The following commit has been merged into the sched/core branch of tip: Commit-ID: 8739c6811572b087decd561f96382087402cc343 Gitweb: https://git.kernel.org/tip/8739c6811572b087decd561f96382087402cc343 Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx> AuthorDate: Thu, 26 Jan 2023 16:08:36 +01:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 31 Jan 2023 15:01:47 +01:00 sched/clock/x86: Mark sched_clock() noinstr In order to use sched_clock() from noinstr code, mark it and all it's implenentations noinstr. The whole pvclock thing (used by KVM/Xen) is a bit of a pain, since it calls out to watchdogs, create a pvclock_clocksource_read_nowd() variant doesn't do that and can be noinstr. Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Link: https://lore.kernel.org/r/20230126151323.702003578@xxxxxxxxxxxxx --- arch/x86/include/asm/kvmclock.h | 2 +- arch/x86/include/asm/paravirt.h | 2 +- arch/x86/include/asm/pvclock.h | 3 ++- arch/x86/kernel/cpu/vmware.c | 2 +- arch/x86/kernel/kvmclock.c | 6 +++--- arch/x86/kernel/pvclock.c | 19 +++++++++++++++---- arch/x86/kernel/tsc.c | 7 +++---- arch/x86/xen/time.c | 12 ++++++++++-- include/linux/math64.h | 4 ++-- 9 files changed, 38 insertions(+), 19 deletions(-) diff --git a/arch/x86/include/asm/kvmclock.h b/arch/x86/include/asm/kvmclock.h index 6c57651..511b350 100644 --- a/arch/x86/include/asm/kvmclock.h +++ b/arch/x86/include/asm/kvmclock.h @@ -8,7 +8,7 @@ extern struct clocksource kvm_clock; DECLARE_PER_CPU(struct pvclock_vsyscall_time_info *, hv_clock_per_cpu); -static inline struct pvclock_vcpu_time_info *this_cpu_pvti(void) +static __always_inline struct pvclock_vcpu_time_info *this_cpu_pvti(void) { return &this_cpu_read(hv_clock_per_cpu)->pvti; } diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h index 86c9d83..cf40e81 100644 --- a/arch/x86/include/asm/paravirt.h +++ b/arch/x86/include/asm/paravirt.h @@ -26,7 +26,7 @@ DECLARE_STATIC_CALL(pv_sched_clock, dummy_sched_clock); void paravirt_set_sched_clock(u64 (*func)(void)); -static inline u64 paravirt_sched_clock(void) +static __always_inline u64 paravirt_sched_clock(void) { return static_call(pv_sched_clock)(); } diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h index 19b695f..0c92db8 100644 --- a/arch/x86/include/asm/pvclock.h +++ b/arch/x86/include/asm/pvclock.h @@ -7,6 +7,7 @@ /* some helper functions for xen and kvm pv clock sources */ u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src); +u64 pvclock_clocksource_read_nowd(struct pvclock_vcpu_time_info *src); u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src); void pvclock_set_flags(u8 flags); unsigned long pvclock_tsc_khz(struct pvclock_vcpu_time_info *src); @@ -39,7 +40,7 @@ bool pvclock_read_retry(const struct pvclock_vcpu_time_info *src, * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction, * yielding a 64-bit result. */ -static inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift) +static __always_inline u64 pvclock_scale_delta(u64 delta, u32 mul_frac, int shift) { u64 product; #ifdef __i386__ diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c index 02039ec..11f83d0 100644 --- a/arch/x86/kernel/cpu/vmware.c +++ b/arch/x86/kernel/cpu/vmware.c @@ -143,7 +143,7 @@ static __init int parse_no_stealacc(char *arg) } early_param("no-steal-acc", parse_no_stealacc); -static unsigned long long notrace vmware_sched_clock(void) +static noinstr u64 vmware_sched_clock(void) { unsigned long long ns; diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 16333ba..0f35d44 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -71,12 +71,12 @@ static int kvm_set_wallclock(const struct timespec64 *now) return -ENODEV; } -static u64 kvm_clock_read(void) +static noinstr u64 kvm_clock_read(void) { u64 ret; preempt_disable_notrace(); - ret = pvclock_clocksource_read(this_cpu_pvti()); + ret = pvclock_clocksource_read_nowd(this_cpu_pvti()); preempt_enable_notrace(); return ret; } @@ -86,7 +86,7 @@ static u64 kvm_clock_get_cycles(struct clocksource *cs) return kvm_clock_read(); } -static u64 kvm_sched_clock_read(void) +static noinstr u64 kvm_sched_clock_read(void) { return kvm_clock_read() - kvm_sched_clock_offset; } diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c index 5a2a517..56acf53 100644 --- a/arch/x86/kernel/pvclock.c +++ b/arch/x86/kernel/pvclock.c @@ -64,7 +64,8 @@ u8 pvclock_read_flags(struct pvclock_vcpu_time_info *src) return flags & valid_flags; } -u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) +static __always_inline +u64 __pvclock_clocksource_read(struct pvclock_vcpu_time_info *src, bool dowd) { unsigned version; u64 ret; @@ -77,7 +78,7 @@ u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) flags = src->flags; } while (pvclock_read_retry(src, version)); - if (unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) { + if (dowd && unlikely((flags & PVCLOCK_GUEST_STOPPED) != 0)) { src->flags &= ~PVCLOCK_GUEST_STOPPED; pvclock_touch_watchdogs(); } @@ -100,15 +101,25 @@ u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) * updating at the same time, and one of them could be slightly behind, * making the assumption that last_value always go forward fail to hold. */ - last = atomic64_read(&last_value); + last = arch_atomic64_read(&last_value); do { if (ret <= last) return last; - } while (!atomic64_try_cmpxchg(&last_value, &last, ret)); + } while (!arch_atomic64_try_cmpxchg(&last_value, &last, ret)); return ret; } +u64 pvclock_clocksource_read(struct pvclock_vcpu_time_info *src) +{ + return __pvclock_clocksource_read(src, true); +} + +noinstr u64 pvclock_clocksource_read_nowd(struct pvclock_vcpu_time_info *src) +{ + return __pvclock_clocksource_read(src, false); +} + void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock, struct pvclock_vcpu_time_info *vcpu_time, struct timespec64 *ts) diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index a78e73d..8c33936 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -215,7 +215,7 @@ static void __init cyc2ns_init_secondary_cpus(void) /* * Scheduler clock - returns current time in nanosec units. */ -u64 native_sched_clock(void) +noinstr u64 native_sched_clock(void) { if (static_branch_likely(&__use_tsc)) { u64 tsc_now = rdtsc(); @@ -248,7 +248,7 @@ u64 native_sched_clock_from_tsc(u64 tsc) /* We need to define a real function for sched_clock, to override the weak default version */ #ifdef CONFIG_PARAVIRT -unsigned long long sched_clock(void) +noinstr u64 sched_clock(void) { return paravirt_sched_clock(); } @@ -258,8 +258,7 @@ bool using_native_sched_clock(void) return static_call_query(pv_sched_clock) == native_sched_clock; } #else -unsigned long long -sched_clock(void) __attribute__((alias("native_sched_clock"))); +u64 sched_clock(void) __attribute__((alias("native_sched_clock"))); bool using_native_sched_clock(void) { return true; } #endif diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 9ef0a5c..6b8836d 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -60,9 +60,17 @@ static u64 xen_clocksource_get_cycles(struct clocksource *cs) return xen_clocksource_read(); } -static u64 xen_sched_clock(void) +static noinstr u64 xen_sched_clock(void) { - return xen_clocksource_read() - xen_sched_clock_offset; + struct pvclock_vcpu_time_info *src; + u64 ret; + + preempt_disable_notrace(); + src = &__this_cpu_read(xen_vcpu)->time; + ret = pvclock_clocksource_read_nowd(src); + ret -= xen_sched_clock_offset; + preempt_enable_notrace(); + return ret; } static void xen_read_wallclock(struct timespec64 *ts) diff --git a/include/linux/math64.h b/include/linux/math64.h index 8958f4c..8b9191a 100644 --- a/include/linux/math64.h +++ b/include/linux/math64.h @@ -161,7 +161,7 @@ static inline u64 mul_u32_u32(u32 a, u32 b) #if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__) #ifndef mul_u64_u32_shr -static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) +static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) { return (u64)(((unsigned __int128)a * mul) >> shift); } @@ -177,7 +177,7 @@ static inline u64 mul_u64_u64_shr(u64 a, u64 mul, unsigned int shift) #else #ifndef mul_u64_u32_shr -static inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) +static __always_inline u64 mul_u64_u32_shr(u64 a, u32 mul, unsigned int shift) { u32 ah, al; u64 ret;
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