From patchwork Fri Sep 16 13:38:04 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: =?utf-8?q?Ilpo_J=C3=A4rvinen?= X-Patchwork-Id: 606941 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 C9B03ECAAD8 for ; Fri, 16 Sep 2022 13:38:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229872AbiIPNiS (ORCPT ); Fri, 16 Sep 2022 09:38:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48952 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229581AbiIPNiS (ORCPT ); Fri, 16 Sep 2022 09:38:18 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4CD88AC267; Fri, 16 Sep 2022 06:38:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663335497; x=1694871497; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=sJMe/1PYpsqbrFNWnFUVcRts/I3YQPfG92WoPV3Im7Y=; b=TnpMdf4NKf81gyfdZAu+w/QHA1bNnaT04CWmaCxYYXn2vIKvRZoHPVtC N0YXdnL/3ud1Fm6UtHlMsJeiPMIF9zou98WMT5ip3kOqMR7o6skF5IC8X VM/6AwIRA/z9SFjtg7DBLjSqD/NEfYoHDgiDgJ7KPB9CfEXWJsOCoacNH i3jXKl7Qfl4nexOJpWH5ZJcrIsV6Ns/IzIr1GufXMwOQultBVwusRp0Xo E8X7OQEO8kfGxCf8PVrQOgUMZKWZJt9mOGJaGJkPkBxSc0uUWF28mhP9c 3s35Qwg0r6CfoHFUN5M0c2NkNnWTLhmQAFLkUxeOCCBMDyBEg1L8U6msF Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10472"; a="325265318" X-IronPort-AV: E=Sophos;i="5.93,320,1654585200"; d="scan'208";a="325265318" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2022 06:38:17 -0700 X-IronPort-AV: E=Sophos;i="5.93,320,1654585200"; d="scan'208";a="946375217" Received: from lroque-mobl1.amr.corp.intel.com (HELO ijarvine-MOBL2.ger.corp.intel.com) ([10.251.209.126]) by fmsmga005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Sep 2022 06:38:14 -0700 From: =?utf-8?q?Ilpo_J=C3=A4rvinen?= To: Lennert Buytenhek , Andy Shevchenko , Greg Kroah-Hartman , Jiri Slaby , Aristeu Sergio Rozanski Filho , Alex Williamson , Andrew Morton , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?utf-8?q?Ilpo_J=C3=A4rvinen?= , Lennert Buytenhek Subject: [PATCH v2 1/1] serial: 8250: Turn IER bits on only after irq has been set up Date: Fri, 16 Sep 2022 16:38:04 +0300 Message-Id: <20220916133804.15196-1-ilpo.jarvinen@linux.intel.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org Invoking TIOCVHANGUP on 8250_mid port and then reopening the port triggers these faults during serial8250_do_startup(): DMAR: DRHD: handling fault status reg 3 DMAR: [DMA Write NO_PASID] Request device [00:1a.0] fault addr 0x0 [fault reason 0x05] PTE Write access is not set The cause is a DMA write to the address in MSI address register that was zeroed during the hangup as the irq was freed. The writes are triggered due signalling an interrupt during the THRE test that temporarily toggles THRI in IER. The THRE test currently occurs before UART's irq (and MSI address) is properly set up. Refactor serial8250_do_startup() such that irq is set up before the THRE test. The current irq setup code is intermixed with the timer setup code. As THRE test must be performed prior to the timer setup, extract it into own function and call it only after the THRE test. Reported-by: Lennert Buytenhek Tested-by: Lennert Buytenhek Fixes: 40b36daad0ac ("[PATCH] 8250 UART backup timer") Signed-off-by: Ilpo Järvinen --- v2: - Remove unnecessary changes to comments & newlines - Change Lennert's email & add Tested-by - Improve description of the problem (thank to Lennert's explanation) drivers/tty/serial/8250/8250.h | 2 ++ drivers/tty/serial/8250/8250_core.c | 16 +++++++++++----- drivers/tty/serial/8250/8250_port.c | 8 +++++--- 3 files changed, 18 insertions(+), 8 deletions(-) diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h index 287153d32536..dbf4c1204bf3 100644 --- a/drivers/tty/serial/8250/8250.h +++ b/drivers/tty/serial/8250/8250.h @@ -403,3 +403,5 @@ static inline int serial_index(struct uart_port *port) { return port->minor - 64; } + +void univ8250_setup_timer(struct uart_8250_port *up); diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c index 2e83e7367441..10d535640434 100644 --- a/drivers/tty/serial/8250/8250_core.c +++ b/drivers/tty/serial/8250/8250_core.c @@ -298,10 +298,9 @@ static void serial8250_backup_timeout(struct timer_list *t) jiffies + uart_poll_timeout(&up->port) + HZ / 5); } -static int univ8250_setup_irq(struct uart_8250_port *up) +void univ8250_setup_timer(struct uart_8250_port *up) { struct uart_port *port = &up->port; - int retval = 0; /* * The above check will only give an accurate result the first time @@ -322,10 +321,17 @@ static int univ8250_setup_irq(struct uart_8250_port *up) */ if (!port->irq) mod_timer(&up->timer, jiffies + uart_poll_timeout(port)); - else - retval = serial_link_irq_chain(up); +} +EXPORT_SYMBOL_GPL(univ8250_setup_timer); - return retval; +static int univ8250_setup_irq(struct uart_8250_port *up) +{ + struct uart_port *port = &up->port; + + if (port->irq) + return serial_link_irq_chain(up); + + return 0; } static void univ8250_release_irq(struct uart_8250_port *up) diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c index 39b35a61958c..6e8e16227a3a 100644 --- a/drivers/tty/serial/8250/8250_port.c +++ b/drivers/tty/serial/8250/8250_port.c @@ -2294,6 +2294,10 @@ int serial8250_do_startup(struct uart_port *port) if (port->irq && (up->port.flags & UPF_SHARE_IRQ)) up->port.irqflags |= IRQF_SHARED; + retval = up->ops->setup_irq(up); + if (retval) + goto out; + if (port->irq && !(up->port.flags & UPF_NO_THRE_TEST)) { unsigned char iir1; @@ -2336,9 +2340,7 @@ int serial8250_do_startup(struct uart_port *port) } } - retval = up->ops->setup_irq(up); - if (retval) - goto out; + univ8250_setup_timer(up); /* * Now, initialize the UART