From mboxrd@z Thu Jan 1 00:00:00 1970 From: Michael Ellerman Subject: Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR Date: Thu, 09 Jul 2020 20:53:16 +1000 Message-ID: <874kqhvu1v.fsf@mpe.ellerman.id.au> References: <20200706043540.1563616-1-npiggin@gmail.com> <20200706043540.1563616-6-npiggin@gmail.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Received: from bilbo.ozlabs.org ([203.11.71.1]:34817 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726339AbgGIKvG (ORCPT ); Thu, 9 Jul 2020 06:51:06 -0400 In-Reply-To: <20200706043540.1563616-6-npiggin@gmail.com> Sender: linux-arch-owner@vger.kernel.org List-ID: To: linuxppc-dev@lists.ozlabs.org Cc: Nicholas Piggin , Will Deacon , Peter Zijlstra , Boqun Feng , Ingo Molnar , Waiman Long , Anton Blanchard , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org Nicholas Piggin writes: > Signed-off-by: Nicholas Piggin > --- > arch/powerpc/include/asm/paravirt.h | 28 ++++++++ > arch/powerpc/include/asm/qspinlock.h | 66 +++++++++++++++++++ > arch/powerpc/include/asm/qspinlock_paravirt.h | 7 ++ > arch/powerpc/platforms/pseries/Kconfig | 5 ++ > arch/powerpc/platforms/pseries/setup.c | 6 +- > include/asm-generic/qspinlock.h | 2 + Another ack? > diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h > index 7a8546660a63..f2d51f929cf5 100644 > --- a/arch/powerpc/include/asm/paravirt.h > +++ b/arch/powerpc/include/asm/paravirt.h > @@ -45,6 +55,19 @@ static inline void yield_to_preempted(int cpu, u32 yield_count) > { > ___bad_yield_to_preempted(); /* This would be a bug */ > } > + > +extern void ___bad_yield_to_any(void); > +static inline void yield_to_any(void) > +{ > + ___bad_yield_to_any(); /* This would be a bug */ > +} Why do we do that rather than just not defining yield_to_any() at all and letting the build fail on that? There's a condition somewhere that we know will false at compile time and drop the call before linking? > diff --git a/arch/powerpc/include/asm/qspinlock_paravirt.h b/arch/powerpc/include/asm/qspinlock_paravirt.h > new file mode 100644 > index 000000000000..750d1b5e0202 > --- /dev/null > +++ b/arch/powerpc/include/asm/qspinlock_paravirt.h > @@ -0,0 +1,7 @@ > +/* SPDX-License-Identifier: GPL-2.0-or-later */ > +#ifndef __ASM_QSPINLOCK_PARAVIRT_H > +#define __ASM_QSPINLOCK_PARAVIRT_H _ASM_POWERPC_QSPINLOCK_PARAVIRT_H please. > + > +EXPORT_SYMBOL(__pv_queued_spin_unlock); Why's that in a header? Should that (eventually) go with the generic implementation? > diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig > index 24c18362e5ea..756e727b383f 100644 > --- a/arch/powerpc/platforms/pseries/Kconfig > +++ b/arch/powerpc/platforms/pseries/Kconfig > @@ -25,9 +25,14 @@ config PPC_PSERIES > select SWIOTLB > default y > > +config PARAVIRT_SPINLOCKS > + bool > + default n default n is the default. > diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c > index 2db8469e475f..747a203d9453 100644 > --- a/arch/powerpc/platforms/pseries/setup.c > +++ b/arch/powerpc/platforms/pseries/setup.c > @@ -771,8 +771,12 @@ static void __init pSeries_setup_arch(void) > if (firmware_has_feature(FW_FEATURE_LPAR)) { > vpa_init(boot_cpuid); > > - if (lppaca_shared_proc(get_lppaca())) > + if (lppaca_shared_proc(get_lppaca())) { > static_branch_enable(&shared_processor); > +#ifdef CONFIG_PARAVIRT_SPINLOCKS > + pv_spinlocks_init(); > +#endif > + } We could avoid the ifdef with this I think? diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 434615f1d761..6ec72282888d 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -10,5 +10,9 @@ #include #endif +#ifndef CONFIG_PARAVIRT_SPINLOCKS +static inline void pv_spinlocks_init(void) { } +#endif + #endif /* __KERNEL__ */ #endif /* __ASM_SPINLOCK_H */ cheers From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bilbo.ozlabs.org ([203.11.71.1]:34817 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726339AbgGIKvG (ORCPT ); Thu, 9 Jul 2020 06:51:06 -0400 From: Michael Ellerman Subject: Re: [PATCH v3 5/6] powerpc/pseries: implement paravirt qspinlocks for SPLPAR In-Reply-To: <20200706043540.1563616-6-npiggin@gmail.com> References: <20200706043540.1563616-1-npiggin@gmail.com> <20200706043540.1563616-6-npiggin@gmail.com> Date: Thu, 09 Jul 2020 20:53:16 +1000 Message-ID: <874kqhvu1v.fsf@mpe.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-arch-owner@vger.kernel.org List-ID: To: Nicholas Piggin , linuxppc-dev@lists.ozlabs.org Cc: Will Deacon , Peter Zijlstra , Boqun Feng , Ingo Molnar , Waiman Long , Anton Blanchard , linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm-ppc@vger.kernel.org, linux-arch@vger.kernel.org Message-ID: <20200709105316.6v_gz5rOaD0Q1Pc3davga0ldcQOdrfT8May51keIcPg@z> Nicholas Piggin writes: > Signed-off-by: Nicholas Piggin > --- > arch/powerpc/include/asm/paravirt.h | 28 ++++++++ > arch/powerpc/include/asm/qspinlock.h | 66 +++++++++++++++++++ > arch/powerpc/include/asm/qspinlock_paravirt.h | 7 ++ > arch/powerpc/platforms/pseries/Kconfig | 5 ++ > arch/powerpc/platforms/pseries/setup.c | 6 +- > include/asm-generic/qspinlock.h | 2 + Another ack? > diff --git a/arch/powerpc/include/asm/paravirt.h b/arch/powerpc/include/asm/paravirt.h > index 7a8546660a63..f2d51f929cf5 100644 > --- a/arch/powerpc/include/asm/paravirt.h > +++ b/arch/powerpc/include/asm/paravirt.h > @@ -45,6 +55,19 @@ static inline void yield_to_preempted(int cpu, u32 yield_count) > { > ___bad_yield_to_preempted(); /* This would be a bug */ > } > + > +extern void ___bad_yield_to_any(void); > +static inline void yield_to_any(void) > +{ > + ___bad_yield_to_any(); /* This would be a bug */ > +} Why do we do that rather than just not defining yield_to_any() at all and letting the build fail on that? There's a condition somewhere that we know will false at compile time and drop the call before linking? > diff --git a/arch/powerpc/include/asm/qspinlock_paravirt.h b/arch/powerpc/include/asm/qspinlock_paravirt.h > new file mode 100644 > index 000000000000..750d1b5e0202 > --- /dev/null > +++ b/arch/powerpc/include/asm/qspinlock_paravirt.h > @@ -0,0 +1,7 @@ > +/* SPDX-License-Identifier: GPL-2.0-or-later */ > +#ifndef __ASM_QSPINLOCK_PARAVIRT_H > +#define __ASM_QSPINLOCK_PARAVIRT_H _ASM_POWERPC_QSPINLOCK_PARAVIRT_H please. > + > +EXPORT_SYMBOL(__pv_queued_spin_unlock); Why's that in a header? Should that (eventually) go with the generic implementation? > diff --git a/arch/powerpc/platforms/pseries/Kconfig b/arch/powerpc/platforms/pseries/Kconfig > index 24c18362e5ea..756e727b383f 100644 > --- a/arch/powerpc/platforms/pseries/Kconfig > +++ b/arch/powerpc/platforms/pseries/Kconfig > @@ -25,9 +25,14 @@ config PPC_PSERIES > select SWIOTLB > default y > > +config PARAVIRT_SPINLOCKS > + bool > + default n default n is the default. > diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c > index 2db8469e475f..747a203d9453 100644 > --- a/arch/powerpc/platforms/pseries/setup.c > +++ b/arch/powerpc/platforms/pseries/setup.c > @@ -771,8 +771,12 @@ static void __init pSeries_setup_arch(void) > if (firmware_has_feature(FW_FEATURE_LPAR)) { > vpa_init(boot_cpuid); > > - if (lppaca_shared_proc(get_lppaca())) > + if (lppaca_shared_proc(get_lppaca())) { > static_branch_enable(&shared_processor); > +#ifdef CONFIG_PARAVIRT_SPINLOCKS > + pv_spinlocks_init(); > +#endif > + } We could avoid the ifdef with this I think? diff --git a/arch/powerpc/include/asm/spinlock.h b/arch/powerpc/include/asm/spinlock.h index 434615f1d761..6ec72282888d 100644 --- a/arch/powerpc/include/asm/spinlock.h +++ b/arch/powerpc/include/asm/spinlock.h @@ -10,5 +10,9 @@ #include #endif +#ifndef CONFIG_PARAVIRT_SPINLOCKS +static inline void pv_spinlocks_init(void) { } +#endif + #endif /* __KERNEL__ */ #endif /* __ASM_SPINLOCK_H */ cheers