From mboxrd@z Thu Jan 1 00:00:00 1970 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 541F6C4332F for ; Mon, 24 Jan 2022 21:46:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1573568AbiAXVpP (ORCPT ); Mon, 24 Jan 2022 16:45:15 -0500 Received: from ams.source.kernel.org ([145.40.68.75]:50300 "EHLO ams.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1456325AbiAXVio (ORCPT ); Mon, 24 Jan 2022 16:38:44 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id DF872B81233; Mon, 24 Jan 2022 21:38:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 19BB0C340E4; Mon, 24 Jan 2022 21:38:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643060315; bh=4KnP9f2BG2N0gQWpClCCaBlbp1tyU3Pjw2Z1LPrgmQ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cenakRCK9CnTOdZM4c2d6HdhVsNEiRteH3JRptVZhoBSyjlcYg5qKT4ZItgxIWzEO UbIHWjpr+Fm4/kYGYF39w89YLLunWLolbGoSGJ4DCmhGh0m/9bAsTIt5hQzlcyDjbH qhdNW8plCebWFm30/Fa64BW7a2w7CyPsQFw00MTw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joseph Bao , Lukas Wunner , Bjorn Helgaas , Stuart Hayes Subject: [PATCH 5.16 0874/1039] PCI: pciehp: Fix infinite loop in IRQ handler upon power fault Date: Mon, 24 Jan 2022 19:44:23 +0100 Message-Id: <20220124184154.674800632@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184125.121143506@linuxfoundation.org> References: <20220124184125.121143506@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Lukas Wunner commit 23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12 upstream. The Power Fault Detected bit in the Slot Status register differs from all other hotplug events in that it is sticky: It can only be cleared after turning off slot power. Per PCIe r5.0, sec. 6.7.1.8: If a power controller detects a main power fault on the hot-plug slot, it must automatically set its internal main power fault latch [...]. The main power fault latch is cleared when software turns off power to the hot-plug slot. The stickiness used to cause interrupt storms and infinite loops which were fixed in 2009 by commits 5651c48cfafe ("PCI pciehp: fix power fault interrupt storm problem") and 99f0169c17f3 ("PCI: pciehp: enable software notification on empty slots"). Unfortunately in 2020 the infinite loop issue was inadvertently reintroduced by commit 8edf5332c393 ("PCI: pciehp: Fix MSI interrupt race"): The hardirq handler pciehp_isr() clears the PFD bit until pciehp's power_fault_detected flag is set. That happens in the IRQ thread pciehp_ist(), which never learns of the event because the hardirq handler is stuck in an infinite loop. Fix by setting the power_fault_detected flag already in the hardirq handler. Link: https://bugzilla.kernel.org/show_bug.cgi?id=214989 Link: https://lore.kernel.org/linux-pci/DM8PR11MB5702255A6A92F735D90A4446868B9@DM8PR11MB5702.namprd11.prod.outlook.com Fixes: 8edf5332c393 ("PCI: pciehp: Fix MSI interrupt race") Link: https://lore.kernel.org/r/66eaeef31d4997ceea357ad93259f290ededecfd.1637187226.git.lukas@wunner.de Reported-by: Joseph Bao Tested-by: Joseph Bao Signed-off-by: Lukas Wunner Signed-off-by: Bjorn Helgaas Cc: stable@vger.kernel.org # v4.19+ Cc: Stuart Hayes Signed-off-by: Greg Kroah-Hartman --- drivers/pci/hotplug/pciehp_hpc.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/drivers/pci/hotplug/pciehp_hpc.c +++ b/drivers/pci/hotplug/pciehp_hpc.c @@ -642,6 +642,8 @@ read_status: */ if (ctrl->power_fault_detected) status &= ~PCI_EXP_SLTSTA_PFD; + else if (status & PCI_EXP_SLTSTA_PFD) + ctrl->power_fault_detected = true; events |= status; if (!events) { @@ -651,7 +653,7 @@ read_status: } if (status) { - pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, events); + pcie_capability_write_word(pdev, PCI_EXP_SLTSTA, status); /* * In MSI mode, all event bits must be zero before the port @@ -725,8 +727,7 @@ static irqreturn_t pciehp_ist(int irq, v } /* Check Power Fault Detected */ - if ((events & PCI_EXP_SLTSTA_PFD) && !ctrl->power_fault_detected) { - ctrl->power_fault_detected = 1; + if (events & PCI_EXP_SLTSTA_PFD) { ctrl_err(ctrl, "Slot(%s): Power fault\n", slot_name(ctrl)); pciehp_set_indicators(ctrl, PCI_EXP_SLTCTL_PWR_IND_OFF, PCI_EXP_SLTCTL_ATTN_IND_ON);