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Subject[PATCH 11/13] Use xen_vcpuop_clockevent, xen_clocksource and xen wallclock.
Date
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>

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: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
arch/x86/xen/enlighten.c | 14 +--------
arch/x86/xen/suspend.c | 4 ++
arch/x86/xen/time.c | 59 ++++++++++++++++++++++++++++++++++---
arch/x86/xen/xen-ops.h | 7 +---
include/xen/interface/features.h | 3 ++
5 files changed, 65 insertions(+), 22 deletions(-)
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 90bac21..bcd98a9 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -933,10 +933,6 @@ 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,

@@ -1074,7 +1070,6 @@ 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;

@@ -1082,13 +1077,7 @@ 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.
@@ -1330,4 +1319,5 @@ 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();
}
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 6ff9665..0774c67 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -28,8 +28,12 @@ void xen_pre_suspend(void)

void xen_hvm_post_suspend(int suspend_cancelled)
{
+ int cpu;
xen_hvm_init_shared_info();
xen_callback_vector();
+ for_each_online_cpu(cpu) {
+ xen_setup_runstate_info(cpu);
+ }
}

void xen_post_suspend(int suspend_cancelled)
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 32764b8..2d76c28 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -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();

@@ -497,3 +502,47 @@ __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.timer_init = xen_time_init;
+ x86_init.timers.setup_percpu_clockev = x86_init_noop;
+ 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;
+}
+
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 01c9dd3..089d189 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -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);

diff --git a/include/xen/interface/features.h b/include/xen/interface/features.h
index 8ab08b9..70d2563 100644
--- a/include/xen/interface/features.h
+++ b/include/xen/interface/features.h
@@ -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__ */
--
1.7.0.4


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