From patchwork Mon Feb 1 12:42:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12058949 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=-17.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 C8999C433E0 for ; Mon, 1 Feb 2021 12:42:48 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 628CA64E9B for ; Mon, 1 Feb 2021 12:42:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 628CA64E9B Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.79837.145459 (Exim 4.92) (envelope-from ) id 1l6YXP-0003Gv-Ar; Mon, 01 Feb 2021 12:42:39 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 79837.145459; Mon, 01 Feb 2021 12:42:39 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l6YXP-0003Go-6R; Mon, 01 Feb 2021 12:42:39 +0000 Received: by outflank-mailman (input) for mailman id 79837; Mon, 01 Feb 2021 12:42:37 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1l6YXN-0003Gh-TX for xen-devel@lists.xenproject.org; Mon, 01 Feb 2021 12:42:37 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 067a2b04-0906-4776-b2c3-2a24514f1815; Mon, 01 Feb 2021 12:42:36 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id EE3A3ABD5; Mon, 1 Feb 2021 12:42:35 +0000 (UTC) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 067a2b04-0906-4776-b2c3-2a24514f1815 X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1612183356; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=pQE/B5fzZf3jiK+QiCdMMnScKlarCr8sADBb9isYXQM=; b=ogx0M9L/sRFh0TkJYhEmDi/1u4/+aqxSxUPQRicSox3pAZqKQ0ZpEjUfMfKltleZlOEtmK kJkKGzh1oJf9PMnYfddaFWWHl6i8PqtR2+VMg4oH9LiKtBMj0ob/cUvScvzz/zJM3+B9if cPpH/XqQwjcIJhJyXxLX8PLnbWr1puM= Subject: [PATCH v2 1/3] x86/time: change initiation of the calibration timer From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?utf-8?q?Roger_Pau_Monn=C3=A9?= , Claudemir Todo Bom References: Message-ID: Date: Mon, 1 Feb 2021 13:42:35 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US Setting the timer a second (EPOCH) into the future at a random point during boot (prior to bringing up APs and prior to launching Dom0) does not yield predictable results: The timer may expire while we're still bringing up APs (too early) or when Dom0 already boots (too late). Instead invoke the timer handler function explicitly at a predictable point in time, once we've established the rendezvous function to use (and hence also once all APs are online). This will, through the raising and handling of TIMER_SOFTIRQ, then also have the effect of arming the timer. Signed-off-by: Jan Beulich Acked-by: Roger Pau Monné --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -854,9 +854,7 @@ static void resume_platform_timer(void) static void __init reset_platform_timer(void) { - /* Deactivate any timers running */ kill_timer(&plt_overflow_timer); - kill_timer(&calibration_timer); /* Reset counters and stamps */ spin_lock_irq(&platform_timer_lock); @@ -1956,19 +1954,13 @@ static void __init reset_percpu_time(voi t->stamp.master_stime = t->stamp.local_stime; } -static void __init try_platform_timer_tail(bool late) +static void __init try_platform_timer_tail(void) { init_timer(&plt_overflow_timer, plt_overflow, NULL, 0); plt_overflow(NULL); platform_timer_stamp = plt_stamp64; stime_platform_stamp = NOW(); - - if ( !late ) - init_percpu_time(); - - init_timer(&calibration_timer, time_calibration, NULL, 0); - set_timer(&calibration_timer, NOW() + EPOCH); } /* Late init function, after all cpus have booted */ @@ -2009,10 +2001,13 @@ static int __init verify_tsc_reliability time_calibration_rendezvous_fn = time_calibration_nop_rendezvous; /* Finish platform timer switch. */ - try_platform_timer_tail(true); + try_platform_timer_tail(); printk("Switched to Platform timer %s TSC\n", freq_string(plt_src.frequency)); + + time_calibration(NULL); + return 0; } } @@ -2033,6 +2028,8 @@ static int __init verify_tsc_reliability !boot_cpu_has(X86_FEATURE_TSC_RELIABLE) ) time_calibration_rendezvous_fn = time_calibration_tsc_rendezvous; + time_calibration(NULL); + return 0; } __initcall(verify_tsc_reliability); @@ -2048,7 +2045,11 @@ int __init init_xen_time(void) do_settime(get_wallclock_time(), 0, NOW()); /* Finish platform timer initialization. */ - try_platform_timer_tail(false); + try_platform_timer_tail(); + + init_percpu_time(); + + init_timer(&calibration_timer, time_calibration, NULL, 0); /* * Setup space to track per-socket TSC_ADJUST values. Don't fiddle with