Re: + stupid-hack-to-make-mainline-build.patch added to -mm tree

Dan Hecht
2007-03-07T19:54:16Z

On 03/07/2007 11:05 AM, Jeremy Fitzhardinge wrote:
> James Morris wrote:
>> It seems to me that it could be useful to have a library of common virtual
>> time code (entirely separate from pv_ops), to avoid re-implementing some
>> apparently common requirements, such as: handling TSC frequency changes,
>> stolen time accounting, synthetic programmable clockevent etc.
>>
>
> Well, lets put our clock* implementations next to each other and see how
> much common code there is to be factored out.
>
> The Xen time code is pretty lean. There's not much difference in
> abstraction between the clocksource/event interface and the hypervisor
> interface, so there's just not very much code there.
>

Jeremy, I saw you sent out the Xen version earlier, thanks. Here's ours
for reference (please excuse any formating issues); it's also lean.
We'll send out a proper patch later after some more testing:

---

/*
* VMI paravirtual timer support routines.
*
* Copyright (C) 2007, VMware, Inc.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*/

#include <linux/smp.h>
#include <linux/cpumask.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>

#include <asm/vmi.h>
#include <asm/vmi_time.h>
#include <asm/apic.h>
#include <asm/i8253.h>
#include <asm/arch_hooks.h>

#include <irq_vectors.h>

#define VMI_ONESHOT (VMI_ALARM_IS_ONESHOT | VMI_CYCLES_REAL)
#define VMI_PERIODIC (VMI_ALARM_IS_PERIODIC | VMI_CYCLES_REAL)

static inline u32 vmi_counter(u32 flags)
{
/* Given VMI_ONESHOT or VMI_PERIODIC, return the corresponding
* cycle counter. */
return flags & VMI_ALARM_COUNTER_MASK;
}

/* paravirt_ops.get_wallclock = vmi_get_wallclock */
unsigned long vmi_get_wallclock(void)
{
unsigned long long wallclock;
wallclock = vmi_timer_ops.get_wallclock(); // nsec
(void)do_div(wallclock, 1000000000); // sec

return wallclock;
}

/* paravirt_ops.set_wallclock = vmi_set_wallclock */
int vmi_set_wallclock(unsigned long now)
{
return 0;
}

/* paravirt_ops.get_scheduled_cycles = vmi_get_sched_cycles */
unsigned long long vmi_get_sched_cycles(void)
{
return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_AVAILABLE);
}

/* paravirt_ops.get_cpu_khz = vmi_cpu_khz */
unsigned long vmi_cpu_khz(void)
{
unsigned long long khz;
khz = vmi_timer_ops.get_cycle_frequency();
(void)do_div(khz, 1000);
return khz;
}

/** vmi clockevent */

static struct clock_event_device vmi_global_clockevent;

static inline u32 vmi_alarm_wiring(struct clock_event_device *evt)
{
return (evt == &vmi_global_clockevent) ?
VMI_ALARM_WIRED_IRQ0 : VMI_ALARM_WIRED_LVTT;
}

static void vmi_timer_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
u32 wiring;
cycle_t now, cycles_per_hz;
BUG_ON(!irqs_disabled());

wiring = vmi_alarm_wiring(evt);
if (wiring == VMI_ALARM_WIRED_LVTT)
/* Route the interrupt to the correct vector */
apic_write_around(APIC_LVTT, LOCAL_TIMER_VECTOR);

switch (mode) {
case CLOCK_EVT_MODE_ONESHOT:
break;
case CLOCK_EVT_MODE_PERIODIC:
cycles_per_hz = vmi_timer_ops.get_cycle_frequency();
(void)do_div(cycles_per_hz, HZ);
now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_PERIODIC));
vmi_timer_ops.set_alarm(wiring | VMI_PERIODIC,
now, cycles_per_hz);
break;
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_SHUTDOWN:
switch (evt->mode) {
case CLOCK_EVT_MODE_ONESHOT:
vmi_timer_ops.cancel_alarm(VMI_ONESHOT);
break;
case CLOCK_EVT_MODE_PERIODIC:
vmi_timer_ops.cancel_alarm(VMI_PERIODIC);
break;
default:
break;
}
break;
default:
break;
}
}

static int vmi_timer_next_event(unsigned long delta,
struct clock_event_device *evt)
{
/* Unfortunately, set_next_event interface only passes relative
* expiry, but we want absolute expiry. It'd be better if were
* were passed an aboslute expiry, since a bunch of time may
* have been stolen between the time the delta is computed and
* when we set the alarm below. */
cycle_t now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_ONESHOT));

BUG_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
vmi_timer_ops.set_alarm(vmi_alarm_wiring(evt) | VMI_ONESHOT,
now + delta, 0);
return 0;
}

static struct clock_event_device vmi_clockevent = {
.name = "vmi-timer",
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.shift = 22,
.set_mode = vmi_timer_set_mode,
.set_next_event = vmi_timer_next_event,
.rating = 1000,
.irq = -1,
};

/* Replacement for PIT/HPET global clock event.
* paravirt_ops.choose_time_init = vmi_time_init_clockevent
*/
void __init vmi_time_init_clockevent(void)
{
cycle_t cycles_per_msec;

/* One time setup: initialize the vmi clockevent parameters.
* These will be copied to the global and local clockevents. */

/* Use cycles_per_msec since div_sc params are 32-bits. */
cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
(void)do_div(cycles_per_msec, 1000);

/* Must pick .shift such that .mult fits in 32-bits. Choosing
* .shift to be 22 allows 2^(32-22) cycles per nano-seconds
* before overflow. */
vmi_clockevent.mult = div_sc(cycles_per_msec, NSEC_PER_MSEC,
vmi_clockevent.shift);
/* Upper bound is clockevent's use of ulong for cycle deltas. */
vmi_clockevent.max_delta_ns =
clockevent_delta2ns(ULONG_MAX, &vmi_clockevent);
vmi_clockevent.min_delta_ns =
clockevent_delta2ns(1, &vmi_clockevent);

memcpy(&vmi_global_clockevent, &vmi_clockevent,
sizeof(vmi_global_clockevent));
vmi_global_clockevent.name = "vmi-timer (boot)";
vmi_global_clockevent.cpumask = cpumask_of_cpu(0);
vmi_global_clockevent.irq = 0;

printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu
shift=%u\n",
vmi_global_clockevent.name, vmi_global_clockevent.mult,
vmi_global_clockevent.shift);
clockevents_register_device(&vmi_global_clockevent);
global_clock_event = &vmi_global_clockevent;

/* We use normal irq0 handler on cpu0. */
time_init_hook();
}

#ifdef CONFIG_X86_LOCAL_APIC

/* Replacement for lapic timer local clock event.
* paravirt_ops.setup_boot_clock = vmi_nop
* (continue using global_clock_event on cpu0)
* paravirt_ops.setup_secondary_clock = vmi_timer_setup_local_alarm
*/
void __devinit vmi_timer_setup_local_alarm(void)
{
struct clock_event_device *evt = &__get_cpu_var(local_clock_events);

/* Then, start it back up as a local clockevent device. */
memcpy(evt, &vmi_clockevent, sizeof(*evt));
evt->cpumask = cpumask_of_cpu(smp_processor_id());

printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu
shift=%u\n",
evt->name, evt->mult, evt->shift);
clockevents_register_device(evt);
}

#endif

/** vmi clocksource */

static cycle_t read_real_cycles(void)
{
return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
}

static struct clocksource clocksource_vmi = {
.name = "vmi-timer",
.rating = 450,
.read = read_real_cycles,
.mask = CLOCKSOURCE_MASK(64),
.mult = 0, /* to be set */
.shift = 22,
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};

static int __init init_vmi_clocksource(void)
{
cycle_t cycles_per_msec;

if (!vmi_timer_ops.get_cycle_frequency)
return 0;
/* Use khz2mult rather than hz2mult since hz arg is only 32-bits. */
cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
(void)do_div(cycles_per_msec, 1000);

/* Note that clocksource.{mult, shift} converts in the opposite direction
* as clockevents. */
clocksource_vmi.mult = clocksource_khz2mult(cycles_per_msec,
clocksource_vmi.shift);

printk(KERN_WARNING "vmi: registering clock source khz=%lld\n",
cycles_per_msec);
return clocksource_register(&clocksource_vmi);

}
module_init(init_vmi_clocksource);