From patchwork Mon Sep 19 14:40:57 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: 607611 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 1CBA9ECAAD3 for ; Mon, 19 Sep 2022 14:41:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229787AbiISOlU (ORCPT ); Mon, 19 Sep 2022 10:41:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44218 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229521AbiISOlM (ORCPT ); Mon, 19 Sep 2022 10:41:12 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3E036114E; Mon, 19 Sep 2022 07:41:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1663598471; x=1695134471; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=38Iy38ftkISKzc0y4uuVPmb65R/Pe1Mz6gRWMcovat4=; b=npJI+jHFk4Zm3TXFSmR12BGiAdH2/OUij+qJqX7Rw+bVSKw6ZkRlQqmM LsMQm/9Mvl92VgqfuAw8yjtoQ5TzO2aN3wX2/g/QsU5+aKpdwQPtfZ6jN CxA+uAQ0ifZlEufdVrA54eI5jGIX7Fg0Ee7aZaDo7kZBweSbd2TAXkKBG Hn6dULg6qmLdaYCeGneL7k8sLIH5ew9PHrD7Hdef15OWQWXwX8MrYcMYR ftQoifEtFGwpzGY80dTLRgNNjEK7ELmhUM3hfW6Q+Rqc/vYtsVH27ncyz d8EVrgdYV1kjE96Ub9VcmR3sMFvRUhzVLksIGS1P0uONzVmsuCTUdBEkE A==; X-IronPort-AV: E=McAfee;i="6500,9779,10475"; a="299407522" X-IronPort-AV: E=Sophos;i="5.93,328,1654585200"; d="scan'208";a="299407522" Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2022 07:41:11 -0700 X-IronPort-AV: E=Sophos;i="5.93,328,1654585200"; d="scan'208";a="863583868" Received: from iswiersz-mobl1.ger.corp.intel.com (HELO ijarvine-MOBL2.ger.corp.intel.com) ([10.252.33.172]) by fmsmga006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 Sep 2022 07:41:07 -0700 From: =?utf-8?q?Ilpo_J=C3=A4rvinen?= To: Lennert Buytenhek , Andy Shevchenko , Greg Kroah-Hartman , Jiri Slaby , Alex Williamson , Aristeu Sergio Rozanski Filho , Andrew Morton , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Cc: =?utf-8?q?Ilpo_J=C3=A4rvinen?= , Lennert Buytenhek Subject: [PATCH v3 1/1] serial: 8250: Toggle IER bits on only after irq has been set up Date: Mon, 19 Sep 2022 17:40:57 +0300 Message-Id: <20220919144057.12241-1-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 on Ice Lake-D 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 If the IRQ hasn't been set up yet, the UART will have zeroes in its MSI address/data registers. Disabling the IRQ at the interrupt controller won't stop the UART from performing a DMA write to the address programmed in its MSI address register (zero) when it wants to signal an interrupt. The UARTs (in Ice Lake-D) implement PCI 2.1 style MSI without masking capability, so there is no way to mask the interrupt at the source PCI function level, except disabling the MSI capability entirely, but that would cause it to fall back to INTx# assertion, and the PCI specification prohibits disabling the MSI capability as a way to mask a function's interrupt service request. The MSI address register is zeroed during by the hangup as the irq is freed. The interrupt is signalled during serial8250_do_startup() performing a 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") Reviewed-by: Andy Shevchenko Signed-off-by: Ilpo Järvinen --- v3: - Improved the commit with Lennert's superior descriptions. - Added Andy's Rev-by 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