1 files changed, 38 insertions, 12 deletions

diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 71078425c9ea..ac5f23fcafc2 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c
@@ -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>
 
@@ -46,27 +47,31 @@ static u64 get64(const u64 *p)
 	return ret;
 }
 
-/*
- * Runstate accounting
- */
-void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
+static void xen_get_runstate_snapshot_cpu(struct vcpu_runstate_info *res,
+					  unsigned int cpu)
 {
 	u64 state_time;
 	struct vcpu_runstate_info *state;
 
 	BUG_ON(preemptible());
 
-	state = this_cpu_ptr(&xen_runstate);
+	state = per_cpu_ptr(&xen_runstate, cpu);
 
-	/*
-	 * 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);
+		rmb();	/* Hypervisor might update data. */
 		*res = READ_ONCE(*state);
-	} while (get64(&state->state_entry_time) != state_time);
+		rmb();	/* Hypervisor might update data. */
+	} while (get64(&state->state_entry_time) != state_time ||
+		 (state_time & XEN_RUNSTATE_UPDATE));
+}
+
+/*
+ * Runstate accounting
+ */
+void xen_get_runstate_snapshot(struct vcpu_runstate_info *res)
+{
+	xen_get_runstate_snapshot_cpu(res, smp_processor_id());
 }
 
 /* return true when a vcpu could run but has no real cpu to run on */
@@ -75,6 +80,14 @@ bool xen_vcpu_stolen(int vcpu)
 	return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
 }
 
+u64 xen_steal_clock(int cpu)
+{
+	struct vcpu_runstate_info state;
+
+	xen_get_runstate_snapshot_cpu(&state, cpu);
+	return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
+}
+
 void xen_setup_runstate_info(int cpu)
 {
 	struct vcpu_register_runstate_memory_area area;
@@ -82,7 +95,20 @@ void xen_setup_runstate_info(int cpu)
 	area.addr.v = &per_cpu(xen_runstate, cpu);
 
 	if (HYPERVISOR_vcpu_op(VCPUOP_register_runstate_memory_area,
-			       cpu, &area))
+			       xen_vcpu_nr(cpu), &area))
 		BUG();
 }
 
+void __init xen_time_setup_guest(void)
+{
+	bool xen_runstate_remote;
+
+	xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable,
+					VMASST_TYPE_runstate_update_flag);
+
+	pv_time_ops.steal_clock = xen_steal_clock;
+
+	static_key_slow_inc(&paravirt_steal_enabled);
+	if (xen_runstate_remote)
+		static_key_slow_inc(&paravirt_steal_rq_enabled);
+}