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

Jürgen Groß
2021-03-09T06:15:42Z

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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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