Commit ecb23dc6 authored by Juergen Gross's avatar Juergen Gross Committed by David Vrabel
Browse files

xen: add steal_clock support on x86 



The pv_time_ops structure contains a function pointer for the
"steal_clock" functionality used only by KVM and Xen on ARM. Xen on x86
uses its own mechanism to account for the "stolen" time a thread wasn't
able to run due to hypervisor scheduling.

Add support in Xen arch independent time handling for this feature by
moving it out of the arm arch into drivers/xen and remove the x86 Xen
hack.

Signed-off-by: default avatarJuergen Gross <jgross@suse.com>
Reviewed-by: default avatarBoris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: default avatarStefano Stabellini <sstabellini@kernel.org>
Signed-off-by: default avatarDavid Vrabel <david.vrabel@citrix.com>
parent c7ebf9d9

arch/arm/xen/enlighten.c

+2 −16
Original line number Diff line number Diff line
@@ -12,7 +12,6 @@ 
#include <xen/page.h>

#include <xen/interface/sched.h>

#include <xen/xen-ops.h>

#include <asm/paravirt.h>

#include <asm/xen/hypervisor.h>

#include <asm/xen/hypercall.h>

#include <asm/xen/xen-ops.h>
@@ -86,19 +85,6 @@ int xen_unmap_domain_gfn_range(struct vm_area_struct *vma, 
}

EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);



static unsigned long long xen_stolen_accounting(int cpu)

{

	struct vcpu_runstate_info state;



	BUG_ON(cpu != smp_processor_id());



	xen_get_runstate_snapshot(&state);



	WARN_ON(state.state != RUNSTATE_running);



	return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];

}



static void xen_read_wallclock(struct timespec64 *ts)

{

	u32 version;
@@ -432,8 +418,8 @@ static int __init xen_guest_init(void) 


	register_cpu_notifier(&xen_cpu_notifier);



	pv_time_ops.steal_clock = xen_stolen_accounting;

	static_key_slow_inc(&paravirt_steal_enabled);

	xen_time_setup_guest();



	if (xen_initial_domain())

		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);

arch/x86/xen/time.c

+2 −42
Original line number Diff line number Diff line
@@ -11,8 +11,6 @@ 
#include <linux/interrupt.h>

#include <linux/clocksource.h>

#include <linux/clockchips.h>

#include <linux/kernel_stat.h>

#include <linux/math64.h>

#include <linux/gfp.h>

#include <linux/slab.h>

#include <linux/pvclock_gtod.h>
@@ -31,44 +29,6 @@ 


/* Xen may fire a timer up to this many ns early */

#define TIMER_SLOP	100000

#define NS_PER_TICK	(1000000000LL / HZ)



/* snapshots of runstate info */

static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate_snapshot);



/* unused ns of stolen time */

static DEFINE_PER_CPU(u64, xen_residual_stolen);



static void do_stolen_accounting(void)

{

	struct vcpu_runstate_info state;

	struct vcpu_runstate_info *snap;

	s64 runnable, offline, stolen;

	cputime_t ticks;



	xen_get_runstate_snapshot(&state);



	WARN_ON(state.state != RUNSTATE_running);



	snap = this_cpu_ptr(&xen_runstate_snapshot);



	/* work out how much time the VCPU has not been runn*ing*  */

	runnable = state.time[RUNSTATE_runnable] - snap->time[RUNSTATE_runnable];

	offline = state.time[RUNSTATE_offline] - snap->time[RUNSTATE_offline];



	*snap = state;



	/* Add the appropriate number of ticks of stolen time,

	   including any left-overs from last time. */

	stolen = runnable + offline + __this_cpu_read(xen_residual_stolen);



	if (stolen < 0)

		stolen = 0;



	ticks = iter_div_u64_rem(stolen, NS_PER_TICK, &stolen);

	__this_cpu_write(xen_residual_stolen, stolen);

	account_steal_ticks(ticks);

}



/* Get the TSC speed from Xen */

static unsigned long xen_tsc_khz(void)
@@ -335,8 +295,6 @@ static irqreturn_t xen_timer_interrupt(int irq, void *dev_id) 
		ret = IRQ_HANDLED;

	}



	do_stolen_accounting();



	return ret;

}
@@ -431,6 +389,8 @@ static void __init xen_time_init(void) 
	xen_setup_timer(cpu);

	xen_setup_cpu_clockevents();



	xen_time_setup_guest();



	if (xen_initial_domain())

		pvclock_gtod_register_notifier(&xen_pvclock_gtod_notifier);

}

drivers/xen/time.c

+20 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/math64.h>

#include <linux/gfp.h>



#include <asm/paravirt.h>

#include <asm/xen/hypervisor.h>

#include <asm/xen/hypercall.h>
@@ -75,6 +76,15 @@ bool xen_vcpu_stolen(int vcpu) 
	return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;

}



static u64 xen_steal_clock(int cpu)

{

	struct vcpu_runstate_info state;



	BUG_ON(cpu != smp_processor_id());

	xen_get_runstate_snapshot(&state);

	return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];

}



void xen_setup_runstate_info(int cpu)

{

	struct vcpu_register_runstate_memory_area area;
@@ -86,3 +96,13 @@ void xen_setup_runstate_info(int cpu) 
		BUG();

}



void __init xen_time_setup_guest(void)

{

	pv_time_ops.steal_clock = xen_steal_clock;



	static_key_slow_inc(&paravirt_steal_enabled);

	/*

	 * We can't set paravirt_steal_rq_enabled as this would require the

	 * capability to read another cpu's runstate info.

	 */

}

include/linux/kernel_stat.h

+0 −1
Original line number Diff line number Diff line
@@ -92,7 +92,6 @@ static inline void account_process_tick(struct task_struct *tsk, int user) 
extern void account_process_tick(struct task_struct *, int user);

#endif



extern void account_steal_ticks(unsigned long ticks);

extern void account_idle_ticks(unsigned long ticks);



#endif /* _LINUX_KERNEL_STAT_H */

include/xen/xen-ops.h

+1 −0
Original line number Diff line number Diff line
@@ -21,6 +21,7 @@ void xen_resume_notifier_unregister(struct notifier_block *nb); 


bool xen_vcpu_stolen(int vcpu);

void xen_setup_runstate_info(int cpu);

void xen_time_setup_guest(void);

void xen_get_runstate_snapshot(struct vcpu_runstate_info *res);



int xen_setup_shutdown_event(void);

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