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    SubjectRe: [PATCH] x86, apic: Add apic calibration hook.
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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@vmware.com>
    >
    > 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@vmware.com>
    > Cc: H. Peter Anvin <hpa@zytor.com>
    > ---
    >
    > 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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