On 08.03.21 18:00, Boris Ostrovsky wrote:

On 3/8/21 7:28 AM, Juergen Gross wrote:

quoted

--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c

@@ -379,11 +379,6 @@ void xen_timer_resume(void)
  	}
  }
  
-static const struct pv_time_ops xen_time_ops __initconst = {
-	.sched_clock = xen_sched_clock,
-	.steal_clock = xen_steal_clock,
-};
-
  static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;
  static u64 xen_clock_value_saved;
  

@@ -528,7 +523,8 @@ static void __init xen_time_init(void)
  void __init xen_init_time_ops(void)
  {
  	xen_sched_clock_offset = xen_clocksource_read();
-	pv_ops.time = xen_time_ops;
+	static_call_update(pv_steal_clock, xen_steal_clock);
+	paravirt_set_sched_clock(xen_sched_clock);
  
  	x86_init.timers.timer_init = xen_time_init;
  	x86_init.timers.setup_percpu_clockev = x86_init_noop;

@@ -570,7 +566,8 @@ void __init xen_hvm_init_time_ops(void)
  	}
  
  	xen_sched_clock_offset = xen_clocksource_read();
-	pv_ops.time = xen_time_ops;
+	static_call_update(pv_steal_clock, xen_steal_clock);
+	paravirt_set_sched_clock(xen_sched_clock);
  	x86_init.timers.setup_percpu_clockev = xen_time_init;
  	x86_cpuinit.setup_percpu_clockev = xen_hvm_setup_cpu_clockevents;

There is a bunch of stuff that's common between the two cases so it can be factored out.

Yes.

quoted

diff --git a/drivers/xen/time.c b/drivers/xen/time.c
index 108edbcbc040..152dd33bb223 100644
--- a/drivers/xen/time.c
+++ b/drivers/xen/time.c

@@ -7,6 +7,7 @@
  #include <linux/math64.h>
  #include <linux/gfp.h>
  #include <linux/slab.h>
+#include <linux/static_call.h>
  
  #include <asm/paravirt.h>
  #include <asm/xen/hypervisor.h>

@@ -175,7 +176,7 @@ void __init xen_time_setup_guest(void)
  	xen_runstate_remote = !HYPERVISOR_vm_assist(VMASST_CMD_enable,
  					VMASST_TYPE_runstate_update_flag);
  
-	pv_ops.time.steal_clock = xen_steal_clock;
+	static_call_update(pv_steal_clock, xen_steal_clock);
  

Do we actually need this? We've already set this up in xen_init_time_ops(). (But maybe for ARM).

Correct. Arm needs this.


Juergen