Linux Virtualization - Jun 2016 - [PATCH v5 1/6] qspinlock: powerpc support qspinlock

On Thu, 2016-06-02 at 17:22 +0800, Pan Xinhui wrote:
> Base code to enable qspinlock on powerpc. this patch add some #ifdef
> here and there. Although there is no paravirt related code, we can
> successfully build a qspinlock kernel after apply this patch.
This is missing the IO_SYNC stuff ... It means we'll fail to do a full
sync to order vs MMIOs.

You need to add that back in the unlock path.
> Signed-off-by: Pan Xinhui <xinhui.pan at linux.vnet.ibm.com>
> ---
> ?arch/powerpc/include/asm/qspinlock.h??????| 26
> ++++++++++++++++++++++++++
> ?arch/powerpc/include/asm/spinlock.h???????| 27 +++++++++++++++----
> --------
> ?arch/powerpc/include/asm/spinlock_types.h |??4 ++++
> ?arch/powerpc/lib/locks.c??????????????????|??4 ++++
> ?4 files changed, 49 insertions(+), 12 deletions(-)
> ?create mode 100644 arch/powerpc/include/asm/qspinlock.h
> 
> diff --git a/arch/powerpc/include/asm/qspinlock.h
> b/arch/powerpc/include/asm/qspinlock.h
> new file mode 100644
> index 0000000..fc83cd2
> --- /dev/null
> +++ b/arch/powerpc/include/asm/qspinlock.h
> @@ -0,0 +1,26 @@
> +#ifndef _ASM_POWERPC_QSPINLOCK_H
> +#define _ASM_POWERPC_QSPINLOCK_H
> +
> +#include <asm-generic/qspinlock_types.h>
> +
> +#define SPIN_THRESHOLD (1 << 15)
> +#define queued_spin_unlock queued_spin_unlock
> +
> +static inline void native_queued_spin_unlock(struct qspinlock *lock)
> +{
> +	u8 *locked = (u8 *)lock;
> +#ifdef __BIG_ENDIAN
> +	locked += 3;
> +#endif
> +	/* no load/store can be across the unlock()*/
> +	smp_store_release(locked, 0);
> +}
> +
> +static inline void queued_spin_unlock(struct qspinlock *lock)
> +{
> +	native_queued_spin_unlock(lock);
> +}
> +
> +#include <asm-generic/qspinlock.h>
> +
> +#endif /* _ASM_POWERPC_QSPINLOCK_H */
> diff --git a/arch/powerpc/include/asm/spinlock.h
> b/arch/powerpc/include/asm/spinlock.h
> index 523673d..4359ee6 100644
> --- a/arch/powerpc/include/asm/spinlock.h
> +++ b/arch/powerpc/include/asm/spinlock.h
> @@ -52,6 +52,20 @@
> ?#define SYNC_IO
> ?#endif
> ?
> +#if defined(CONFIG_PPC_SPLPAR)
> +/* We only yield to the hypervisor if we are in shared processor
> mode */
> +#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
> >lppaca_ptr))
> +extern void __spin_yield(arch_spinlock_t *lock);
> +extern void __rw_yield(arch_rwlock_t *lock);
> +#else /* SPLPAR */
> +#define __spin_yield(x)	barrier()
> +#define __rw_yield(x)	barrier()
> +#define SHARED_PROCESSOR	0
> +#endif
> +
> +#ifdef CONFIG_QUEUED_SPINLOCKS
> +#include <asm/qspinlock.h>
> +#else
> ?static __always_inline int arch_spin_value_unlocked(arch_spinlock_t
> lock)
> ?{
> ?	return lock.slock == 0;
> @@ -106,18 +120,6 @@ static inline int
> arch_spin_trylock(arch_spinlock_t *lock)
> ? * held.??Conveniently, we have a word in the paca that holds this
> ? * value.
> ? */
> -
> -#if defined(CONFIG_PPC_SPLPAR)
> -/* We only yield to the hypervisor if we are in shared processor
> mode */
> -#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
> >lppaca_ptr))
> -extern void __spin_yield(arch_spinlock_t *lock);
> -extern void __rw_yield(arch_rwlock_t *lock);
> -#else /* SPLPAR */
> -#define __spin_yield(x)	barrier()
> -#define __rw_yield(x)	barrier()
> -#define SHARED_PROCESSOR	0
> -#endif
> -
> ?static inline void arch_spin_lock(arch_spinlock_t *lock)
> ?{
> ?	CLEAR_IO_SYNC;
> @@ -169,6 +171,7 @@ extern void arch_spin_unlock_wait(arch_spinlock_t
> *lock);
> ?	do { while (arch_spin_is_locked(lock)) cpu_relax(); } while
> (0)
> ?#endif
> ?
> +#endif /* !CONFIG_QUEUED_SPINLOCKS */
> ?/*
> ? * Read-write spinlocks, allowing multiple readers
> ? * but only one writer.
> diff --git a/arch/powerpc/include/asm/spinlock_types.h
> b/arch/powerpc/include/asm/spinlock_types.h
> index 2351adc..bd7144e 100644
> --- a/arch/powerpc/include/asm/spinlock_types.h
> +++ b/arch/powerpc/include/asm/spinlock_types.h
> @@ -5,11 +5,15 @@
> ?# error "please don't include this file directly"
> ?#endif
> ?
> +#ifdef CONFIG_QUEUED_SPINLOCKS
> +#include <asm-generic/qspinlock_types.h>
> +#else
> ?typedef struct {
> ?	volatile unsigned int slock;
> ?} arch_spinlock_t;
> ?
> ?#define __ARCH_SPIN_LOCK_UNLOCKED	{ 0 }
> +#endif
> ?
> ?typedef struct {
> ?	volatile signed int lock;
> diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
> index f7deebd..a9ebd71 100644
> --- a/arch/powerpc/lib/locks.c
> +++ b/arch/powerpc/lib/locks.c
> @@ -23,6 +23,7 @@
> ?#include <asm/hvcall.h>
> ?#include <asm/smp.h>
> ?
> +#ifndef CONFIG_QUEUED_SPINLOCKS
> ?void __spin_yield(arch_spinlock_t *lock)
> ?{
> ?	unsigned int lock_value, holder_cpu, yield_count;
> @@ -42,6 +43,7 @@ void __spin_yield(arch_spinlock_t *lock)
> ?		get_hard_smp_processor_id(holder_cpu), yield_count);
> ?}
> ?EXPORT_SYMBOL_GPL(__spin_yield);
> +#endif
> ?
> ?/*
> ? * Waiting for a read lock or a write lock on a rwlock...
> @@ -69,6 +71,7 @@ void __rw_yield(arch_rwlock_t *rw)
> ?}
> ?#endif
> ?
> +#ifndef CONFIG_QUEUED_SPINLOCKS
> ?void arch_spin_unlock_wait(arch_spinlock_t *lock)
> ?{
> ?	smp_mb();
> @@ -84,3 +87,4 @@ void arch_spin_unlock_wait(arch_spinlock_t *lock)
> ?}
> ?
> ?EXPORT_SYMBOL(arch_spin_unlock_wait);
> +#endif

On Fri, 2016-06-03 at 11:32 +1000, Benjamin Herrenschmidt
wrote:
> On Thu, 2016-06-02 at 17:22 +0800, Pan Xinhui wrote:
> > 
> > Base code to enable qspinlock on powerpc. this patch add some
> > #ifdef
> > here and there. Although there is no paravirt related code, we can
> > successfully build a qspinlock kernel after apply this patch.
> This is missing the IO_SYNC stuff ... It means we'll fail to do a
> full
> sync to order vs MMIOs.
> 
> You need to add that back in the unlock path.
Well, and in the lock path as well...

Cheers,
Ben.
> > 
> > Signed-off-by: Pan Xinhui <xinhui.pan at linux.vnet.ibm.com>
> > ---
> > ?arch/powerpc/include/asm/qspinlock.h??????| 26
> > ++++++++++++++++++++++++++
> > ?arch/powerpc/include/asm/spinlock.h???????| 27 +++++++++++++++----
> > --------
> > ?arch/powerpc/include/asm/spinlock_types.h |??4 ++++
> > ?arch/powerpc/lib/locks.c??????????????????|??4 ++++
> > ?4 files changed, 49 insertions(+), 12 deletions(-)
> > ?create mode 100644 arch/powerpc/include/asm/qspinlock.h
> > 
> > diff --git a/arch/powerpc/include/asm/qspinlock.h
> > b/arch/powerpc/include/asm/qspinlock.h
> > new file mode 100644
> > index 0000000..fc83cd2
> > --- /dev/null
> > +++ b/arch/powerpc/include/asm/qspinlock.h
> > @@ -0,0 +1,26 @@
> > +#ifndef _ASM_POWERPC_QSPINLOCK_H
> > +#define _ASM_POWERPC_QSPINLOCK_H
> > +
> > +#include <asm-generic/qspinlock_types.h>
> > +
> > +#define SPIN_THRESHOLD (1 << 15)
> > +#define queued_spin_unlock queued_spin_unlock
> > +
> > +static inline void native_queued_spin_unlock(struct qspinlock
> > *lock)
> > +{
> > +	u8 *locked = (u8 *)lock;
> > +#ifdef __BIG_ENDIAN
> > +	locked += 3;
> > +#endif
> > +	/* no load/store can be across the unlock()*/
> > +	smp_store_release(locked, 0);
> > +}
> > +
> > +static inline void queued_spin_unlock(struct qspinlock *lock)
> > +{
> > +	native_queued_spin_unlock(lock);
> > +}
> > +
> > +#include <asm-generic/qspinlock.h>
> > +
> > +#endif /* _ASM_POWERPC_QSPINLOCK_H */
> > diff --git a/arch/powerpc/include/asm/spinlock.h
> > b/arch/powerpc/include/asm/spinlock.h
> > index 523673d..4359ee6 100644
> > --- a/arch/powerpc/include/asm/spinlock.h
> > +++ b/arch/powerpc/include/asm/spinlock.h
> > @@ -52,6 +52,20 @@
> > ?#define SYNC_IO
> > ?#endif
> > ?
> > +#if defined(CONFIG_PPC_SPLPAR)
> > +/* We only yield to the hypervisor if we are in shared processor
> > mode */
> > +#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
> > > 
> > > lppaca_ptr))
> > +extern void __spin_yield(arch_spinlock_t *lock);
> > +extern void __rw_yield(arch_rwlock_t *lock);
> > +#else /* SPLPAR */
> > +#define __spin_yield(x)	barrier()
> > +#define __rw_yield(x)	barrier()
> > +#define SHARED_PROCESSOR	0
> > +#endif
> > +
> > +#ifdef CONFIG_QUEUED_SPINLOCKS
> > +#include <asm/qspinlock.h>
> > +#else
> > ?static __always_inline int
> > arch_spin_value_unlocked(arch_spinlock_t
> > lock)
> > ?{
> > ?	return lock.slock == 0;
> > @@ -106,18 +120,6 @@ static inline int
> > arch_spin_trylock(arch_spinlock_t *lock)
> > ? * held.??Conveniently, we have a word in the paca that holds this
> > ? * value.
> > ? */
> > -
> > -#if defined(CONFIG_PPC_SPLPAR)
> > -/* We only yield to the hypervisor if we are in shared processor
> > mode */
> > -#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
> > > 
> > > lppaca_ptr))
> > -extern void __spin_yield(arch_spinlock_t *lock);
> > -extern void __rw_yield(arch_rwlock_t *lock);
> > -#else /* SPLPAR */
> > -#define __spin_yield(x)	barrier()
> > -#define __rw_yield(x)	barrier()
> > -#define SHARED_PROCESSOR	0
> > -#endif
> > -
> > ?static inline void arch_spin_lock(arch_spinlock_t *lock)
> > ?{
> > ?	CLEAR_IO_SYNC;
> > @@ -169,6 +171,7 @@ extern void
> > arch_spin_unlock_wait(arch_spinlock_t
> > *lock);
> > ?	do { while (arch_spin_is_locked(lock)) cpu_relax(); }
> > while
> > (0)
> > ?#endif
> > ?
> > +#endif /* !CONFIG_QUEUED_SPINLOCKS */
> > ?/*
> > ? * Read-write spinlocks, allowing multiple readers
> > ? * but only one writer.
> > diff --git a/arch/powerpc/include/asm/spinlock_types.h
> > b/arch/powerpc/include/asm/spinlock_types.h
> > index 2351adc..bd7144e 100644
> > --- a/arch/powerpc/include/asm/spinlock_types.h
> > +++ b/arch/powerpc/include/asm/spinlock_types.h
> > @@ -5,11 +5,15 @@
> > ?# error "please don't include this file directly"
> > ?#endif
> > ?
> > +#ifdef CONFIG_QUEUED_SPINLOCKS
> > +#include <asm-generic/qspinlock_types.h>
> > +#else
> > ?typedef struct {
> > ?	volatile unsigned int slock;
> > ?} arch_spinlock_t;
> > ?
> > ?#define __ARCH_SPIN_LOCK_UNLOCKED	{ 0 }
> > +#endif
> > ?
> > ?typedef struct {
> > ?	volatile signed int lock;
> > diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
> > index f7deebd..a9ebd71 100644
> > --- a/arch/powerpc/lib/locks.c
> > +++ b/arch/powerpc/lib/locks.c
> > @@ -23,6 +23,7 @@
> > ?#include <asm/hvcall.h>
> > ?#include <asm/smp.h>
> > ?
> > +#ifndef CONFIG_QUEUED_SPINLOCKS
> > ?void __spin_yield(arch_spinlock_t *lock)
> > ?{
> > ?	unsigned int lock_value, holder_cpu, yield_count;
> > @@ -42,6 +43,7 @@ void __spin_yield(arch_spinlock_t *lock)
> > ?		get_hard_smp_processor_id(holder_cpu),
> > yield_count);
> > ?}
> > ?EXPORT_SYMBOL_GPL(__spin_yield);
> > +#endif
> > ?
> > ?/*
> > ? * Waiting for a read lock or a write lock on a rwlock...
> > @@ -69,6 +71,7 @@ void __rw_yield(arch_rwlock_t *rw)
> > ?}
> > ?#endif
> > ?
> > +#ifndef CONFIG_QUEUED_SPINLOCKS
> > ?void arch_spin_unlock_wait(arch_spinlock_t *lock)
> > ?{
> > ?	smp_mb();
> > @@ -84,3 +87,4 @@ void arch_spin_unlock_wait(arch_spinlock_t *lock)
> > ?}
> > ?
> > ?EXPORT_SYMBOL(arch_spin_unlock_wait);
> > +#endif

On 2016?06?03? 09:32, Benjamin Herrenschmidt wrote:
> On Fri, 2016-06-03 at 11:32 +1000, Benjamin Herrenschmidt wrote:
>> On Thu, 2016-06-02 at 17:22 +0800, Pan Xinhui wrote:
>>>
>>> Base code to enable qspinlock on powerpc. this patch add some
>>> #ifdef
>>> here and there. Although there is no paravirt related code, we can
>>> successfully build a qspinlock kernel after apply this patch.
>> This is missing the IO_SYNC stuff ... It means we'll fail to do a
>> full
>> sync to order vs MMIOs.
>>
>> You need to add that back in the unlock path.
>
> Well, and in the lock path as well...
>
Oh, yes. I missed IO_SYNC stuff.

thank you, Ben :)
> Cheers,
> Ben.
>
>>>
>>> Signed-off-by: Pan Xinhui <xinhui.pan at linux.vnet.ibm.com>
>>> ---
>>>   arch/powerpc/include/asm/qspinlock.h      | 26
>>> ++++++++++++++++++++++++++
>>>   arch/powerpc/include/asm/spinlock.h       | 27
+++++++++++++++----
>>> --------
>>>   arch/powerpc/include/asm/spinlock_types.h |  4 ++++
>>>   arch/powerpc/lib/locks.c                  |  4 ++++
>>>   4 files changed, 49 insertions(+), 12 deletions(-)
>>>   create mode 100644 arch/powerpc/include/asm/qspinlock.h
>>>
>>> diff --git a/arch/powerpc/include/asm/qspinlock.h
>>> b/arch/powerpc/include/asm/qspinlock.h
>>> new file mode 100644
>>> index 0000000..fc83cd2
>>> --- /dev/null
>>> +++ b/arch/powerpc/include/asm/qspinlock.h
>>> @@ -0,0 +1,26 @@
>>> +#ifndef _ASM_POWERPC_QSPINLOCK_H
>>> +#define _ASM_POWERPC_QSPINLOCK_H
>>> +
>>> +#include <asm-generic/qspinlock_types.h>
>>> +
>>> +#define SPIN_THRESHOLD (1 << 15)
>>> +#define queued_spin_unlock queued_spin_unlock
>>> +
>>> +static inline void native_queued_spin_unlock(struct qspinlock
>>> *lock)
>>> +{
>>> +	u8 *locked = (u8 *)lock;
>>> +#ifdef __BIG_ENDIAN
>>> +	locked += 3;
>>> +#endif
>>> +	/* no load/store can be across the unlock()*/
>>> +	smp_store_release(locked, 0);
>>> +}
>>> +
>>> +static inline void queued_spin_unlock(struct qspinlock *lock)
>>> +{
>>> +	native_queued_spin_unlock(lock);
>>> +}
>>> +
>>> +#include <asm-generic/qspinlock.h>
>>> +
>>> +#endif /* _ASM_POWERPC_QSPINLOCK_H */
>>> diff --git a/arch/powerpc/include/asm/spinlock.h
>>> b/arch/powerpc/include/asm/spinlock.h
>>> index 523673d..4359ee6 100644
>>> --- a/arch/powerpc/include/asm/spinlock.h
>>> +++ b/arch/powerpc/include/asm/spinlock.h
>>> @@ -52,6 +52,20 @@
>>>   #define SYNC_IO
>>>   #endif
>>>
>>> +#if defined(CONFIG_PPC_SPLPAR)
>>> +/* We only yield to the hypervisor if we are in shared processor
>>> mode */
>>> +#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
>>>>
>>>> lppaca_ptr))
>>> +extern void __spin_yield(arch_spinlock_t *lock);
>>> +extern void __rw_yield(arch_rwlock_t *lock);
>>> +#else /* SPLPAR */
>>> +#define __spin_yield(x)	barrier()
>>> +#define __rw_yield(x)	barrier()
>>> +#define SHARED_PROCESSOR	0
>>> +#endif
>>> +
>>> +#ifdef CONFIG_QUEUED_SPINLOCKS
>>> +#include <asm/qspinlock.h>
>>> +#else
>>>   static __always_inline int
>>> arch_spin_value_unlocked(arch_spinlock_t
>>> lock)
>>>   {
>>>   	return lock.slock == 0;
>>> @@ -106,18 +120,6 @@ static inline int
>>> arch_spin_trylock(arch_spinlock_t *lock)
>>>    * held.  Conveniently, we have a word in the paca that holds
this
>>>    * value.
>>>    */
>>> -
>>> -#if defined(CONFIG_PPC_SPLPAR)
>>> -/* We only yield to the hypervisor if we are in shared processor
>>> mode */
>>> -#define SHARED_PROCESSOR (lppaca_shared_proc(local_paca-
>>>>
>>>> lppaca_ptr))
>>> -extern void __spin_yield(arch_spinlock_t *lock);
>>> -extern void __rw_yield(arch_rwlock_t *lock);
>>> -#else /* SPLPAR */
>>> -#define __spin_yield(x)	barrier()
>>> -#define __rw_yield(x)	barrier()
>>> -#define SHARED_PROCESSOR	0
>>> -#endif
>>> -
>>>   static inline void arch_spin_lock(arch_spinlock_t *lock)
>>>   {
>>>   	CLEAR_IO_SYNC;
>>> @@ -169,6 +171,7 @@ extern void
>>> arch_spin_unlock_wait(arch_spinlock_t
>>> *lock);
>>>   	do { while (arch_spin_is_locked(lock)) cpu_relax(); }
>>> while
>>> (0)
>>>   #endif
>>>
>>> +#endif /* !CONFIG_QUEUED_SPINLOCKS */
>>>   /*
>>>    * Read-write spinlocks, allowing multiple readers
>>>    * but only one writer.
>>> diff --git a/arch/powerpc/include/asm/spinlock_types.h
>>> b/arch/powerpc/include/asm/spinlock_types.h
>>> index 2351adc..bd7144e 100644
>>> --- a/arch/powerpc/include/asm/spinlock_types.h
>>> +++ b/arch/powerpc/include/asm/spinlock_types.h
>>> @@ -5,11 +5,15 @@
>>>   # error "please don't include this file directly"
>>>   #endif
>>>
>>> +#ifdef CONFIG_QUEUED_SPINLOCKS
>>> +#include <asm-generic/qspinlock_types.h>
>>> +#else
>>>   typedef struct {
>>>   	volatile unsigned int slock;
>>>   } arch_spinlock_t;
>>>
>>>   #define __ARCH_SPIN_LOCK_UNLOCKED	{ 0 }
>>> +#endif
>>>
>>>   typedef struct {
>>>   	volatile signed int lock;
>>> diff --git a/arch/powerpc/lib/locks.c b/arch/powerpc/lib/locks.c
>>> index f7deebd..a9ebd71 100644
>>> --- a/arch/powerpc/lib/locks.c
>>> +++ b/arch/powerpc/lib/locks.c
>>> @@ -23,6 +23,7 @@
>>>   #include <asm/hvcall.h>
>>>   #include <asm/smp.h>
>>>
>>> +#ifndef CONFIG_QUEUED_SPINLOCKS
>>>   void __spin_yield(arch_spinlock_t *lock)
>>>   {
>>>   	unsigned int lock_value, holder_cpu, yield_count;
>>> @@ -42,6 +43,7 @@ void __spin_yield(arch_spinlock_t *lock)
>>>   		get_hard_smp_processor_id(holder_cpu),
>>> yield_count);
>>>   }
>>>   EXPORT_SYMBOL_GPL(__spin_yield);
>>> +#endif
>>>
>>>   /*
>>>    * Waiting for a read lock or a write lock on a rwlock...
>>> @@ -69,6 +71,7 @@ void __rw_yield(arch_rwlock_t *rw)
>>>   }
>>>   #endif
>>>
>>> +#ifndef CONFIG_QUEUED_SPINLOCKS
>>>   void arch_spin_unlock_wait(arch_spinlock_t *lock)
>>>   {
>>>   	smp_mb();
>>> @@ -84,3 +87,4 @@ void arch_spin_unlock_wait(arch_spinlock_t *lock)
>>>   }
>>>
>>>   EXPORT_SYMBOL(arch_spin_unlock_wait);
>>> +#endif