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Date: Wed, 01 Sep 2010 12:30:11 -0700 From: Alok Kataria <akataria@...are.com> To: Thomas Gleixner <tglx@...utronix.de> Cc: "H. Peter Anvin" <hpa@...or.com>, the arch/x86 maintainers <x86@...nel.org>, LKML <linux-kernel@...r.kernel.org> Subject: Re: [PATCH] x86, apic: Add apic calibration hook. 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@...are.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@...are.com> > Cc: H. Peter Anvin <hpa@...or.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 = { > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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