Re: [PATCH v5 02/12] x86/paravirt: switch time pvops functions to use static_call()

[Jürgen Groß <jgross@xxxxxxxx>]

On 08.03.21 18:00, Boris Ostrovsky wrote:
> On 3/8/21 7:28 AM, Juergen Gross wrote:
> > --- 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.

> >   
> > 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

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