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Date: Fri, 27 Aug 2010 14:28:51 -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.
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@...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 = {
--
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