From patchwork Wed Aug 2 16:46:54 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 13338537 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 30B53C04FDF for ; Wed, 2 Aug 2023 16:51:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229987AbjHBQvw (ORCPT ); Wed, 2 Aug 2023 12:51:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233215AbjHBQvZ (ORCPT ); Wed, 2 Aug 2023 12:51:25 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8762830ED; Wed, 2 Aug 2023 09:50:56 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id E8EAE61A43; Wed, 2 Aug 2023 16:50:55 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C843C433C8; Wed, 2 Aug 2023 16:50:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1690995055; bh=Ex6OYX3JGNnUHd85CnRKWsm8lmD+bGAwdtplvxxj8PY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=um7BNA7itHG6dHP1/TJ2qBnWLjq8LpHkLPRfh1qtGRbNzY7ZAXLFTcYLA+tJ6mLLP jKEjkHopqqvN+oHeq15IcuNa1QsUbkSzrWjKAT649fqQW0PuY/YQ88ATN23zqp/W/7 ThJSk6zBrbelucVEcgJ2wvGt3ZI1/ZpuTm/yvaQP8PajaVwGcVRMnHlM+LlFwPd9XO uQwO0jbLuHeszx11KXEt6scpahkYLC+c19wzJR8sVOlcF/PbRo/yUHnKdSgpxrwXmH 3zvGNqg+OtbF1LKbaLWUWXqGWaXGQEWygJ9D7So5hpuqI7YGXBR91UK6+tb74VvBC9 Hz1m3QjgRrJ+Q== From: guoren@kernel.org To: paul.walmsley@sifive.com, anup@brainfault.org, peterz@infradead.org, mingo@redhat.com, will@kernel.org, palmer@rivosinc.com, longman@redhat.com, boqun.feng@gmail.com, tglx@linutronix.de, paulmck@kernel.org, rostedt@goodmis.org, rdunlap@infradead.org, catalin.marinas@arm.com, conor.dooley@microchip.com, xiaoguang.xing@sophgo.com, bjorn@rivosinc.com, alexghiti@rivosinc.com, keescook@chromium.org, greentime.hu@sifive.com, ajones@ventanamicro.com, jszhang@kernel.org, wefu@redhat.com, wuwei2016@iscas.ac.cn Cc: linux-arch@vger.kernel.org, linux-riscv@lists.infradead.org, linux-doc@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-csky@vger.kernel.org, Guo Ren , Guo Ren Subject: [PATCH V10 12/19] RISC-V: paravirt: pvqspinlock: Add nopvspin kernel parameter Date: Wed, 2 Aug 2023 12:46:54 -0400 Message-Id: <20230802164701.192791-13-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 In-Reply-To: <20230802164701.192791-1-guoren@kernel.org> References: <20230802164701.192791-1-guoren@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Guo Ren Disables the qspinlock slow path using PV optimizations which allow the hypervisor to 'idle' the guest on lock contention. Signed-off-by: Guo Ren Signed-off-by: Guo Ren --- Documentation/admin-guide/kernel-parameters.txt | 2 +- arch/riscv/kernel/paravirt.c | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index de6b7ee752cd..1a8878f6bfbd 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3820,7 +3820,7 @@ as generic guest with no PV drivers. Currently support XEN HVM, KVM, HYPER_V and VMWARE guest. - nopvspin [X86,XEN,KVM] + nopvspin [X86,XEN,KVM,RISC-V] Disables the qspinlock slow path using PV optimizations which allow the hypervisor to 'idle' the guest on lock contention. diff --git a/arch/riscv/kernel/paravirt.c b/arch/riscv/kernel/paravirt.c index 1bacb2cf3872..b55c3d3c0c17 100644 --- a/arch/riscv/kernel/paravirt.c +++ b/arch/riscv/kernel/paravirt.c @@ -165,8 +165,21 @@ DEFINE_STATIC_CALL(pv_queued_spin_unlock, native_queued_spin_unlock); EXPORT_SYMBOL(__SCK__pv_queued_spin_lock_slowpath); EXPORT_SYMBOL(__SCK__pv_queued_spin_unlock); +static bool nopvspin; +static __init int parse_nopvspin(char *arg) +{ + nopvspin = true; + return 0; +} +early_param("nopvspin", parse_nopvspin); + void __init pv_qspinlock_init(void) { + if (nopvspin) { + pr_info("PV qspinlocks disabled\n"); + return; + } + if (num_possible_cpus() == 1) return;