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 C4CC3C636CC for ; Sat, 4 Feb 2023 22:32:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232500AbjBDWcZ (ORCPT ); Sat, 4 Feb 2023 17:32:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51462 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231386AbjBDWcX (ORCPT ); Sat, 4 Feb 2023 17:32:23 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2770E23112; Sat, 4 Feb 2023 14:32:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:Content-Type: MIME-Version:Message-ID:References:In-Reply-To:Subject:CC:To:From:Date:Sender :Reply-To:Content-ID:Content-Description; bh=KQh88XbsUhz1qg8j553C7PJkpbk+sVrvN6vVjGTZA4o=; b=aK5SHrmjBbZoZkEGl/6tMN4pjL 0Mdho5yapH9Xe/6SSEJRzB5eyL73XPi0wk6jlCEgn5YF7LUGw7Kp72jMtXDg1lglypxAnBUNx3F5O zJg1Amz0EwtP+9eEgLlsaq0gAyGYS9Ahb7q3osKs0AebuIeQH7trEFvyf5OyE+j0tKSALzR7DTv1P J1XwjRYJkejwF+bGpKqjUU1piFNeg4BdmqXoxgB9FVqTk/fILsHI+H2w38cxmUWkWERs+iaUHR6Bn GM46pPoxDGZurcslluuUeCke+UuIaowsL4ETuThXSroDBH1Vd6oErJj9eOp3dS+BNDoXP+B8KMQ9N 0ZfND57w==; Received: from [84.64.40.55] (helo=[127.0.0.1]) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1pOR4H-00FTLV-9M; Sat, 04 Feb 2023 22:31:34 +0000 Date: Sat, 04 Feb 2023 22:31:31 +0000 From: David Woodhouse To: Arjan van de Ven , Kim Phillips , Usama Arif , tglx@linutronix.de CC: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com, paulmck@kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de, hewenliang4@huawei.com, thomas.lendacky@amd.com, seanjc@google.com, pmenzel@molgen.mpg.de, fam.zheng@bytedance.com, punit.agrawal@bytedance.com, simon.evans@bytedance.com, liangma@liangbit.com, Mario Limonciello Subject: Re: [PATCH v6 07/11] x86/smpboot: Disable parallel boot for AMD CPUs User-Agent: K-9 Mail for Android In-Reply-To: <5ba476f3-e0ac-d630-ce1d-18ab9885496f@linux.intel.com> References: <20230202215625.3248306-1-usama.arif@bytedance.com> <20230202215625.3248306-8-usama.arif@bytedance.com> <5ba476f3-e0ac-d630-ce1d-18ab9885496f@linux.intel.com> Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4 February 2023 18:18:55 GMT, Arjan van de Ven wrote: >>=20 >> However=2E=2E=2E >>=20 >> Even though we *can* support non-X2APIC processors, we *might* want to >> play it safe and not go back that far; only enabling parallel bringup >> on machines with X2APIC which roughly correlates with "lots of CPUs" >> since that's where the benefit is=2E > >I think that this is the right approach, at least on the initial patch se= ries=2E >KISS principle; do all the easy-but-important cases first, get it stable = and working >and in later series/kernels the range can be expanded=2E=2E=2E=2E if it m= atters=2E Agreed=2E I'll split it to do it only with X2APIC for the initial series, = and then hold the CPUID 0x1 part back for the next phase=2E