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

From: Alok Kataria
Date: Wed Aug 18 2010 - 15:27:47 EST

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Here is the patch which adds this hook in the x86_init_ops.timers
structure.

---
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>

Index: linux-x86-tree.git/arch/x86/include/asm/apic.h
===================================================================
--- linux-x86-tree.git.orig/arch/x86/include/asm/apic.h 2010-08-17 15:29:21.000000000 -0700
+++ linux-x86-tree.git/arch/x86/include/asm/apic.h 2010-08-17 15:32:11.000000000 -0700
@@ -238,6 +238,7 @@ 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 unsigned int native_calibrate_apic(void);

/*
* On 32bit this is mach-xxx local
Index: linux-x86-tree.git/arch/x86/include/asm/x86_init.h
===================================================================
--- linux-x86-tree.git.orig/arch/x86/include/asm/x86_init.h 2010-08-17 15:29:21.000000000 -0700
+++ linux-x86-tree.git/arch/x86/include/asm/x86_init.h 2010-08-18 12:01:35.000000000 -0700
@@ -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
*/
struct x86_init_timers {
void (*setup_percpu_clockev)(void);
void (*tsc_pre_init)(void);
void (*timer_init)(void);
+ unsigned int (*calibrate_apic)(void);
};

/**
Index: linux-x86-tree.git/arch/x86/kernel/apic/apic.c
===================================================================
--- linux-x86-tree.git.orig/arch/x86/kernel/apic/apic.c 2010-08-17 15:29:21.000000000 -0700
+++ linux-x86-tree.git/arch/x86/kernel/apic/apic.c 2010-08-18 12:05:33.000000000 -0700
@@ -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);
@@ -431,7 +431,7 @@ static void lapic_timer_setup(enum clock
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:
@@ -590,13 +590,46 @@ calibrate_by_pmtimer(long deltapm, long
return 0;
}

+static void __init initialize_lapic_clkevt(long delta)
+{
+ /* 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);
+}
+
static int __init calibrate_APIC_clock(void)
{
+ apic_calibration_res = x86_init.timers.calibrate_apic();
+ if (apic_calibration_res) {
+ struct clock_event_device *levt = &__get_cpu_var(lapic_events);
+ long delta;
+
+ if (lapic_clockevent.mult)
+ return 0;
+
+ delta = (apic_calibration_res * LAPIC_CAL_LOOPS) / APIC_DIVISOR;
+ initialize_lapic_clkevt(delta);
+ levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
+ return 0;
+ } else {
+ pr_warning("Unable to calibrate APIC frequency, "
+ "disabling apic timer\n");
+ return -1;
+ }
+}
+
+unsigned 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();

@@ -631,14 +664,7 @@ static int __init calibrate_APIC_clock(v
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);
-
+ initialize_lapic_clkevt(delta);
calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;

apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
@@ -664,7 +690,7 @@ static int __init calibrate_APIC_clock(v
if (calibration_result < (1000000 / HZ)) {
local_irq_enable();
pr_warning("APIC frequency too slow, disabling apic timer\n");
- return -1;
+ return 0;
}

levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
@@ -706,10 +732,10 @@ static int __init calibrate_APIC_clock(v

if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
pr_warning("APIC timer disabled due to verification failure\n");
- return -1;
+ return 0;
}

- return 0;
+ return calibration_result;
}

/*
Index: linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c
===================================================================
--- linux-x86-tree.git.orig/arch/x86/kernel/cpu/vmware.c 2010-08-17 15:29:21.000000000 -0700
+++ linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c 2010-08-18 12:24:57.000000000 -0700
@@ -72,17 +72,33 @@ static unsigned long vmware_get_tsc_khz(
return tsc_hz;
}

+static unsigned int __init vmware_calibrate_apic(void)
+{
+ unsigned int calibration_result;
+ uint32_t eax, ebx, ecx, edx;
+
+ VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
+ BUG_ON(!ecx);
+ calibration_result = ecx / HZ;
+
+ printk(KERN_INFO "APIC bus freq read from hypervisor : %u.%03u MHz\n",
+ calibration_result / (1000000 / HZ),
+ calibration_result % (1000000 / HZ));
+ return calibration_result;
+}
+
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");
}

/*
Index: linux-x86-tree.git/arch/x86/kernel/x86_init.c
===================================================================
--- linux-x86-tree.git.orig/arch/x86/kernel/x86_init.c 2010-08-17 15:29:21.000000000 -0700
+++ linux-x86-tree.git/arch/x86/kernel/x86_init.c 2010-08-18 12:00:09.000000000 -0700
@@ -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 = {
@@ -95,7 +96,7 @@ struct x86_platform_ops x86_platform = {
.iommu_shutdown = iommu_shutdown_noop,
.is_untracked_pat_range = is_ISA_range,
.nmi_init = default_nmi_init,
- .i8042_detect = default_i8042_detect
+ .i8042_detect = default_i8042_detect,
};

EXPORT_SYMBOL_GPL(x86_platform);

On Wed, 2010-08-18 at 10:41 -0700, Alok Kataria wrote:
> Add a new function pointer calibrate_apic to x86_platform_ops. 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>
>
> Index: linux-x86-tree.git/arch/x86/include/asm/apic.h
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/include/asm/apic.h 2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/include/asm/apic.h 2010-08-17 15:32:11.000000000 -0700
> @@ -238,6 +238,7 @@ 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 unsigned int native_calibrate_apic(void);
>
> /*
> * On 32bit this is mach-xxx local
> Index: linux-x86-tree.git/arch/x86/include/asm/x86_init.h
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/include/asm/x86_init.h 2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/include/asm/x86_init.h 2010-08-18 10:20:21.000000000 -0700
> @@ -143,6 +143,7 @@ struct x86_cpuinit_ops {
> * @is_untracked_pat_range exclude from PAT logic
> * @nmi_init enable NMI on cpus
> * @i8042_detect pre-detect if i8042 controller exists
> + * @calibrate_apic: calibrate APIC bus freq
> */
> struct x86_platform_ops {
> unsigned long (*calibrate_tsc)(void);
> @@ -152,6 +153,7 @@ struct x86_platform_ops {
> bool (*is_untracked_pat_range)(u64 start, u64 end);
> void (*nmi_init)(void);
> int (*i8042_detect)(void);
> + unsigned int (*calibrate_apic)(void);
> };
>
> extern struct x86_init_ops x86_init;
> Index: linux-x86-tree.git/arch/x86/kernel/apic/apic.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/apic/apic.c 2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/apic/apic.c 2010-08-18 10:20:55.000000000 -0700
> @@ -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);
> @@ -431,7 +431,7 @@ static void lapic_timer_setup(enum clock
> 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:
> @@ -590,13 +590,46 @@ calibrate_by_pmtimer(long deltapm, long
> return 0;
> }
>
> +static void __init initialize_lapic_clkevt(long delta)
> +{
> + /* 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);
> +}
> +
> static int __init calibrate_APIC_clock(void)
> {
> + apic_calibration_res = x86_platform.calibrate_apic();
> + if (apic_calibration_res) {
> + struct clock_event_device *levt = &__get_cpu_var(lapic_events);
> + long delta;
> +
> + if (lapic_clockevent.mult)
> + return 0;
> +
> + delta = (apic_calibration_res * LAPIC_CAL_LOOPS) / APIC_DIVISOR;
> + initialize_lapic_clkevt(delta);
> + levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> + return 0;
> + } else {
> + pr_warning("Unable to calibrate APIC frequency, "
> + "disabling apic timer\n");
> + return -1;
> + }
> +}
> +
> +unsigned 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();
>
> @@ -631,14 +664,7 @@ static int __init calibrate_APIC_clock(v
> 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);
> -
> + initialize_lapic_clkevt(delta);
> calibration_result = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS;
>
> apic_printk(APIC_VERBOSE, "..... delta %ld\n", delta);
> @@ -664,7 +690,7 @@ static int __init calibrate_APIC_clock(v
> if (calibration_result < (1000000 / HZ)) {
> local_irq_enable();
> pr_warning("APIC frequency too slow, disabling apic timer\n");
> - return -1;
> + return 0;
> }
>
> levt->features &= ~CLOCK_EVT_FEAT_DUMMY;
> @@ -706,10 +732,10 @@ static int __init calibrate_APIC_clock(v
>
> if (levt->features & CLOCK_EVT_FEAT_DUMMY) {
> pr_warning("APIC timer disabled due to verification failure\n");
> - return -1;
> + return 0;
> }
>
> - return 0;
> + return calibration_result;
> }
>
> /*
> Index: linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/cpu/vmware.c 2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/cpu/vmware.c 2010-08-18 10:20:21.000000000 -0700
> @@ -72,17 +72,33 @@ static unsigned long vmware_get_tsc_khz(
> return tsc_hz;
> }
>
> +static unsigned int vmware_calibrate_apic(void)
> +{
> + unsigned int calibration_result;
> + uint32_t eax, ebx, ecx, edx;
> +
> + VMWARE_PORT(GETHZ, eax, ebx, ecx, edx);
> + BUG_ON(!ecx);
> + calibration_result = ecx / HZ;
> +
> + printk(KERN_INFO "APIC bus freq read from hypervisor : %u.%03u MHz\n",
> + calibration_result / (1000000 / HZ),
> + calibration_result % (1000000 / HZ));
> + return calibration_result;
> +}
> +
> 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_platform.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");
> }
>
> /*
> Index: linux-x86-tree.git/arch/x86/kernel/x86_init.c
> ===================================================================
> --- linux-x86-tree.git.orig/arch/x86/kernel/x86_init.c 2010-08-17 15:29:21.000000000 -0700
> +++ linux-x86-tree.git/arch/x86/kernel/x86_init.c 2010-08-17 16:44:20.000000000 -0700
> @@ -95,7 +95,8 @@ struct x86_platform_ops x86_platform = {
> .iommu_shutdown = iommu_shutdown_noop,
> .is_untracked_pat_range = is_ISA_range,
> .nmi_init = default_nmi_init,
> - .i8042_detect = default_i8042_detect
> + .i8042_detect = default_i8042_detect,
> + .calibrate_apic = native_calibrate_apic
> };
>
> EXPORT_SYMBOL_GPL(x86_platform);
>

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Next message: Arjan van de Ven: "[PATCH] tracing: Make timer tracing actually useful"
Previous message: Andi Kleen: "Re: Proposal: Use hi-res clock for file timestamps"
In reply to: Alok Kataria: "Re: [PATCH] x86, apic: Add apic calibration hook."
Next in thread: Alok Kataria: "Re: [PATCH] x86, apic: Add apic calibration hook."
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]