RE: [PATCH v4 07/15] x86/paravirt: switch time pvops functions to use static_call()
From: Michael Kelley <hidden>
Date: 2021-01-24 16:16:07
Also in:
kvm, lkml, virtualization, xen-devel
From: Juergen Gross <jgross@suse.com> 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@suse.com> --- 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]
quoted hunk ↗ jump to hunk
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]
quoted hunk ↗ jump to hunk
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