = div_u64(period_hz, HZ);
> > +}
>
> A string "source" argument is passed in, but not used. Is there an
> envisioned future use? Also, this function doesn't output a pr_info()
> message like the existing Hyper-V and VMware code does.
It was a complete goof on my part (Sashiko also pointed out the oddity[*]). I
fully intended to log a message and provide equivalent Hyper-V/VMware behavior,
and totally spaced it.
[*] https://lore.kernel.org/all/20260701194621.4BD691F000E9@smtp.kernel.org
> I don't know that the message is all that useful, though I do remember one
> case where I was debugging some clock/timer issue when I looked at it.
next prev parent reply other threads:[~2026-07-06 18:00 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-01 19:31 [PATCH v5 00/51] x86: Try to wrangle PV clocks vs. TSC Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 01/51] x86/apic: Provide helpers to set local APIC timer period in hz and khz Sean Christopherson
2026-07-02 17:47 ` Michael Kelley
2026-07-06 18:00 ` Sean Christopherson [this message]
2026-07-01 19:31 ` [PATCH v5 02/51] x86/apic: Add CONFIG_X86_LOCAL_APIC=n stubs for apic_set_timer_period_{,k}hz() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 03/51] x86/tsc: Ensure that TSC recalibration doesn't run if TSC frequency is known Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 04/51] x86/tsc: Restrict recalibrate_cpu_khz() export to p4-clockmod and powernow-k7 Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 05/51] x86/sev: Mark TSC as reliable when configuring Secure TSC Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 06/51] x86/sev: Don't override CPU frequency calibration for SNP's " Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 07/51] x86/sev: Move check for SNP Secure TSC support to tsc_early_init() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 08/51] x86/sev: Shove SNP's secure/trusted TSC frequency directly into "calibration" Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 09/51] x86/tsc: Add a standalone helper for getting TSC info from CPUID.0x15 Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 10/51] x86/tdx: Force TSC frequency with CPUID-based info provided by the TDX-Module Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 11/51] x86/tsc: Add dedicated hypervisor hooks for getting known TSC/CPU frequencies Sean Christopherson
2026-07-02 17:47 ` Michael Kelley
2026-07-01 19:31 ` [PATCH v5 12/51] x86/acrn: Register TSC/CPU frequency callbacks iff frequency is actually in CPUID Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 13/51] x86/acrn: Mark TSC frequency as known when using ACRN for calibration Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 14/51] x86/tsc: Consolidate forcing of X86_FEATURE_TSC_KNOWN_FREQ for PV code Sean Christopherson
2026-07-02 17:47 ` Michael Kelley
2026-07-01 19:31 ` [PATCH v5 15/51] x86/tsc: Kill off x86_platform_ops.calibrate_{cpu,tsc}() hooks Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 16/51] x86/tsc: Rename pit_hpet_ptimer_calibrate_cpu() => native_calibrate_cpu_late() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 17/51] x86/tsc: Fold native_calibrate_cpu() into recalibrate_cpu_khz() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 18/51] x86/kvmclock: Rename kvm_get_tsc_khz() to kvmclock_get_tsc_khz() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 19/51] x86/kvmclock: Drop dead check on TSC being unstable during kvmclock_init() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 20/51] KVM: x86: Officially define CPUID 0x40000010 as PV Timing Info (TSC and Bus) Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 21/51] x86/kvm: Obtain TSC frequency from PV CPUID if present Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 22/51] x86/kvm: Mark TSC as reliable when it's constant and nonstop Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 23/51] x86/tsc: Add standalone helper for getting CPU frequency from CPUID Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 24/51] x86/kvm: Get CPU base frequency from CPUID when it's available Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 25/51] clocksource: hyper-v: Register sched_clock save/restore iff it's necessary Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 26/51] clocksource: hyper-v: Drop wrappers to sched_clock save/restore helpers Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 27/51] clocksource: hyper-v: Don't save/restore TSC offset when using HV sched_clock Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 28/51] x86/kvmclock: Setup kvmclock for secondary CPUs iff CONFIG_SMP=y Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 29/51] x86/kvm: Don't disable kvmclock on BSP in syscore_suspend() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 30/51] x86/paravirt: Remove unnecessary PARAVIRT=n stub for paravirt_set_sched_clock() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 31/51] x86/paravirt: Move handling of unstable PV clocks into paravirt_set_sched_clock() Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 32/51] x86/kvmclock: Move sched_clock save/restore helpers up in kvmclock.c Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 33/51] x86/xen/time: NOP-ify x86_platform's sched_clock save/restore hooks Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 34/51] x86/vmware: NOP-ify save/restore hooks when using VMware's sched_clock Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 35/51] x86/tsc: WARN if TSC sched_clock save/restore used with PV sched_clock Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 36/51] x86/paravirt: Pass sched_clock save/restore helpers during registration Sean Christopherson
2026-07-02 17:48 ` Michael Kelley
2026-07-01 19:31 ` [PATCH v5 37/51] x86/kvmclock: Move kvm_sched_clock_init() down in kvmclock.c Sean Christopherson
2026-07-01 19:31 ` [PATCH v5 38/51] x86/xen/time: Mark xen_setup_vsyscall_time_info() as __init Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 39/51] x86/pvclock: Mark setup helpers and related various as __init/__ro_after_init Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 40/51] x86/pvclock: WARN if pvclock's valid_flags are overwritten Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 41/51] x86/kvmclock: Refactor handling of PVCLOCK_TSC_STABLE_BIT during kvmclock_init() Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 42/51] timekeeping: Resume clocksources before reading persistent clock Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 43/51] x86/kvmclock: Hook clocksource.suspend/resume when kvmclock isn't sched_clock Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 44/51] x86/kvmclock: WARN if wall clock is read while kvmclock is suspended Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 45/51] x86/paravirt: Mark __paravirt_set_sched_clock() as __init Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 46/51] x86/paravirt: Plumb a return code into __paravirt_set_sched_clock() Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 47/51] x86/paravirt: Don't use a PV sched_clock in CoCo guests with trusted TSC Sean Christopherson
2026-07-02 17:48 ` Michael Kelley
2026-07-01 19:32 ` [PATCH v5 48/51] x86/kvmclock: Use TSC for sched_clock if it's constant and non-stop Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 49/51] x86/kvmclock: Plumb in AP-online and BSP-resume to kvmlock, for documentation Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 50/51] x86/paravirt: Move using_native_sched_clock() stub into timer.h Sean Christopherson
2026-07-01 19:32 ` [PATCH v5 51/51] x86/kvm: Get local APIC bus frequency from PV CPUID Timing Info Sean Christopherson
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