From patchwork Fri Sep 13 07:59:06 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Roger Pau Monne X-Patchwork-Id: 13803076 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9522CFA3729 for ; Fri, 13 Sep 2024 07:59:39 +0000 (UTC) Received: from list by lists.xenproject.org with outflank-mailman.798036.1208180 (Exim 4.92) (envelope-from ) id 1sp1D9-00049K-Vt; Fri, 13 Sep 2024 07:59:23 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 798036.1208180; Fri, 13 Sep 2024 07:59:23 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sp1D9-00049D-TC; Fri, 13 Sep 2024 07:59:23 +0000 Received: by outflank-mailman (input) for mailman id 798036; Fri, 13 Sep 2024 07:59:22 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1sp1D8-0003uX-El for xen-devel@lists.xenproject.org; Fri, 13 Sep 2024 07:59:22 +0000 Received: from mail-wm1-x32c.google.com (mail-wm1-x32c.google.com [2a00:1450:4864:20::32c]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id 14cf82b4-71a6-11ef-99a2-01e77a169b0f; Fri, 13 Sep 2024 09:59:20 +0200 (CEST) Received: by mail-wm1-x32c.google.com with SMTP id 5b1f17b1804b1-428e1915e18so5173605e9.1 for ; Fri, 13 Sep 2024 00:59:20 -0700 (PDT) Received: from localhost ([213.195.124.163]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-42d9b16bfbfsm14947075e9.22.2024.09.13.00.59.18 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Sep 2024 00:59:18 -0700 (PDT) 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: 14cf82b4-71a6-11ef-99a2-01e77a169b0f DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1726214359; x=1726819159; darn=lists.xenproject.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=KJgIdTeGxaw7ZlxEbyNjVU/dqlACBdHjFk91wT/lMP4=; b=JGX1pSa8gL8GUiIZ8Ugl45/s/B4RRXBvdzBCbCi2/w4I7cI90UZIKknUICO019NTom 1tGZknKnek+7q2ltvvo4WweiMKFKPmYqCVKwlM8jhWLUwgvWkfSa3hcSCIx3V3QP9lZE I3epSXbeToFFHFDLUcbF6oagyMewZ3ObPN8eA= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1726214359; x=1726819159; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=KJgIdTeGxaw7ZlxEbyNjVU/dqlACBdHjFk91wT/lMP4=; b=J6F2BGdkORd0MiE02oMZWC0quwGek4Pz6ZPaSk/lzh9wZLq5SnEom5XSEGETcGiLRk E2jFCFmzUght/khkA+jsbuq8sKVlAacVTYf+fp9Hw6fDQhvMlZP9LbqVtxir8YuPz2de wAl3PboCc4ZFLyyx+jM3vvHU1cgY2442GwpRn8uxdEnsDbU9IOT/19WwvfheGz+auSUw a8/vVEXGRWgkioHM24EBnlEiviIvxiWijwjMGsCAck0XsiulYXA1rXSXqjSKpYbB+YrS AyG/WFaqGp+f1q2ELREUOxtLvLUit/cxSfX934tBHM424fCr3gzcm1nilHb1ZlVZJqV+ 0vZQ== X-Gm-Message-State: AOJu0YwCkiiYYOss0uXP3yNwMt7171ABAnkkqjq6OaVIq8dQWo1j6Fq1 2xxSnOGjkGiT3VXjIJL94u0p8PYq8kB+88vQWc+5rjdHr3FmnaPCmFTjkK0Knr+G8WE90BETtbP A X-Google-Smtp-Source: AGHT+IEpyjfoR6VNGeeMIaigttSgEqTbHzHjL+L/dZTtd9QUnTteQrtHRhilct47Kt1FsJW1CDYTqw== X-Received: by 2002:a05:600c:4f51:b0:42c:b6db:4270 with SMTP id 5b1f17b1804b1-42d90722068mr11157785e9.11.1726214358750; Fri, 13 Sep 2024 00:59:18 -0700 (PDT) From: Roger Pau Monne To: xen-devel@lists.xenproject.org Cc: "Daniel P. Smith" , =?utf-8?q?Marek_Marczy?= =?utf-8?q?kowski-G=C3=B3recki?= , Roger Pau Monne , Andrew Cooper , Jan Beulich , Julien Grall , Stefano Stabellini Subject: [PATCH v7 1/2] x86/time: introduce command line option to select wallclock Date: Fri, 13 Sep 2024 09:59:06 +0200 Message-ID: <20240913075907.34460-2-roger.pau@citrix.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240913075907.34460-1-roger.pau@citrix.com> References: <20240913075907.34460-1-roger.pau@citrix.com> MIME-Version: 1.0 Allow setting the used wallclock from the command line. When the option is set to a value different than `auto` the probing is bypassed and the selected implementation is used (as long as it's available). The `xen` and `efi` options require being booted as a Xen guest (with Xen guest supported built-in) or from UEFI firmware respectively. Signed-off-by: Roger Pau Monné --- Changes since v6: - Clarify documentation regarding repeated using of the wallclock command line option. Changes since v5: - Do EFI run-time services checking after command line parsing. Changes since v3: - Note xen option is only available if Xen guest support it built. - Fix typo. --- docs/misc/xen-command-line.pandoc | 21 ++++++++++++++++ xen/arch/x86/time.c | 41 ++++++++++++++++++++++++++++++- 2 files changed, 61 insertions(+), 1 deletion(-) diff --git a/docs/misc/xen-command-line.pandoc b/docs/misc/xen-command-line.pandoc index 959cf45b55d9..2a9b3b9b8975 100644 --- a/docs/misc/xen-command-line.pandoc +++ b/docs/misc/xen-command-line.pandoc @@ -2816,6 +2816,27 @@ vwfi to `native` reduces irq latency significantly. It can also lead to suboptimal scheduling decisions, but only when the system is oversubscribed (i.e., in total there are more vCPUs than pCPUs). +### wallclock (x86) +> `= auto | xen | cmos | efi` + +> Default: `auto` + +Allow forcing the usage of a specific wallclock source. + + * `auto` let the hypervisor select the clocksource based on internal + heuristics. + + * `xen` force usage of the Xen shared_info wallclock when booted as a Xen + guest. This option is only available if the hypervisor was compiled with + `CONFIG_XEN_GUEST` enabled. + + * `cmos` force usage of the CMOS RTC wallclock. + + * `efi` force usage of the EFI_GET_TIME run-time method when booted from EFI + firmware. + +If the selected option is invalid or not available Xen will default to `auto`. + ### watchdog (x86) > `= force | ` diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c index 29b026735e5d..e4751684951e 100644 --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -1552,6 +1552,37 @@ static const char *__init wallclock_type_to_string(void) return ""; } +static int __init cf_check parse_wallclock(const char *arg) +{ + wallclock_source = WALLCLOCK_UNSET; + + if ( !arg ) + return -EINVAL; + + if ( !strcmp("auto", arg) ) + ASSERT(wallclock_source == WALLCLOCK_UNSET); + else if ( !strcmp("xen", arg) ) + { + if ( !xen_guest ) + return -EINVAL; + + wallclock_source = WALLCLOCK_XEN; + } + else if ( !strcmp("cmos", arg) ) + wallclock_source = WALLCLOCK_CMOS; + else if ( !strcmp("efi", arg) ) + /* + * Checking if run-time services are available must be done after + * command line parsing. + */ + wallclock_source = WALLCLOCK_EFI; + else + return -EINVAL; + + return 0; +} +custom_param("wallclock", parse_wallclock); + static void __init probe_wallclock(void) { ASSERT(wallclock_source == WALLCLOCK_UNSET); @@ -2527,7 +2558,15 @@ int __init init_xen_time(void) open_softirq(TIME_CALIBRATE_SOFTIRQ, local_time_calibration); - probe_wallclock(); + /* + * EFI run time services can be disabled from the command line, hence the + * check for them cannot be done as part of the wallclock option parsing. + */ + if ( wallclock_source == WALLCLOCK_EFI && !efi_enabled(EFI_RS) ) + wallclock_source = WALLCLOCK_UNSET; + + if ( wallclock_source == WALLCLOCK_UNSET ) + probe_wallclock(); printk(XENLOG_INFO "Wallclock source: %s\n", wallclock_type_to_string()); From patchwork Fri Sep 13 07:59:07 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Roger Pau Monne X-Patchwork-Id: 13803075 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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 9A149FA3728 for ; 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Fri, 13 Sep 2024 00:59:20 -0700 (PDT) From: Roger Pau Monne To: xen-devel@lists.xenproject.org Cc: "Daniel P. Smith" , =?utf-8?q?Marek_Marczy?= =?utf-8?q?kowski-G=C3=B3recki?= , Roger Pau Monne , Jan Beulich , Andrew Cooper Subject: [PATCH v7 2/2] x86/time: prefer CMOS over EFI_GET_TIME Date: Fri, 13 Sep 2024 09:59:07 +0200 Message-ID: <20240913075907.34460-3-roger.pau@citrix.com> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240913075907.34460-1-roger.pau@citrix.com> References: <20240913075907.34460-1-roger.pau@citrix.com> MIME-Version: 1.0 The EFI_GET_TIME implementation is well known to be broken for many firmware implementations, for Xen the result on such implementations are: ----[ Xen-4.19-unstable x86_64 debug=y Tainted: C ]---- CPU: 0 RIP: e008:[<0000000062ccfa70>] 0000000062ccfa70 [...] Xen call trace: [<0000000062ccfa70>] R 0000000062ccfa70 [<00000000732e9a3f>] S 00000000732e9a3f [] F arch/x86/time.c#get_cmos_time+0x1b3/0x26e [] F init_xen_time+0x28/0xa4 [] F __start_xen+0x1ee7/0x2578 [] F __high_start+0x94/0xa0 Pagetable walk from 0000000062ccfa70: L4[0x000] = 000000207ef1c063 ffffffffffffffff L3[0x001] = 000000005d6c0063 ffffffffffffffff L2[0x116] = 8000000062c001e3 ffffffffffffffff (PSE) **************************************** Panic on CPU 0: FATAL PAGE FAULT [error_code=0011] Faulting linear address: 0000000062ccfa70 **************************************** Swap the preference to default to CMOS first, and EFI later, in an attempt to use EFI_GET_TIME as a last resort option only. Note that Linux for example doesn't allow calling the get_time method, and instead provides a dummy handler that unconditionally returns EFI_UNSUPPORTED on x86-64. Such change in the preferences requires some re-arranging of the function logic, so that panic messages with workaround suggestions are suitably printed. Signed-off-by: Roger Pau Monné Acked-by: Andrew Cooper Acked-by: Marek Marczykowski-Górecki --- Changes since v2: - Updated to match previous changes. --- xen/arch/x86/time.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/xen/arch/x86/time.c b/xen/arch/x86/time.c index e4751684951e..b86e4d58b40c 100644 --- a/xen/arch/x86/time.c +++ b/xen/arch/x86/time.c @@ -1592,14 +1592,14 @@ static void __init probe_wallclock(void) wallclock_source = WALLCLOCK_XEN; return; } - if ( efi_enabled(EFI_RS) && efi_get_time() ) + if ( cmos_rtc_probe() ) { - wallclock_source = WALLCLOCK_EFI; + wallclock_source = WALLCLOCK_CMOS; return; } - if ( cmos_rtc_probe() ) + if ( efi_enabled(EFI_RS) && efi_get_time() ) { - wallclock_source = WALLCLOCK_CMOS; + wallclock_source = WALLCLOCK_EFI; return; }