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xen: move xen_setup_runstate_info and get_runstate_snapshot to driver…
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…s/xen/time.c

Signed-off-by: Stefano Stabellini <[email protected]>
Acked-by: Ian Campbell <[email protected]>
Reviewed-by: Konrad Rzeszutek Wilk <[email protected]>
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Stefano Stabellini authored and David Vrabel committed Dec 21, 2015
1 parent 4ef7675 commit 4ccefbe
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Showing 4 changed files with 98 additions and 76 deletions.
76 changes: 1 addition & 75 deletions arch/x86/xen/time.c
Original file line number Diff line number Diff line change
Expand Up @@ -32,94 +32,20 @@
#define TIMER_SLOP 100000
#define NS_PER_TICK (1000000000LL / HZ)

/* runstate info updated by Xen */
static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);

/* 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);

/* return an consistent snapshot of 64-bit time/counter value */
static u64 get64(const u64 *p)
{
u64 ret;

if (BITS_PER_LONG < 64) {
u32 *p32 = (u32 *)p;
u32 h, l;

/*
* Read high then low, and then make sure high is
* still the same; this will only loop if low wraps
* and carries into high.
* XXX some clean way to make this endian-proof?
*/
do {
h = p32[1];
barrier();
l = p32[0];
barrier();
} while (p32[1] != h);

ret = (((u64)h) << 32) | l;
} else
ret = *p;

return ret;
}

/*
* Runstate accounting
*/
static void get_runstate_snapshot(struct vcpu_runstate_info *res)
{
u64 state_time;
struct vcpu_runstate_info *state;

BUG_ON(preemptible());

state = this_cpu_ptr(&xen_runstate);

/*
* The runstate info is always updated by the hypervisor on
* the current CPU, so there's no need to use anything
* stronger than a compiler barrier when fetching it.
*/
do {
state_time = get64(&state->state_entry_time);
barrier();
*res = *state;
barrier();
} while (get64(&state->state_entry_time) != state_time);
}

/* return true when a vcpu could run but has no real cpu to run on */
bool xen_vcpu_stolen(int vcpu)
{
return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
}

void xen_setup_runstate_info(int cpu)
{
struct vcpu_register_runstate_memory_area area;

area.addr.v = &per_cpu(xen_runstate, cpu);

if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
cpu, &area))
BUG();
}

static void do_stolen_accounting(void)
{
struct vcpu_runstate_info state;
struct vcpu_runstate_info *snap;
s64 runnable, offline, stolen;
cputime_t ticks;

get_runstate_snapshot(&state);
xen_get_runstate_snapshot(&state);

WARN_ON(state.state != RUNSTATE_running);

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2 changes: 1 addition & 1 deletion drivers/xen/Makefile
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
obj-$(CONFIG_HOTPLUG_CPU) += cpu_hotplug.o
obj-$(CONFIG_X86) += fallback.o
obj-y += grant-table.o features.o balloon.o manage.o preempt.o
obj-y += grant-table.o features.o balloon.o manage.o preempt.o time.o
obj-y += events/
obj-y += xenbus/

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91 changes: 91 additions & 0 deletions drivers/xen/time.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,91 @@
/*
* Xen stolen ticks accounting.
*/
#include <linux/kernel.h>
#include <linux/kernel_stat.h>
#include <linux/math64.h>
#include <linux/gfp.h>

#include <asm/xen/hypervisor.h>
#include <asm/xen/hypercall.h>

#include <xen/events.h>
#include <xen/features.h>
#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
#include <xen/xen-ops.h>

/* runstate info updated by Xen */
static DEFINE_PER_CPU(struct vcpu_runstate_info, xen_runstate);

/* return an consistent snapshot of 64-bit time/counter value */
static u64 get64(const u64 *p)
{
u64 ret;

if (BITS_PER_LONG < 64) {
u32 *p32 = (u32 *)p;
u32 h, l;

/*
* Read high then low, and then make sure high is
* still the same; this will only loop if low wraps
* and carries into high.
* XXX some clean way to make this endian-proof?
*/
do {
h = p32[1];
barrier();
l = p32[0];
barrier();
} while (p32[1] != h);

ret = (((u64)h) << 32) | l;
} else
ret = *p;

return ret;
}

/*
* Runstate accounting
*/
void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
{
u64 state_time;
struct vcpu_runstate_info *state;

BUG_ON(preemptible());

state = this_cpu_ptr(&xen_runstate);

/*
* The runstate info is always updated by the hypervisor on
* the current CPU, so there's no need to use anything
* stronger than a compiler barrier when fetching it.
*/
do {
state_time = get64(&state->state_entry_time);
barrier();
*res = *state;
barrier();
} while (get64(&state->state_entry_time) != state_time);
}

/* return true when a vcpu could run but has no real cpu to run on */
bool xen_vcpu_stolen(int vcpu)
{
return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
}

void xen_setup_runstate_info(int cpu)
{
struct vcpu_register_runstate_memory_area area;

area.addr.v = &per_cpu(xen_runstate, cpu);

if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
cpu, &area))
BUG();
}

5 changes: 5 additions & 0 deletions include/xen/xen-ops.h
Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
#include <linux/notifier.h>
#include <linux/efi.h>
#include <asm/xen/interface.h>
#include <xen/interface/vcpu.h>

DECLARE_PER_CPU(struct vcpu_info *, xen_vcpu);

Expand All @@ -18,6 +19,10 @@ void xen_arch_suspend(void);
void xen_resume_notifier_register(struct notifier_block *nb);
void xen_resume_notifier_unregister(struct notifier_block *nb);

bool xen_vcpu_stolen(int vcpu);
void xen_setup_runstate_info(int cpu);
void xen_get_runstate_snapshot(struct vcpu_runstate_info *res);

int xen_setup_shutdown_event(void);

extern unsigned long *xen_contiguous_bitmap;
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