[linux-2.6-block.git] / arch / x86 / kernel / kvmclock.c

/*  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/pvclock.h>
#include <asm/msr.h>
#include <asm/apic.h>
#include <linux/percpu.h>
#include <linux/hardirq.h>
#include <linux/memblock.h>

#include <asm/x86_init.h>
#include <asm/reboot.h>

static int kvmclock = 1;
static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;

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 struct pvclock_vsyscall_time_info *hv_clock;
static struct pvclock_wall_clock wall_clock;

/*
 * 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
 */
static unsigned long kvm_get_wallclock(void)
{
	struct pvclock_vcpu_time_info *vcpu_time;
	struct timespec ts;
	int low, high;
	int cpu;

	low = (int)__pa_symbol(&wall_clock);
	high = ((u64)__pa_symbol(&wall_clock) >> 32);

	native_write_msr(msr_kvm_wall_clock, low, high);

	preempt_disable();
	cpu = smp_processor_id();

	vcpu_time = &hv_clock[cpu].pvti;
	pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);

	preempt_enable();

	return ts.tv_sec;
}

static int kvm_set_wallclock(unsigned long now)
{
	return -1;
}

static cycle_t kvm_clock_read(void)
{
	struct pvclock_vcpu_time_info *src;
	cycle_t ret;
	int cpu;

	preempt_disable_notrace();
	cpu = smp_processor_id();
	src = &hv_clock[cpu].pvti;
	ret = pvclock_clocksource_read(src);
	preempt_enable_notrace();
	return ret;
}

static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
{
	return kvm_clock_read();
}

/*
 * If we don't do that, there is the possibility that the guest
 * will calibrate under heavy load - thus, getting a lower lpj -
 * and execute the delays themselves without load. This is wrong,
 * because no delay loop can finish beforehand.
 * Any heuristics is subject to fail, because ultimately, a large
 * poll of guests can be running and trouble each other. So we preset
 * lpj here
 */
static unsigned long kvm_get_tsc_khz(void)
{
	struct pvclock_vcpu_time_info *src;
	int cpu;
	unsigned long tsc_khz;

	preempt_disable();
	cpu = smp_processor_id();
	src = &hv_clock[cpu].pvti;
	tsc_khz = pvclock_tsc_khz(src);
	preempt_enable();
	return tsc_khz;
}

static void kvm_get_preset_lpj(void)
{
	unsigned long khz;
	u64 lpj;

	khz = kvm_get_tsc_khz();

	lpj = ((u64)khz * 1000);
	do_div(lpj, HZ);
	preset_lpj = lpj;
}

bool kvm_check_and_clear_guest_paused(void)
{
	bool ret = false;
	struct pvclock_vcpu_time_info *src;
	int cpu = smp_processor_id();

	if (!hv_clock)
		return ret;

	src = &hv_clock[cpu].pvti;
	if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
		src->flags &= ~PVCLOCK_GUEST_STOPPED;
		ret = true;
	}

	return ret;
}

static struct clocksource kvm_clock = {
	.name = "kvm-clock",
	.read = kvm_clock_get_cycles,
	.rating = 400,
	.mask = CLOCKSOURCE_MASK(64),
	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
};

int kvm_register_clock(char *txt)
{
	int cpu = smp_processor_id();
	int low, high, ret;
	struct pvclock_vcpu_time_info *src = &hv_clock[cpu].pvti;

	low = (int)__pa(src) | 1;
	high = ((u64)__pa(src) >> 32);
	ret = native_write_msr_safe(msr_kvm_system_time, low, high);
	printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
	       cpu, high, low, txt);

	return ret;
}

static void kvm_save_sched_clock_state(void)
{
}

static void kvm_restore_sched_clock_state(void)
{
	kvm_register_clock("primary cpu clock, resume");
}

#ifdef CONFIG_X86_LOCAL_APIC
static void __cpuinit kvm_setup_secondary_clock(void)
{
	/*
	 * Now that the first cpu already had this clocksource initialized,
	 * we shouldn't fail.
	 */
	WARN_ON(kvm_register_clock("secondary cpu clock"));
}
#endif

/*
 * After the clock is registered, the host will keep writing to the
 * registered memory location. If the guest happens to shutdown, this memory
 * won't be valid. In cases like kexec, in which you install a new kernel, this
 * means a random memory location will be kept being written. So before any
 * kind of shutdown from our side, we unregister the clock by writting anything
 * that does not have the 'enable' bit set in the msr
 */
#ifdef CONFIG_KEXEC
static void kvm_crash_shutdown(struct pt_regs *regs)
{
	native_write_msr(msr_kvm_system_time, 0, 0);
	kvm_disable_steal_time();
	native_machine_crash_shutdown(regs);
}
#endif

static void kvm_shutdown(void)
{
	native_write_msr(msr_kvm_system_time, 0, 0);
	kvm_disable_steal_time();
	native_machine_shutdown();
}

void __init kvmclock_init(void)
{
	unsigned long mem;

	if (!kvm_para_available())
		return;

	if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
		msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
		msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
	} else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
		return;

	printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
		msr_kvm_system_time, msr_kvm_wall_clock);

	mem = memblock_alloc(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS,
			     PAGE_SIZE);
	if (!mem)
		return;
	hv_clock = __va(mem);

	if (kvm_register_clock("boot clock")) {
		hv_clock = NULL;
		memblock_free(mem,
			sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
		return;
	}
	pv_time_ops.sched_clock = kvm_clock_read;
	x86_platform.calibrate_tsc = kvm_get_tsc_khz;
	x86_platform.get_wallclock = kvm_get_wallclock;
	x86_platform.set_wallclock = kvm_set_wallclock;
#ifdef CONFIG_X86_LOCAL_APIC
	x86_cpuinit.early_percpu_clock_init =
		kvm_setup_secondary_clock;
#endif
	x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
	x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
	machine_ops.shutdown  = kvm_shutdown;
#ifdef CONFIG_KEXEC
	machine_ops.crash_shutdown  = kvm_crash_shutdown;
#endif
	kvm_get_preset_lpj();
	clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
	pv_info.paravirt_enabled = 1;
	pv_info.name = "KVM";

	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
		pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
}

int __init kvm_setup_vsyscall_timeinfo(void)
{
#ifdef CONFIG_X86_64
	int cpu;
	int ret;
	u8 flags;
	struct pvclock_vcpu_time_info *vcpu_time;
	unsigned int size;

	size = sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS;

	preempt_disable();
	cpu = smp_processor_id();

	vcpu_time = &hv_clock[cpu].pvti;
	flags = pvclock_read_flags(vcpu_time);

	if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
		preempt_enable();
		return 1;
	}

	if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
		preempt_enable();
		return ret;
	}

	preempt_enable();

	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
#endif
	return 0;
}
Commit	Line	Data
790c73f6 GOC	1	/* KVM paravirtual clock driver. A clocksource implementation
	2	Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
	3
	4	This program is free software; you can redistribute it and/or modify
	5	it under the terms of the GNU General Public License as published by
	6	the Free Software Foundation; either version 2 of the License, or
	7	(at your option) any later version.
	8
	9	This program is distributed in the hope that it will be useful,
	10	but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	GNU General Public License for more details.
	13
	14	You should have received a copy of the GNU General Public License
	15	along with this program; if not, write to the Free Software
	16	Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	17	*/
	18
	19	#include <linux/clocksource.h>
	20	#include <linux/kvm_para.h>
f6e16d5a	21	#include <asm/pvclock.h>
790c73f6 GOC	22	#include <asm/msr.h>
	23	#include <asm/apic.h>
	24	#include <linux/percpu.h>
3b5d56b9	25	#include <linux/hardirq.h>
7069ed67	26	#include <linux/memblock.h>
736decac TG	27
736decac TG	28	#include <asm/x86_init.h>
1e977aa1	29	#include <asm/reboot.h>
790c73f6	30
790c73f6	31	static int kvmclock = 1;
838815a7 GC	32	static int msr_kvm_system_time = MSR_KVM_SYSTEM_TIME;
838815a7 GC	33	static int msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK;
790c73f6 GOC	34
	35	static int parse_no_kvmclock(char *arg)
	36	{
	37	kvmclock = 0;
	38	return 0;
	39	}
	40	early_param("no-kvmclock", parse_no_kvmclock);
	41
	42	/* The hypervisor will put information about time periodically here */
3dc4f7cf	43	static struct pvclock_vsyscall_time_info *hv_clock;
f6e16d5a	44	static struct pvclock_wall_clock wall_clock;
790c73f6	45
790c73f6 GOC	46	/*
	47	* The wallclock is the time of day when we booted. Since then, some time may
	48	* have elapsed since the hypervisor wrote the data. So we try to account for
	49	* that with system time
	50	*/
2ddfd20e	51	static unsigned long kvm_get_wallclock(void)
790c73f6	52	{
f6e16d5a	53	struct pvclock_vcpu_time_info *vcpu_time;
790c73f6	54	struct timespec ts;
790c73f6	55	int low, high;
7069ed67	56	int cpu;
790c73f6	57
a20316d2 GC	58	low = (int)__pa_symbol(&wall_clock);
a20316d2 GC	59	high = ((u64)__pa_symbol(&wall_clock) >> 32);
838815a7 GC	60
838815a7 GC	61	native_write_msr(msr_kvm_wall_clock, low, high);
790c73f6	62
7069ed67 MT	63	preempt_disable();
	64	cpu = smp_processor_id();
	65
3dc4f7cf	66	vcpu_time = &hv_clock[cpu].pvti;
f6e16d5a	67	pvclock_read_wallclock(&wall_clock, vcpu_time, &ts);
7069ed67 MT	68
7069ed67 MT	69	preempt_enable();
790c73f6	70
f6e16d5a	71	return ts.tv_sec;
790c73f6 GOC	72	}
790c73f6 GOC	73
2ddfd20e	74	static int kvm_set_wallclock(unsigned long now)
790c73f6	75	{
f6e16d5a	76	return -1;
790c73f6 GOC	77	}
790c73f6 GOC	78
790c73f6 GOC	79	static cycle_t kvm_clock_read(void)
790c73f6 GOC	80	{
f6e16d5a GH	81	struct pvclock_vcpu_time_info *src;
f6e16d5a GH	82	cycle_t ret;
7069ed67	83	int cpu;
790c73f6	84
95ef1e52	85	preempt_disable_notrace();
7069ed67	86	cpu = smp_processor_id();
3dc4f7cf	87	src = &hv_clock[cpu].pvti;
f6e16d5a	88	ret = pvclock_clocksource_read(src);
95ef1e52	89	preempt_enable_notrace();
f6e16d5a	90	return ret;
790c73f6	91	}
f6e16d5a	92
8e19608e MD	93	static cycle_t kvm_clock_get_cycles(struct clocksource *cs)
	94	{
	95	return kvm_clock_read();
	96	}
	97
0293615f GC	98	/*
	99	* If we don't do that, there is the possibility that the guest
	100	* will calibrate under heavy load - thus, getting a lower lpj -
	101	* and execute the delays themselves without load. This is wrong,
	102	* because no delay loop can finish beforehand.
	103	* Any heuristics is subject to fail, because ultimately, a large
	104	* poll of guests can be running and trouble each other. So we preset
	105	* lpj here
	106	*/
	107	static unsigned long kvm_get_tsc_khz(void)
	108	{
e93353c9	109	struct pvclock_vcpu_time_info *src;
7069ed67 MT	110	int cpu;
	111	unsigned long tsc_khz;
	112
	113	preempt_disable();
	114	cpu = smp_processor_id();
3dc4f7cf	115	src = &hv_clock[cpu].pvti;
7069ed67 MT	116	tsc_khz = pvclock_tsc_khz(src);
	117	preempt_enable();
	118	return tsc_khz;
0293615f GC	119	}
	120
	121	static void kvm_get_preset_lpj(void)
	122	{
0293615f GC	123	unsigned long khz;
	124	u64 lpj;
	125
e93353c9	126	khz = kvm_get_tsc_khz();
0293615f GC	127
	128	lpj = ((u64)khz * 1000);
	129	do_div(lpj, HZ);
	130	preset_lpj = lpj;
	131	}
	132
3b5d56b9 EM	133	bool kvm_check_and_clear_guest_paused(void)
	134	{
	135	bool ret = false;
	136	struct pvclock_vcpu_time_info *src;
7069ed67 MT	137	int cpu = smp_processor_id();
	138
	139	if (!hv_clock)
	140	return ret;
3b5d56b9	141
3dc4f7cf	142	src = &hv_clock[cpu].pvti;
3b5d56b9	143	if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) {
7069ed67	144	src->flags &= ~PVCLOCK_GUEST_STOPPED;
3b5d56b9 EM	145	ret = true;
	146	}
	147
	148	return ret;
	149	}
3b5d56b9	150
790c73f6 GOC	151	static struct clocksource kvm_clock = {
790c73f6 GOC	152	.name = "kvm-clock",
8e19608e	153	.read = kvm_clock_get_cycles,
790c73f6 GOC	154	.rating = 400,
790c73f6 GOC	155	.mask = CLOCKSOURCE_MASK(64),
790c73f6 GOC	156	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
	157	};
	158
ca3f1017	159	int kvm_register_clock(char *txt)
790c73f6 GOC	160	{
790c73f6 GOC	161	int cpu = smp_processor_id();
19b6a85b	162	int low, high, ret;
3dc4f7cf	163	struct pvclock_vcpu_time_info *src = &hv_clock[cpu].pvti;
19b6a85b	164
7069ed67 MT	165	low = (int)__pa(src) \| 1;
7069ed67 MT	166	high = ((u64)__pa(src) >> 32);
19b6a85b	167	ret = native_write_msr_safe(msr_kvm_system_time, low, high);
f6e16d5a GH	168	printk(KERN_INFO "kvm-clock: cpu %d, msr %x:%x, %s\n",
f6e16d5a GH	169	cpu, high, low, txt);
838815a7	170
19b6a85b	171	return ret;
790c73f6 GOC	172	}
790c73f6 GOC	173
b74f05d6 MT	174	static void kvm_save_sched_clock_state(void)
	175	{
	176	}
	177
	178	static void kvm_restore_sched_clock_state(void)
	179	{
	180	kvm_register_clock("primary cpu clock, resume");
	181	}
	182
b8ba5f10	183	#ifdef CONFIG_X86_LOCAL_APIC
23a14b9e	184	static void __cpuinit kvm_setup_secondary_clock(void)
790c73f6 GOC	185	{
	186	/*
	187	* Now that the first cpu already had this clocksource initialized,
	188	* we shouldn't fail.
	189	*/
f6e16d5a	190	WARN_ON(kvm_register_clock("secondary cpu clock"));
790c73f6	191	}
b8ba5f10	192	#endif
790c73f6	193
1e977aa1 GC	194	/*
	195	* After the clock is registered, the host will keep writing to the
	196	* registered memory location. If the guest happens to shutdown, this memory
	197	* won't be valid. In cases like kexec, in which you install a new kernel, this
	198	* means a random memory location will be kept being written. So before any
	199	* kind of shutdown from our side, we unregister the clock by writting anything
	200	* that does not have the 'enable' bit set in the msr
	201	*/
	202	#ifdef CONFIG_KEXEC
	203	static void kvm_crash_shutdown(struct pt_regs *regs)
	204	{
838815a7	205	native_write_msr(msr_kvm_system_time, 0, 0);
d910f5c1	206	kvm_disable_steal_time();
1e977aa1 GC	207	native_machine_crash_shutdown(regs);
	208	}
	209	#endif
	210
	211	static void kvm_shutdown(void)
	212	{
838815a7	213	native_write_msr(msr_kvm_system_time, 0, 0);
d910f5c1	214	kvm_disable_steal_time();
1e977aa1 GC	215	native_machine_shutdown();
	216	}
	217
790c73f6 GOC	218	void __init kvmclock_init(void)
790c73f6 GOC	219	{
7069ed67 MT	220	unsigned long mem;
7069ed67 MT	221
790c73f6 GOC	222	if (!kvm_para_available())
	223	return;
	224
838815a7 GC	225	if (kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
	226	msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
	227	msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
	228	} else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))
	229	return;
	230
	231	printk(KERN_INFO "kvm-clock: Using msrs %x and %x",
	232	msr_kvm_system_time, msr_kvm_wall_clock);
	233
3dc4f7cf	234	mem = memblock_alloc(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS,
7069ed67 MT	235	PAGE_SIZE);
	236	if (!mem)
	237	return;
	238	hv_clock = __va(mem);
	239
	240	if (kvm_register_clock("boot clock")) {
	241	hv_clock = NULL;
	242	memblock_free(mem,
3dc4f7cf	243	sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);
838815a7	244	return;
7069ed67	245	}
838815a7 GC	246	pv_time_ops.sched_clock = kvm_clock_read;
	247	x86_platform.calibrate_tsc = kvm_get_tsc_khz;
	248	x86_platform.get_wallclock = kvm_get_wallclock;
	249	x86_platform.set_wallclock = kvm_set_wallclock;
b8ba5f10	250	#ifdef CONFIG_X86_LOCAL_APIC
df156f90	251	x86_cpuinit.early_percpu_clock_init =
838815a7	252	kvm_setup_secondary_clock;
b8ba5f10	253	#endif
b74f05d6 MT	254	x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
b74f05d6 MT	255	x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
838815a7	256	machine_ops.shutdown = kvm_shutdown;
1e977aa1	257	#ifdef CONFIG_KEXEC
838815a7	258	machine_ops.crash_shutdown = kvm_crash_shutdown;
1e977aa1	259	#endif
838815a7	260	kvm_get_preset_lpj();
b01cc1b0	261	clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
838815a7 GC	262	pv_info.paravirt_enabled = 1;
838815a7 GC	263	pv_info.name = "KVM";
3a0d7256 GC	264
	265	if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
	266	pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
790c73f6	267	}
3dc4f7cf MT	268
	269	int __init kvm_setup_vsyscall_timeinfo(void)
	270	{
	271	#ifdef CONFIG_X86_64
	272	int cpu;
	273	int ret;
	274	u8 flags;
	275	struct pvclock_vcpu_time_info *vcpu_time;
	276	unsigned int size;
	277
	278	size = sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS;
	279
	280	preempt_disable();
	281	cpu = smp_processor_id();
	282
	283	vcpu_time = &hv_clock[cpu].pvti;
	284	flags = pvclock_read_flags(vcpu_time);
	285
	286	if (!(flags & PVCLOCK_TSC_STABLE_BIT)) {
	287	preempt_enable();
	288	return 1;
	289	}
	290
	291	if ((ret = pvclock_init_vsyscall(hv_clock, size))) {
	292	preempt_enable();
	293	return ret;
	294	}
	295
	296	preempt_enable();
	297
	298	kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK;
	299	#endif
	300	return 0;
	301	}