commit ecb23dc6f2eff0ce64dd60351a81f376f13b12cc
author Juergen Gross <jgross@suse.com> Fri May 20 09:26:48 2016 +0200
committer David Vrabel <david.vrabel@citrix.com> Wed Jul 06 10:34:48 2016 +0100
tree 09536e5db2dc00af9dd5209fef72a1e1222f6cf2
parent c7ebf9d9c6b4e9402b978da0b0785db4129c1f79

xen: add steal_clock support on x86

The pv_time_ops structure contains a function pointer for the
"steal_clock" functionality used only by KVM and Xen on ARM. Xen on x86
uses its own mechanism to account for the "stolen" time a thread wasn't
able to run due to hypervisor scheduling.

Add support in Xen arch independent time handling for this feature by
moving it out of the arm arch into drivers/xen and remove the x86 Xen
hack.

Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

drivers/xen/time.c

diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 7107842..2257b66 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>
 
@@ -75,6 +76,15 @@
 	return per_cpu(xen_runstate, vcpu).state == RUNSTATE_runnable;
 }
 
+static u64 xen_steal_clock(int cpu)
+{
+	struct vcpu_runstate_info state;
+
+	BUG_ON(cpu != smp_processor_id());
+	xen_get_runstate_snapshot(&state);
+	return state.time[RUNSTATE_runnable] + state.time[RUNSTATE_offline];
+}
+
 void xen_setup_runstate_info(int cpu)
 {
 	struct vcpu_register_runstate_memory_area area;
@@ -86,3 +96,13 @@
 		BUG();
 }
 
+void __init xen_time_setup_guest(void)
+{
+	pv_time_ops.steal_clock = xen_steal_clock;
+
+	static_key_slow_inc(&paravirt_steal_enabled);
+	/*
+	 * We can't set paravirt_steal_rq_enabled as this would require the
+	 * capability to read another cpu's runstate info.
+	 */
+}