From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1BF12C433E0 for ; Thu, 9 Jul 2020 10:51:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E69F92074B for ; Thu, 9 Jul 2020 10:51:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ellerman.id.au header.i=@ellerman.id.au header.b="IKD2ten4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726606AbgGIKvG (ORCPT ); Thu, 9 Jul 2020 06:51:06 -0400 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 Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mail.ozlabs.org (Postfix) with ESMTPSA id 4B2Xyv3zTwz9sQt; Thu, 9 Jul 2020 20:51:03 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ellerman.id.au; s=201909; t=1594291864; bh=VI4aFN/tvbsGFEJ4xA4/0VeUoMRZZnfq/gpr3pAx8G0=; h=From:To:Cc:Subject:In-Reply-To:References:Date:From; b=IKD2ten4BhzVwExubvn3K93mtWqnC3WWAZoRzc+c3H8YbG4WdsqsYIsWtHE7Mr0GH nGpjcBK6Dan3kZ/RMkJ8HleBBVOarl2j8GlhAGagpMFmLzOUokO9woJyZe4KB9Tvwf 0gHMuKiiBQ3KcLbW84Ee0saFgPCykKlyofIbboYWIBK9RSlMTJJFeFiEwRu+zC4apq bE4ngiBaxW+gJCjWBfPK2R/oK0LL8F7QhMQriTR0TsdOezFACf1z9JYBLvElvotO+B y9apR0IOzs3WlCA9v8OvGe3t3FZaAfE4Haq+4aFUFiz6O2rlfWYCuDwrQiPGASWc69 zr4ZnuPJOXulA== From: Michael Ellerman To: Nicholas Piggin , 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 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-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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