Re: [PATCH] x86, apic: Add apic calibration hook.

From: Alok Kataria
Date: Wed Sep 01 2010 - 15:30:18 EST

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On Fri, 2010-08-27 at 14:28 -0700, Alok Kataria wrote:
> Hi Thomas,
>
> On Tue, 2010-08-24 at 14:58 -0700, Alok Kataria wrote:
> > On Tue, 2010-08-24 at 14:51 -0700, Thomas Gleixner wrote:
> > > On Tue, 24 Aug 2010, Alok Kataria wrote:
> > > > > > +
> > > > > > + if (lapic_clockevent.mult)
> > > > > > + return 0;
> > > > >
> > > > > Why is this necessary ? calibrate_APIC_clock() is only called once.
> > > > >
> > > >
> > > > Yes, though timer.calibrate_apci() could behave differently on different
> > > > platforms. For eg. the vmware_calibrate_apic doesn't initialize any of
> > > > the lapic_clockevent state and we need this to set it up in that case.
> > >
> > > Can we please make this consistent ?
>
> How does this patch look ?

Thomas, any comments on the patch below, just want to make sure that
this didn't fell through the cracks.

Thanks,
Alok

> --
>
> Add apic calibration hook.
>
> From: Alok N Kataria <akataria@xxxxxxxxxx>
>
> Add a new function ptr calibrate_apic to x86_init_ops structure. On native this
> does the usual apic calibration. On VMware's platform we override it with a
> routine which gets that information from the hypervisor.
>
> Signed-off-by: Alok N Kataria <akataria@xxxxxxxxxx>
> Cc: H. Peter Anvin <hpa@xxxxxxxxx>
> ---
>
> arch/x86/include/asm/apic.h | 6 +++
> arch/x86/include/asm/x86_init.h | 2 +
> arch/x86/kernel/apic/apic.c | 88 ++++++++++++++++++++-------------------
> arch/x86/kernel/cpu/vmware.c | 30 ++++++++++++-
> arch/x86/kernel/x86_init.c | 1
> 5 files changed, 82 insertions(+), 45 deletions(-)
>
>
> diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
> index 1fa03e0..5012ee5 100644
> --- a/arch/x86/include/asm/apic.h
> +++ b/arch/x86/include/asm/apic.h
> @@ -17,6 +17,10 @@
>
> #define ARCH_APICTIMER_STOPS_ON_C3 1
>
> +/* Clock divisor */
> +#define APIC_DIVISOR 16
> +#define LAPIC_CAL_LOOPS (HZ/10)
> +
> /*
> * Debugging macros
> */
> @@ -238,6 +242,8 @@ extern void setup_boot_APIC_clock(void);
> extern void setup_secondary_APIC_clock(void);
> extern int APIC_init_uniprocessor(void);
> extern void enable_NMI_through_LVT0(void);
> +extern int native_calibrate_apic(void);
> +extern int initialize_lapic(long delta, unsigned int calibration_result);
>
> /*
> * On 32bit this is mach-xxx local
> diff --git a/arch/x86/include/asm/x86_init.h b/arch/x86/include/asm/x86_init.h
> index baa579c..58f982b 100644
> --- a/arch/x86/include/asm/x86_init.h
> +++ b/arch/x86/include/asm/x86_init.h
> @@ -83,11 +83,13 @@ struct x86_init_paging {
> * boot cpu
> * @tsc_pre_init: platform function called before TSC init
> * @timer_init: initialize the platform timer (default PIT/HPET)
> + * @calibrate_apic: calibrate APIC bus freq (ticks per HZ)
> */
> struct x86_init_timers {
> void (*setup_percpu_clockev)(void);
> void (*tsc_pre_init)(void);
> void (*timer_init)(void);
> + int (*calibrate_apic)(void);
> };
>
> /**
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index e3b534c..ca5d084 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -176,7 +176,7 @@ static struct resource lapic_resource = {
> .flags = IORESOURCE_MEM | IORESOURCE_BUSY,
> };
>
> -static unsigned int calibration_result;
> +static unsigned int apic_calibration_res;
>
> static int lapic_next_event(unsigned long delta,
> struct clock_event_device *evt);
> @@ -326,13 +326,6 @@ int lapic_get_maxlvt(void)
> }
>
> /*
> - * Local APIC timer
> - */
> -
> -/* Clock divisor */
> -#define APIC_DIVISOR 16
> -
> -/*
> * This function sets up the local APIC timer, with a timeout of
> * 'clocks' APIC bus clock. During calibration we actually call
> * this function twice on the boot CPU, once with a bogus timeout
> @@ -431,7 +424,7 @@ static void lapic_timer_setup(enum clock_event_mode mode,
> switch (mode) {
> case CLOCK_EVT_MODE_PERIODIC:
> case CLOCK_EVT_MODE_ONESHOT:
> - __setup_APIC_LVTT(calibration_result,
> + __setup_APIC_LVTT(apic_calibration_res,
> mode != CLOCK_EVT_MODE_PERIODIC, 1);
> break;
> case CLOCK_EVT_MODE_UNUSED:
> @@ -500,8 +493,6 @@ static void __cpuinit setup_APIC_timer(void)
> * back to normal later in the boot process).
> */
>
> -#define LAPIC_CAL_LOOPS (HZ/10)
> -
> static __initdata int lapic_cal_loops = -1;
> static __initdata long lapic_cal_t1, lapic_cal_t2;
> static __initdata unsigned long long lapic_cal_tsc1, lapic_cal_tsc2;
> @@ -590,13 +581,50 @@ calibrate_by_pmtimer(long deltapm, long *delta, long *deltatsc)
> return 0;
> }
>
> -static int __init calibrate_APIC_clock(void)
> +int __init initialize_lapic(long delta, unsigned int calibration_result)
> +{
> + struct clock_event_device *levt = &__get_cpu_var(lapic_events);
> +
> + /* Calculate the scaled math multiplication factor */
> + lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
> + lapic_clockevent.shift);
> + lapic_clockevent.max_delta_ns =
> + clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
> + lapic_clockevent.min_delta_ns =
> + clockevent_delta2ns(0xF, &lapic_clockevent);
> +
> + apic_calibration_res = calibration_result;
> +
> + apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
> + apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
> + apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
> + calibration_result);
> +
> + apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
> + "%u.%04u MHz.\n",
> + calibration_result / (1000000 / HZ),
> + calibration_result % (1000000 / HZ));
> +
> + /*
> + * Do a sanity check on the APIC calibration result
> + */
> + if (calibration_result < (1000000 / HZ)) {
> + pr_warning("APIC frequency too slow, disabling apic timer\n");
> + return -1;
> + }
> +
> + levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> + return 0;
> +}
> +
> +int __init native_calibrate_apic(void)
> {
> struct clock_event_device *levt = &__get_cpu_var(lapic_events);
> void (*real_handler)(struct clock_event_device *dev);
> unsigned long deltaj;
> long delta, deltatsc;
> int pm_referenced = 0;
> + unsigned int calibration_result;
>
> local_irq_disable();
>
> @@ -631,20 +659,12 @@ static int __init calibrate_APIC_clock(void)
> pm_referenced = !calibrate_by_pmtimer(lapic_cal_pm2 - lapic_cal_pm1,
> &delta, &deltatsc);
>
> - /* Calculate the scaled math multiplication factor */
> - lapic_clockevent.mult = div_sc(delta, TICK_NSEC * LAPIC_CAL_LOOPS,
> - lapic_clockevent.shift);
> - lapic_clockevent.max_delta_ns =
> - clockevent_delta2ns(0x7FFFFF, &lapic_clockevent);
> - lapic_clockevent.min_delta_ns =
> - clockevent_delta2ns(0xF, &lapic_clockevent);
> -
> calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
>
> - apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
> - apic_printk(APIC_VERBOSE, "..... mult: %u\n", lapic_clockevent.mult);
> - apic_printk(APIC_VERBOSE, "..... calibration result: %u\n",
> - calibration_result);
> + if (initialize_lapic(delta, calibration_result)) {
> + local_irq_enable();
> + return -1;
> + }
>
> if (cpu_has_tsc) {
> apic_printk(APIC_VERBOSE, "..... CPU clock speed is "
> @@ -653,22 +673,6 @@ static int __init calibrate_APIC_clock(void)
> (deltatsc / LAPIC_CAL_LOOPS) % (1000000 / HZ));
> }
>
> - apic_printk(APIC_VERBOSE, "..... host bus clock speed is "
> - "%u.%04u MHz.\n",
> - calibration_result / (1000000 / HZ),
> - calibration_result % (1000000 / HZ));
> -
> - /*
> - * Do a sanity check on the APIC calibration result
> - */
> - if (calibration_result < (1000000 / HZ)) {
> - local_irq_enable();
> - pr_warning("APIC frequency too slow, disabling apic timer\n");
> - return -1;
> - }
> -
> - levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> -
> /*
> * PM timer calibration failed or not turned on
> * so lets try APIC timer based calibration
> @@ -706,7 +710,7 @@ static int __init calibrate_APIC_clock(void)
>
> if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
> pr_warning("APIC timer disabled due to verification failure\n");
> - return -1;
> + return -1;
> }
>
> return 0;
> @@ -738,7 +742,7 @@ void __init setup_boot_APIC_clock(void)
> apic_printk(APIC_VERBOSE, "Using local APIC timer interrupts.\n"
> "calibrating APIC timer ...\n");
>
> - if (calibrate_APIC_clock()) {
> + if (x86_init.timers.calibrate_apic()) {
> /* No broadcast on UP ! */
> if (num_possible_cpus() > 1)
> setup_APIC_timer();
> diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
> index 227b044..e8b760e 100644
> --- a/arch/x86/kernel/cpu/vmware.c
> +++ b/arch/x86/kernel/cpu/vmware.c
> @@ -26,6 +26,7 @@
> #include <asm/div64.h>
> #include <asm/x86_init.h>
> #include <asm/hypervisor.h>
> +#include <asm/apic.h>
>
> #define CPUID_VMWARE_INFO_LEAF 0x40000000
> #define VMWARE_HYPERVISOR_MAGIC 0x564D5868
> @@ -72,17 +73,40 @@ static unsigned long vmware_get_tsc_khz(void)
> return tsc_hz;
> }
>
> +static int __init vmware_calibrate_apic(void)
> +{
> + unsigned int calibration_result;
> + uint32_t eax, ebx, ecx, edx;
> + int err;
> + long delta;
> + unsigned long flags;
> +
> + VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
> + BUG_ON(!ecx);
> + calibration_result = ecx / HZ;
> +
> + printk(KERN_INFO "APIC bus freq read from hypervisor\n");
> +
> + delta = (calibration_result * LAPIC_CAL_LOOPS) / APIC_DIVISOR;
> + local_irq_save(flags);
> + err = initialize_lapic(delta, calibration_result);
> + local_irq_restore(flags);
> +
> + return err;
> +}
> +
> static void __init vmware_platform_setup(void)
> {
> uint32_t eax, ebx, ecx, edx;
>
> VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
>
> - if (ebx != UINT_MAX)
> + if (ebx != UINT_MAX) {
> x86_platform.calibrate_tsc = vmware_get_tsc_khz;
> - else
> + x86_init.timers.calibrate_apic = vmware_calibrate_apic;
> + } else
> printk(KERN_WARNING
> - "Failed to get TSC freq from the hypervisor\n");
> + "Failed to setup VMware hypervisor platform\n");
> }
>
> /*
> diff --git a/arch/x86/kernel/x86_init.c b/arch/x86/kernel/x86_init.c
> index cd6da6b..f162e14 100644
> --- a/arch/x86/kernel/x86_init.c
> +++ b/arch/x86/kernel/x86_init.c
> @@ -68,6 +68,7 @@ struct x86_init_ops x86_init __initdata = {
> .setup_percpu_clockev = setup_boot_APIC_clock,
> .tsc_pre_init = x86_init_noop,
> .timer_init = hpet_time_init,
> + .calibrate_apic = native_calibrate_apic
> },
>
> .iommu = {
>

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Next message: Rafael J. Wysocki: "Re: [Bug #16771] [Bisected Regression in 2.6.35] A full tmpfs filesystemcauses hibernationto hang"
Previous message: Mathieu Desnoyers: "[PATCH for -tip] Notifiers: atomic notifier "notrace" call chain"
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