search for: native_virt_spin_lock

...dex 48a706f641f2..fbd98896385c 100644 > --- a/arch/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + > + /* > + * On hypervisors without PARAVIRT_SPINLOCKS support we fall > + * back to a Test-and-Set spinlock, because fair locks have > + * horrible lock 'holder'...

...dex 48a706f641f2..fbd98896385c 100644 > --- a/arch/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + > + /* > + * On hypervisors without PARAVIRT_SPINLOCKS support we fall > + * back to a Test-and-Set spinlock, because fair locks have > + * horrible lock 'holder'...

With virt_spin_lock() being a pvops function the bare metal case can be optimized by patching the call away completely. In case a kernel running as a guest it can decide whether to use paravitualized spinlocks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch

With virt_spin_lock() being a pvops function the bare metal case can be optimized by patching the call away completely. In case a kernel running as a guest it can decide whether to use paravitualized spinlocks, the current fallback to the unfair test-and-set scheme, or to mimic the bare metal behavior. Juergen Gross (4): paravirt: add generic _paravirt_false() function paravirt: switch

...h/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > Should this not have: #ifdef CONFIG_PARAVIRT ? > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + > + /* > + * On hypervisors without PARAVIRT_SPINLOCKS support we fall > + * back to a Test-and-Set spinlock, because fair locks have > + * horrible lock 'holder'...

...h/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > Should this not have: #ifdef CONFIG_PARAVIRT ? > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + > + /* > + * On hypervisors without PARAVIRT_SPINLOCKS support we fall > + * back to a Test-and-Set spinlock, because fair locks have > + * horrible lock 'holder'...

...dex 48a706f641f2..fbd98896385c 100644 > --- a/arch/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + I think you can take the above if statement out as you has done test in native_pv_lock_init(). So the test will also be false here. As this patch series is x86 specific, you should pro...

...dex 48a706f641f2..fbd98896385c 100644 > --- a/arch/x86/include/asm/qspinlock.h > +++ b/arch/x86/include/asm/qspinlock.h > @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) > smp_store_release((u8 *)lock, 0); > } > > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > +{ > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > + return false; > + I think you can take the above if statement out as you has done test in native_pv_lock_init(). So the test will also be false here. As this patch series is x86 specific, you should pro...

...5c 100644 >> --- a/arch/x86/include/asm/qspinlock.h >> +++ b/arch/x86/include/asm/qspinlock.h >> @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) >> smp_store_release((u8 *)lock, 0); >> } >> >> +static inline bool native_virt_spin_lock(struct qspinlock *lock) >> +{ >> + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) >> + return false; >> + >> + /* >> + * On hypervisors without PARAVIRT_SPINLOCKS support we fall >> + * back to a Test-and-Set spinlock, because fair locks have >> + *...

...arch/x86/include/asm/qspinlock.h index 48a706f641f2..fbd98896385c 100644 --- a/arch/x86/include/asm/qspinlock.h +++ b/arch/x86/include/asm/qspinlock.h @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) smp_store_release((u8 *)lock, 0); } +static inline bool native_virt_spin_lock(struct qspinlock *lock) +{ + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) + return false; + + /* + * On hypervisors without PARAVIRT_SPINLOCKS support we fall + * back to a Test-and-Set spinlock, because fair locks have + * horrible lock 'holder' preemption issues. + */ + + do { + whi...

.../arch/x86/include/asm/qspinlock.h >>> +++ b/arch/x86/include/asm/qspinlock.h >>> @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) >>> smp_store_release((u8 *)lock, 0); >>> } >>> >>> +static inline bool native_virt_spin_lock(struct qspinlock *lock) >>> +{ >>> + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) >>> + return false; >>> + >>> + /* >>> + * On hypervisors without PARAVIRT_SPINLOCKS support we fall >>> + * back to a Test-and-Set spinlock, because f...

.../arch/x86/include/asm/qspinlock.h >>> +++ b/arch/x86/include/asm/qspinlock.h >>> @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) >>> smp_store_release((u8 *)lock, 0); >>> } >>> >>> +static inline bool native_virt_spin_lock(struct qspinlock *lock) >>> +{ >>> + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) >>> + return false; >>> + >>> + /* >>> + * On hypervisors without PARAVIRT_SPINLOCKS support we fall >>> + * back to a Test-and-Set spinlock, because f...

On Tue, Sep 05, 2017 at 10:02:57AM -0400, Waiman Long wrote: > On 09/05/2017 09:24 AM, Juergen Gross wrote: > > +static inline bool native_virt_spin_lock(struct qspinlock *lock) > > +{ > > + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) > > + return false; > > + > > I think you can take the above if statement out as you has done test in > native_pv_lock_init(). So the test will also be false here. That does mean we...

...pinlock.h >>>> +++ b/arch/x86/include/asm/qspinlock.h >>>> @@ -17,6 +17,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock) >>>> smp_store_release((u8 *)lock, 0); >>>> } >>>> >>>> +static inline bool native_virt_spin_lock(struct qspinlock *lock) >>>> +{ >>>> + if (!static_cpu_has(X86_FEATURE_HYPERVISOR)) >>>> + return false; >>>> + >>>> + /* >>>> + * On hypervisors without PARAVIRT_SPINLOCKS support we fall >>>> + * back to a Test...