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Commit 409771d2 authored by Stefano Stabellini's avatar Stefano Stabellini Committed by Jeremy Fitzhardinge
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x86: Use xen_vcpuop_clockevent, xen_clocksource and xen wallclock. 



Use xen_vcpuop_clockevent instead of hpet and APIC timers as main
clockevent device on all vcpus, use the xen wallclock time as wallclock
instead of rtc and use xen_clocksource as clocksource.
The pv clock algorithm needs to work correctly for the xen_clocksource
and xen wallclock to be usable, only modern Xen versions offer a
reliable pv clock in HVM guests (XENFEAT_hvm_safe_pvclock).

Using the hpet as clocksource means a VMEXIT every time we read/write to
the hpet mmio addresses, pvclock give us a better rating without
VMEXITs. Same goes for the xen wallclock and xen_vcpuop_clockevent

Signed-off-by: default avatarStefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: default avatarDon Dutile <ddutile@redhat.com>
Signed-off-by: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
parent 99ad198c

arch/x86/xen/enlighten.c

+2 −12
Original line number Diff line number Diff line
@@ -935,10 +935,6 @@ static const struct pv_init_ops xen_init_ops __initdata = { 
	.patch = xen_patch,

};



static const struct pv_time_ops xen_time_ops __initdata = {

	.sched_clock = xen_sched_clock,

};



static const struct pv_cpu_ops xen_cpu_ops __initdata = {

	.cpuid = xen_cpuid,
@@ -1076,7 +1072,6 @@ asmlinkage void __init xen_start_kernel(void) 
	/* Install Xen paravirt ops */

	pv_info = xen_info;

	pv_init_ops = xen_init_ops;

	pv_time_ops = xen_time_ops;

	pv_cpu_ops = xen_cpu_ops;

	pv_apic_ops = xen_apic_ops;
@@ -1084,13 +1079,7 @@ asmlinkage void __init xen_start_kernel(void) 
	x86_init.oem.arch_setup = xen_arch_setup;

	x86_init.oem.banner = xen_banner;



	x86_init.timers.timer_init = xen_time_init;

	x86_init.timers.setup_percpu_clockev = x86_init_noop;

	x86_cpuinit.setup_percpu_clockev = x86_init_noop;



	x86_platform.calibrate_tsc = xen_tsc_khz;

	x86_platform.get_wallclock = xen_get_wallclock;

	x86_platform.set_wallclock = xen_set_wallclock;

	xen_init_time_ops();



	/*

	 * Set up some pagetable state before starting to set any ptes.
@@ -1327,6 +1316,7 @@ static void __init xen_hvm_guest_init(void) 
	register_cpu_notifier(&xen_hvm_cpu_notifier);

	have_vcpu_info_placement = 0;

	x86_init.irqs.intr_init = xen_init_IRQ;

	xen_hvm_init_time_ops();

}



static bool __init xen_hvm_platform(void)

arch/x86/xen/suspend.c

+6 −0
Original line number Diff line number Diff line
@@ -28,8 +28,14 @@ void xen_pre_suspend(void) 


void xen_hvm_post_suspend(int suspend_cancelled)

{

	int cpu;

	xen_hvm_init_shared_info();

	xen_callback_vector();

	if (xen_feature(XENFEAT_hvm_safe_pvclock)) {

		for_each_online_cpu(cpu) {

			xen_setup_runstate_info(cpu);

		}

	}

}



void xen_post_suspend(int suspend_cancelled)

arch/x86/xen/time.c

+53 −5
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <asm/xen/hypercall.h>



#include <xen/events.h>

#include <xen/features.h>

#include <xen/interface/xen.h>

#include <xen/interface/vcpu.h>
@@ -160,7 +161,7 @@ static void do_stolen_accounting(void) 
 * nanoseconds, which is nanoseconds the VCPU spent in RUNNING+BLOCKED

 * states.

 */

unsigned long long xen_sched_clock(void)

static unsigned long long xen_sched_clock(void)

{

	struct vcpu_runstate_info state;

	cycle_t now;
@@ -195,7 +196,7 @@ unsigned long long xen_sched_clock(void) 




/* Get the TSC speed from Xen */

unsigned long xen_tsc_khz(void)

static unsigned long xen_tsc_khz(void)

{

	struct pvclock_vcpu_time_info *info =

		&HYPERVISOR_shared_info->vcpu_info[0].time;
@@ -230,7 +231,7 @@ static void xen_read_wallclock(struct timespec *ts) 
	put_cpu_var(xen_vcpu);

}



unsigned long xen_get_wallclock(void)

static unsigned long xen_get_wallclock(void)

{

	struct timespec ts;
@@ -238,7 +239,7 @@ unsigned long xen_get_wallclock(void) 
	return ts.tv_sec;

}



int xen_set_wallclock(unsigned long now)

static int xen_set_wallclock(unsigned long now)

{

	/* do nothing for domU */

	return -1;
@@ -473,7 +474,11 @@ void xen_timer_resume(void) 
	}

}



__init void xen_time_init(void)

static const struct pv_time_ops xen_time_ops __initdata = {

	.sched_clock = xen_sched_clock,

};



static __init void xen_time_init(void)

{

	int cpu = smp_processor_id();

	struct timespec tp;
@@ -497,3 +502,46 @@ __init void xen_time_init(void) 
	xen_setup_timer(cpu);

	xen_setup_cpu_clockevents();

}



__init void xen_init_time_ops(void)

{

	pv_time_ops = xen_time_ops;



	x86_init.timers.timer_init = xen_time_init;

	x86_init.timers.setup_percpu_clockev = x86_init_noop;

	x86_cpuinit.setup_percpu_clockev = x86_init_noop;



	x86_platform.calibrate_tsc = xen_tsc_khz;

	x86_platform.get_wallclock = xen_get_wallclock;

	x86_platform.set_wallclock = xen_set_wallclock;

}



static void xen_hvm_setup_cpu_clockevents(void)

{

	int cpu = smp_processor_id();

	xen_setup_runstate_info(cpu);

	xen_setup_timer(cpu);

	xen_setup_cpu_clockevents();

}



__init void xen_hvm_init_time_ops(void)

{

	/* vector callback is needed otherwise we cannot receive interrupts

	 * on cpu > 0 */

	if (!xen_have_vector_callback && num_present_cpus() > 1)

		return;

	if (!xen_feature(XENFEAT_hvm_safe_pvclock)) {

		printk(KERN_INFO "Xen doesn't support pvclock on HVM,"

				"disable pv timer\n");

		return;

	}



	pv_time_ops = xen_time_ops;

	x86_init.timers.setup_percpu_clockev = xen_time_init;

	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;



	x86_platform.calibrate_tsc = xen_tsc_khz;

	x86_platform.get_wallclock = xen_get_wallclock;

	x86_platform.set_wallclock = xen_set_wallclock;

}

arch/x86/xen/xen-ops.h

+2 −5
Original line number Diff line number Diff line
@@ -49,11 +49,8 @@ void xen_setup_runstate_info(int cpu); 
void xen_teardown_timer(int cpu);

cycle_t xen_clocksource_read(void);

void xen_setup_cpu_clockevents(void);

unsigned long xen_tsc_khz(void);

void __init xen_time_init(void);

unsigned long xen_get_wallclock(void);

int xen_set_wallclock(unsigned long time);

unsigned long long xen_sched_clock(void);

void __init xen_init_time_ops(void);

void __init xen_hvm_init_time_ops(void);



irqreturn_t xen_debug_interrupt(int irq, void *dev_id);

include/xen/interface/features.h

+3 −0
Original line number Diff line number Diff line
@@ -44,6 +44,9 @@ 
/* x86: Does this Xen host support the HVM callback vector type? */

#define XENFEAT_hvm_callback_vector        8



/* x86: pvclock algorithm is safe to use on HVM */

#define XENFEAT_hvm_safe_pvclock           9



#define XENFEAT_NR_SUBMAPS 1



#endif /* __XEN_PUBLIC_FEATURES_H__ */