[Xen-devel] [PATCH v12 4/4] xen/arm: account for stolen ticks

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

Register the runstate_memory_area with the hypervisor.
Use pv_time_ops.steal_clock to account for stolen ticks.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>

---

Changes in v12:
- ifdef CONFIG_PARAVIRT the code that depends on it
- remove useless #include's

Changes in v4:
- don't use paravirt_steal_rq_enabled: we do not support retrieving
stolen ticks for vcpus other than one we are running on.

Changes in v3:
- use BUG_ON and smp_processor_id.
---
 arch/arm/xen/enlighten.c |   24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/arch/arm/xen/enlighten.c b/arch/arm/xen/enlighten.c
index fc7ea52..408211f 100644
--- a/arch/arm/xen/enlighten.c
+++ b/arch/arm/xen/enlighten.c
@@ -79,6 +79,23 @@ int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
 }
 EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
 
+#ifdef CONFIG_PARAVIRT
+#include <asm/paravirt.h>
+
+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];
+}
+#endif
+
 static void xen_percpu_init(void)
 {
        struct vcpu_register_vcpu_info info;
@@ -104,6 +121,8 @@ static void xen_percpu_init(void)
        BUG_ON(err);
        per_cpu(xen_vcpu, cpu) = vcpup;
 
+       xen_setup_runstate_info(cpu);
+
 after_register_vcpu_info:
        enable_percpu_irq(xen_events_irq, 0);
        put_cpu();
@@ -271,6 +290,11 @@ static int __init xen_guest_init(void)
 
        register_cpu_notifier(&xen_cpu_notifier);
 
+#ifdef CONFIG_PARAVIRT
+       pv_time_ops.steal_clock = xen_stolen_accounting;
+       static_key_slow_inc(&paravirt_steal_enabled);
+#endif
+
        return 0;
 }
 early_initcall(xen_guest_init);
-- 
1.7.10.4


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