x86: KVM guest: paravirtualized clocksource

	  at the moment), by linking the kernel to a GPL-ed ROM module

	  provided by the hypervisor.

config KVM_CLOCK

	bool "KVM paravirtualized clock"

	select PARAVIRT

	depends on !(X86_VISWS || X86_VOYAGER)

	help

	  Turning on this option will allow you to run a paravirtualized clock

	  when running over the KVM hypervisor. Instead of relying on a PIT

	  (or probably other) emulation by the underlying device model, the host

	  provides the guest with timing infrastructure such as time of day, and

	  system time

source "arch/x86/lguest/Kconfig"

config PARAVIRT

obj-$(CONFIG_DEBUG_NX_TEST)	+= test_nx.o

obj-$(CONFIG_VMI)		+= vmi_32.o vmiclock_32.o

obj-$(CONFIG_KVM_CLOCK)		+= kvmclock.o

obj-$(CONFIG_PARAVIRT)		+= paravirt.o paravirt_patch_$(BITS).o

ifdef CONFIG_INPUT_PCSPKR

/*  KVM paravirtual clock driver. A clocksource implementation

    Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat 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.  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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

*/

#include <linux/clocksource.h>

#include <linux/kvm_para.h>

#include <asm/arch_hooks.h>

#include <asm/msr.h>

#include <asm/apic.h>

#include <linux/percpu.h>

#define KVM_SCALE 22

static int kvmclock = 1;

static int parse_no_kvmclock(char *arg)

{

	kvmclock = 0;

	return 0;

}

early_param("no-kvmclock", parse_no_kvmclock);

/* The hypervisor will put information about time periodically here */

static DEFINE_PER_CPU_SHARED_ALIGNED(struct kvm_vcpu_time_info, hv_clock);

#define get_clock(cpu, field) per_cpu(hv_clock, cpu).field

static inline u64 kvm_get_delta(u64 last_tsc)

{

	int cpu = smp_processor_id();

	u64 delta = native_read_tsc() - last_tsc;

	return (delta * get_clock(cpu, tsc_to_system_mul)) >> KVM_SCALE;

}

static struct kvm_wall_clock wall_clock;

static cycle_t kvm_clock_read(void);

/*

 * The wallclock is the time of day when we booted. Since then, some time may

 * have elapsed since the hypervisor wrote the data. So we try to account for

 * that with system time

 */

unsigned long kvm_get_wallclock(void)

{

	u32 wc_sec, wc_nsec;

	u64 delta;

	struct timespec ts;

	int version, nsec;

	int low, high;

	low = (int)__pa(&wall_clock);

	high = ((u64)__pa(&wall_clock) >> 32);

	delta = kvm_clock_read();

	native_write_msr(MSR_KVM_WALL_CLOCK, low, high);

	do {

		version = wall_clock.wc_version;

		rmb();

		wc_sec = wall_clock.wc_sec;

		wc_nsec = wall_clock.wc_nsec;

		rmb();

	} while ((wall_clock.wc_version != version) || (version & 1));

	delta = kvm_clock_read() - delta;

	delta += wc_nsec;

	nsec = do_div(delta, NSEC_PER_SEC);

	set_normalized_timespec(&ts, wc_sec + delta, nsec);

	/*

	 * Of all mechanisms of time adjustment I've tested, this one

	 * was the champion!

	 */

	return ts.tv_sec + 1;

}

int kvm_set_wallclock(unsigned long now)

{

	return 0;

}

/*

 * This is our read_clock function. The host puts an tsc timestamp each time

 * it updates a new time. Without the tsc adjustment, we can have a situation

 * in which a vcpu starts to run earlier (smaller system_time), but probes

 * time later (compared to another vcpu), leading to backwards time

 */

static cycle_t kvm_clock_read(void)

{

	u64 last_tsc, now;

	int cpu;

	preempt_disable();

	cpu = smp_processor_id();

	last_tsc = get_clock(cpu, tsc_timestamp);

	now = get_clock(cpu, system_time);

	now += kvm_get_delta(last_tsc);

	preempt_enable();

	return now;

}

static struct clocksource kvm_clock = {

	.name = "kvm-clock",

	.read = kvm_clock_read,

	.rating = 400,

	.mask = CLOCKSOURCE_MASK(64),

	.mult = 1 << KVM_SCALE,

	.shift = KVM_SCALE,

	.flags = CLOCK_SOURCE_IS_CONTINUOUS,

};

static int kvm_register_clock(void)

{

	int cpu = smp_processor_id();

	int low, high;

	low = (int)__pa(&per_cpu(hv_clock, cpu)) | 1;

	high = ((u64)__pa(&per_cpu(hv_clock, cpu)) >> 32);

	return native_write_msr_safe(MSR_KVM_SYSTEM_TIME, low, high);

}

static void kvm_setup_secondary_clock(void)

{

	/*

	 * Now that the first cpu already had this clocksource initialized,

	 * we shouldn't fail.

	 */

	WARN_ON(kvm_register_clock());

	/* ok, done with our trickery, call native */

	setup_secondary_APIC_clock();

}

void __init kvmclock_init(void)

{

	if (!kvm_para_available())

		return;

	if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) {

		if (kvm_register_clock())

			return;

		pv_time_ops.get_wallclock = kvm_get_wallclock;

		pv_time_ops.set_wallclock = kvm_set_wallclock;

		pv_time_ops.sched_clock = kvm_clock_read;

		pv_apic_ops.setup_secondary_clock = kvm_setup_secondary_clock;

		clocksource_register(&kvm_clock);

	}

}

#include <linux/pfn.h>

#include <linux/pci.h>

#include <linux/init_ohci1394_dma.h>

#include <linux/kvm_para.h>

#include <video/edid.h>

	max_low_pfn = setup_memory();

#ifdef CONFIG_KVM_CLOCK

	kvmclock_init();

#endif

#ifdef CONFIG_VMI

	/*

	 * Must be after max_low_pfn is determined, and before kernel

#include <linux/ctype.h>

#include <linux/uaccess.h>

#include <linux/init_ohci1394_dma.h>

#include <linux/kvm_para.h>

#include <asm/mtrr.h>

#include <asm/uaccess.h>

	io_delay_init();

#ifdef CONFIG_KVM_CLOCK

	kvmclock_init();

#endif

#ifdef CONFIG_SMP

	/* setup to use the early static init tables during kernel startup */

	x86_cpu_to_apicid_early_ptr = (void *)x86_cpu_to_apicid_init;