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 X-Spam-Level: X-Spam-Status: No, score=-24.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D2C81C4743C for ; Mon, 21 Jun 2021 16:33:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B59BD613E0 for ; Mon, 21 Jun 2021 16:33:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231768AbhFUQf0 (ORCPT ); Mon, 21 Jun 2021 12:35:26 -0400 Received: from mail.kernel.org ([198.145.29.99]:49598 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232347AbhFUQbN (ORCPT ); Mon, 21 Jun 2021 12:31:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id F1FF9613FD; Mon, 21 Jun 2021 16:25:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1624292735; bh=SQe5bDNh0L5c6vBR6ZwA5SFiHPDkCckVDZfp68aHllo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GskSs3PbL0IrcJKQzvqPCc7cgjvQEZR0ADa0lQkv3EP63HRTm9Pw0dU1PC+Ohzmaq 1LKV6qDuc/HcCDlxdtbzjeZZQ4xnV/ppKv5exFG/937Hh95gb30iVnG6MP7iOarvU9 t67ZHZqqSxi3qmdJQgH0iVLbK4weVa1rAf01E+AM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, =?UTF-8?q?Pali=20Roh=C3=A1r?= , Lorenzo Pieralisi , Bjorn Helgaas , =?UTF-8?q?Marek=20Beh=C3=BAn?= Subject: [PATCH 5.10 109/146] PCI: aardvark: Fix kernel panic during PIO transfer Date: Mon, 21 Jun 2021 18:15:39 +0200 Message-Id: <20210621154918.246240162@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210621154911.244649123@linuxfoundation.org> References: <20210621154911.244649123@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: linux-kernel@vger.kernel.org From: Pali Rohár commit f18139966d072dab8e4398c95ce955a9742e04f7 upstream. Trying to start a new PIO transfer by writing value 0 in PIO_START register when previous transfer has not yet completed (which is indicated by value 1 in PIO_START) causes an External Abort on CPU, which results in kernel panic: SError Interrupt on CPU0, code 0xbf000002 -- SError Kernel panic - not syncing: Asynchronous SError Interrupt To prevent kernel panic, it is required to reject a new PIO transfer when previous one has not finished yet. If previous PIO transfer is not finished yet, the kernel may issue a new PIO request only if the previous PIO transfer timed out. In the past the root cause of this issue was incorrectly identified (as it often happens during link retraining or after link down event) and special hack was implemented in Trusted Firmware to catch all SError events in EL3, to ignore errors with code 0xbf000002 and not forwarding any other errors to kernel and instead throw panic from EL3 Trusted Firmware handler. Links to discussion and patches about this issue: https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50 https://lore.kernel.org/linux-pci/20190316161243.29517-1-repk@triplefau.lt/ https://lore.kernel.org/linux-pci/971be151d24312cc533989a64bd454b4@www.loen.fr/ https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/1541 But the real cause was the fact that during link retraining or after link down event the PIO transfer may take longer time, up to the 1.44s until it times out. This increased probability that a new PIO transfer would be issued by kernel while previous one has not finished yet. After applying this change into the kernel, it is possible to revert the mentioned TF-A hack and SError events do not have to be caught in TF-A EL3. Link: https://lore.kernel.org/r/20210608203655.31228-1-pali@kernel.org Signed-off-by: Pali Rohár Signed-off-by: Lorenzo Pieralisi Signed-off-by: Bjorn Helgaas Reviewed-by: Marek Behún Cc: stable@vger.kernel.org # 7fbcb5da811b ("PCI: aardvark: Don't rely on jiffies while holding spinlock") Signed-off-by: Greg Kroah-Hartman --- drivers/pci/controller/pci-aardvark.c | 49 +++++++++++++++++++++++++++------- 1 file changed, 40 insertions(+), 9 deletions(-) --- a/drivers/pci/controller/pci-aardvark.c +++ b/drivers/pci/controller/pci-aardvark.c @@ -514,7 +514,7 @@ static int advk_pcie_wait_pio(struct adv udelay(PIO_RETRY_DELAY); } - dev_err(dev, "config read/write timed out\n"); + dev_err(dev, "PIO read/write transfer time out\n"); return -ETIMEDOUT; } @@ -657,6 +657,35 @@ static bool advk_pcie_valid_device(struc return true; } +static bool advk_pcie_pio_is_running(struct advk_pcie *pcie) +{ + struct device *dev = &pcie->pdev->dev; + + /* + * Trying to start a new PIO transfer when previous has not completed + * cause External Abort on CPU which results in kernel panic: + * + * SError Interrupt on CPU0, code 0xbf000002 -- SError + * Kernel panic - not syncing: Asynchronous SError Interrupt + * + * Functions advk_pcie_rd_conf() and advk_pcie_wr_conf() are protected + * by raw_spin_lock_irqsave() at pci_lock_config() level to prevent + * concurrent calls at the same time. But because PIO transfer may take + * about 1.5s when link is down or card is disconnected, it means that + * advk_pcie_wait_pio() does not always have to wait for completion. + * + * Some versions of ARM Trusted Firmware handles this External Abort at + * EL3 level and mask it to prevent kernel panic. Relevant TF-A commit: + * https://git.trustedfirmware.org/TF-A/trusted-firmware-a.git/commit/?id=3c7dcdac5c50 + */ + if (advk_readl(pcie, PIO_START)) { + dev_err(dev, "Previous PIO read/write transfer is still running\n"); + return true; + } + + return false; +} + static int advk_pcie_rd_conf(struct pci_bus *bus, u32 devfn, int where, int size, u32 *val) { @@ -673,9 +702,10 @@ static int advk_pcie_rd_conf(struct pci_ return pci_bridge_emul_conf_read(&pcie->bridge, where, size, val); - /* Start PIO */ - advk_writel(pcie, 0, PIO_START); - advk_writel(pcie, 1, PIO_ISR); + if (advk_pcie_pio_is_running(pcie)) { + *val = 0xffffffff; + return PCIBIOS_SET_FAILED; + } /* Program the control register */ reg = advk_readl(pcie, PIO_CTRL); @@ -694,7 +724,8 @@ static int advk_pcie_rd_conf(struct pci_ /* Program the data strobe */ advk_writel(pcie, 0xf, PIO_WR_DATA_STRB); - /* Start the transfer */ + /* Clear PIO DONE ISR and start the transfer */ + advk_writel(pcie, 1, PIO_ISR); advk_writel(pcie, 1, PIO_START); ret = advk_pcie_wait_pio(pcie); @@ -734,9 +765,8 @@ static int advk_pcie_wr_conf(struct pci_ if (where % size) return PCIBIOS_SET_FAILED; - /* Start PIO */ - advk_writel(pcie, 0, PIO_START); - advk_writel(pcie, 1, PIO_ISR); + if (advk_pcie_pio_is_running(pcie)) + return PCIBIOS_SET_FAILED; /* Program the control register */ reg = advk_readl(pcie, PIO_CTRL); @@ -763,7 +793,8 @@ static int advk_pcie_wr_conf(struct pci_ /* Program the data strobe */ advk_writel(pcie, data_strobe, PIO_WR_DATA_STRB); - /* Start the transfer */ + /* Clear PIO DONE ISR and start the transfer */ + advk_writel(pcie, 1, PIO_ISR); advk_writel(pcie, 1, PIO_START); ret = advk_pcie_wait_pio(pcie);