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Subject[PATCH 3 of 5] pv clocksource
Hi all,
this adds a PV clocksource that can provide a reliable clocksource for
Linux running as an HVM guest on Xen.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Sheng Yang <sheng@linux.intel.com>

---

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 42135e8..6292cc6 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1253,6 +1253,20 @@ static void __init init_shared_info(void)
per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
}

+static void __init init_pv_clocksource(void)
+{
+ if (!xen_hvm_domain())
+ return;
+
+ pv_time_ops.sched_clock = xen_sched_clock;
+
+ x86_platform.calibrate_tsc = xen_tsc_khz;
+ x86_platform.get_wallclock = xen_get_wallclock;
+ x86_platform.set_wallclock = xen_set_wallclock;
+
+ xen_register_clocksource();
+}
+
void __init xen_guest_init(void)
{
int r;
@@ -1262,5 +1276,6 @@ void __init xen_guest_init(void)
return;

init_shared_info();
+ init_pv_clocksource();
}

diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 0a5aa44..d1c1c50 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -474,11 +474,21 @@ void xen_timer_resume(void)
}
}

+static bool xen_clocksource_enabled;
+
+void xen_register_clocksource(void)
+{
+ if (!xen_clocksource_enabled) {
+ clocksource_register(&xen_clocksource);
+ xen_clocksource_enabled = 1;
+ }
+}
+
__init void xen_time_init(void)
{
int cpu = smp_processor_id();

- clocksource_register(&xen_clocksource);
+ xen_register_clocksource();

if (HYPERVISOR_vcpu_op(VCPUOP_stop_periodic_timer, cpu, NULL) == 0) {
/* Successfully turned off 100Hz tick, so we have the
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index 355fa6b..2aeaf51 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -46,6 +46,7 @@ cycle_t xen_clocksource_read(void);
void xen_setup_cpu_clockevents(void);
unsigned long xen_tsc_khz(void);
void __init xen_time_init(void);
+void xen_register_clocksource(void);
unsigned long xen_get_wallclock(void);
int xen_set_wallclock(unsigned long time);
unsigned long long xen_sched_clock(void);

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