[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] RE: [PATCH v4 07/15] x86/paravirt: switch time pvops functions to use static_call()
From: Juergen Gross <jgross@xxxxxxxx> Sent: Wednesday, January 20, 2021 5:56 AM > > The time pvops functions are the only ones left which might be > used in 32-bit mode and which return a 64-bit value. > > Switch them to use the static_call() mechanism instead of pvops, as > this allows quite some simplification of the pvops implementation. > > Signed-off-by: Juergen Gross <jgross@xxxxxxxx> > --- > V4: > - drop paravirt_time.h again > - don't move Hyper-V code (Michael Kelley) > --- > arch/x86/Kconfig | 1 + > arch/x86/include/asm/mshyperv.h | 2 +- > arch/x86/include/asm/paravirt.h | 17 ++++++++++++++--- > arch/x86/include/asm/paravirt_types.h | 6 ------ > arch/x86/kernel/cpu/vmware.c | 5 +++-- > arch/x86/kernel/kvm.c | 2 +- > arch/x86/kernel/kvmclock.c | 2 +- > arch/x86/kernel/paravirt.c | 16 ++++++++++++---- > arch/x86/kernel/tsc.c | 2 +- > arch/x86/xen/time.c | 11 ++++------- > drivers/clocksource/hyperv_timer.c | 5 +++-- > drivers/xen/time.c | 2 +- > 12 files changed, 42 insertions(+), 29 deletions(-) > [snip] > diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h > index 30f76b966857..b4ee331d29a7 100644 > --- a/arch/x86/include/asm/mshyperv.h > +++ b/arch/x86/include/asm/mshyperv.h > @@ -63,7 +63,7 @@ typedef int (*hyperv_fill_flush_list_func)( > static __always_inline void hv_setup_sched_clock(void *sched_clock) > { > #ifdef CONFIG_PARAVIRT > - pv_ops.time.sched_clock = sched_clock; > + paravirt_set_sched_clock(sched_clock); > #endif > } > This looks fine. [snip] > diff --git a/drivers/clocksource/hyperv_timer.c > b/drivers/clocksource/hyperv_timer.c > index ba04cb381cd3..bf3bf20bc6bd 100644 > --- a/drivers/clocksource/hyperv_timer.c > +++ b/drivers/clocksource/hyperv_timer.c > @@ -18,6 +18,7 @@ > #include <linux/sched_clock.h> > #include <linux/mm.h> > #include <linux/cpuhotplug.h> > +#include <linux/static_call.h> > #include <clocksource/hyperv_timer.h> > #include <asm/hyperv-tlfs.h> > #include <asm/mshyperv.h> > @@ -445,7 +446,7 @@ static bool __init hv_init_tsc_clocksource(void) > clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100); > > hv_sched_clock_offset = hv_read_reference_counter(); > - hv_setup_sched_clock(read_hv_sched_clock_tsc); > + paravirt_set_sched_clock(read_hv_sched_clock_tsc); > > return true; > } > @@ -470,6 +471,6 @@ void __init hv_init_clocksource(void) > clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100); > > hv_sched_clock_offset = hv_read_reference_counter(); > - hv_setup_sched_clock(read_hv_sched_clock_msr); > + static_call_update(pv_sched_clock, read_hv_sched_clock_msr); > } > EXPORT_SYMBOL_GPL(hv_init_clocksource); The changes to hyperv_timer.c aren't needed and shouldn't be there, so as to preserve hyperv_timer.c as architecture neutral. With your update to hv_setup_sched_clock() in mshyperv.h, the original code works correctly. While there are two call sites for hv_setup_sched_clock(), only one is called. And once the sched clock function is set, it is never changed or overridden. Michael
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