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Commit 1c7b67f7 authored by Gerd Hoffmann's avatar Gerd Hoffmann Committed by Avi Kivity
Browse files

x86: Make xen use the paravirt clocksource structs and functions 



This patch updates the xen guest to use the pvclock structs
and helper functions.

Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Acked-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 7af192c9

arch/x86/xen/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -5,6 +5,7 @@ 
config XEN

	bool "Xen guest support"

	select PARAVIRT

	select PARAVIRT_CLOCK

	depends on X86_32

	depends on X86_CMPXCHG && X86_TSC && !(X86_VISWS || X86_VOYAGER)

	help

arch/x86/xen/time.c

+12 −120
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ 
#include <linux/kernel_stat.h>

#include <linux/math64.h>



#include <asm/pvclock.h>

#include <asm/xen/hypervisor.h>

#include <asm/xen/hypercall.h>
@@ -31,17 +32,6 @@ 


static cycle_t xen_clocksource_read(void);



/* These are perodically updated in shared_info, and then copied here. */

struct shadow_time_info {

	u64 tsc_timestamp;     /* TSC at last update of time vals.  */

	u64 system_timestamp;  /* Time, in nanosecs, since boot.    */

	u32 tsc_to_nsec_mul;

	int tsc_shift;

	u32 version;

};



static DEFINE_PER_CPU(struct shadow_time_info, shadow_time);



/* runstate info updated by Xen */

static DEFINE_PER_CPU(struct vcpu_runstate_info, runstate);
@@ -211,7 +201,7 @@ unsigned long long xen_sched_clock(void) 
unsigned long xen_cpu_khz(void)

{

	u64 xen_khz = 1000000ULL << 32;

	const struct vcpu_time_info *info =

	const struct pvclock_vcpu_time_info *info =

		&HYPERVISOR_shared_info->vcpu_info[0].time;



	do_div(xen_khz, info->tsc_to_system_mul);
@@ -223,121 +213,26 @@ unsigned long xen_cpu_khz(void) 
	return xen_khz;

}



/*

 * Reads a consistent set of time-base values from Xen, into a shadow data

 * area.

 */

static unsigned get_time_values_from_xen(void)

{

	struct vcpu_time_info   *src;

	struct shadow_time_info *dst;



	/* src is shared memory with the hypervisor, so we need to

	   make sure we get a consistent snapshot, even in the face of

	   being preempted. */

	src = &__get_cpu_var(xen_vcpu)->time;

	dst = &__get_cpu_var(shadow_time);



	do {

		dst->version = src->version;

		rmb();		/* fetch version before data */

		dst->tsc_timestamp     = src->tsc_timestamp;

		dst->system_timestamp  = src->system_time;

		dst->tsc_to_nsec_mul   = src->tsc_to_system_mul;

		dst->tsc_shift         = src->tsc_shift;

		rmb();		/* test version after fetching data */

	} while ((src->version & 1) | (dst->version ^ src->version));



	return dst->version;

}



/*

 * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,

 * yielding a 64-bit result.

 */

static inline u64 scale_delta(u64 delta, u32 mul_frac, int shift)

{

	u64 product;

#ifdef __i386__

	u32 tmp1, tmp2;

#endif



	if (shift < 0)

		delta >>= -shift;

	else

		delta <<= shift;



#ifdef __i386__

	__asm__ (

		"mul  %5       ; "

		"mov  %4,%%eax ; "

		"mov  %%edx,%4 ; "

		"mul  %5       ; "

		"xor  %5,%5    ; "

		"add  %4,%%eax ; "

		"adc  %5,%%edx ; "

		: "=A" (product), "=r" (tmp1), "=r" (tmp2)

		: "a" ((u32)delta), "1" ((u32)(delta >> 32)), "2" (mul_frac) );

#elif __x86_64__

	__asm__ (

		"mul %%rdx ; shrd $32,%%rdx,%%rax"

		: "=a" (product) : "0" (delta), "d" ((u64)mul_frac) );

#else

#error implement me!

#endif



	return product;

}



static u64 get_nsec_offset(struct shadow_time_info *shadow)

{

	u64 now, delta;

	now = native_read_tsc();

	delta = now - shadow->tsc_timestamp;

	return scale_delta(delta, shadow->tsc_to_nsec_mul, shadow->tsc_shift);

}



static cycle_t xen_clocksource_read(void)

{

	struct shadow_time_info *shadow = &get_cpu_var(shadow_time);

        struct pvclock_vcpu_time_info *src;

	cycle_t ret;

	unsigned version;



	do {

		version = get_time_values_from_xen();

		barrier();

		ret = shadow->system_timestamp + get_nsec_offset(shadow);

		barrier();

	} while (version != __get_cpu_var(xen_vcpu)->time.version);



	put_cpu_var(shadow_time);



	src = &get_cpu_var(xen_vcpu)->time;

	ret = pvclock_clocksource_read(src);

	put_cpu_var(xen_vcpu);

	return ret;

}



static void xen_read_wallclock(struct timespec *ts)

{

	const struct shared_info *s = HYPERVISOR_shared_info;

	u32 version;

	u64 delta;

	struct timespec now;



	/* get wallclock at system boot */

	do {

		version = s->wc_version;

		rmb();		/* fetch version before time */

		now.tv_sec  = s->wc_sec;

		now.tv_nsec = s->wc_nsec;

		rmb();		/* fetch time before checking version */

	} while ((s->wc_version & 1) | (version ^ s->wc_version));

	struct shared_info *s = HYPERVISOR_shared_info;

	struct pvclock_wall_clock *wall_clock = &(s->wc);

        struct pvclock_vcpu_time_info *vcpu_time;



	delta = xen_clocksource_read();	/* time since system boot */

	delta += now.tv_sec * (u64)NSEC_PER_SEC + now.tv_nsec;



	now.tv_nsec = do_div(delta, NSEC_PER_SEC);

	now.tv_sec = delta;



	set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);

	vcpu_time = &get_cpu_var(xen_vcpu)->time;

	pvclock_read_wallclock(wall_clock, vcpu_time, ts);

	put_cpu_var(xen_vcpu);

}



unsigned long xen_get_wallclock(void)
@@ -345,7 +240,6 @@ unsigned long xen_get_wallclock(void) 
	struct timespec ts;



	xen_read_wallclock(&ts);



	return ts.tv_sec;

}
@@ -569,8 +463,6 @@ __init void xen_time_init(void) 
{

	int cpu = smp_processor_id();



	get_time_values_from_xen();



	clocksource_register(&xen_clocksource);



	if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) {

include/xen/interface/xen.h

+3 −4
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 
#define __XEN_PUBLIC_XEN_H__



#include <asm/xen/interface.h>

#include <asm/pvclock-abi.h>



/*

 * XEN "SYSTEM CALLS" (a.k.a. HYPERCALLS).
@@ -336,7 +337,7 @@ struct vcpu_info { 
	uint8_t evtchn_upcall_mask;

	unsigned long evtchn_pending_sel;

	struct arch_vcpu_info arch;

	struct vcpu_time_info time;

	struct pvclock_vcpu_time_info time;

}; /* 64 bytes (x86) */



/*
@@ -384,9 +385,7 @@ struct shared_info { 
	 * Wallclock time: updated only by control software. Guests should base

	 * their gettimeofday() syscall on this wallclock-base value.

	 */

	uint32_t wc_version;      /* Version counter: see vcpu_time_info_t. */

	uint32_t wc_sec;          /* Secs  00:00:00 UTC, Jan 1, 1970.  */

	uint32_t wc_nsec;         /* Nsecs 00:00:00 UTC, Jan 1, 1970.  */

	struct pvclock_wall_clock wc;



	struct arch_shared_info arch;