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    SubjectRe: [PATCH] x86, apic: Add apic calibration hook.
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    Date
    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 ?

    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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