From patchwork Wed Mar 20 18:14:07 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Garry X-Patchwork-Id: 1059442 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=linux-pci-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=huawei.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 44PdNf5VNPz9sP3 for ; Thu, 21 Mar 2019 05:14:26 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727166AbfCTSOZ (ORCPT ); Wed, 20 Mar 2019 14:14:25 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:5722 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726611AbfCTSOZ (ORCPT ); Wed, 20 Mar 2019 14:14:25 -0400 Received: from DGGEMS404-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 9F14E2DAE325F106F641; Thu, 21 Mar 2019 02:14:22 +0800 (CST) Received: from localhost.localdomain (10.67.212.75) by DGGEMS404-HUB.china.huawei.com (10.3.19.204) with Microsoft SMTP Server id 14.3.408.0; Thu, 21 Mar 2019 02:14:13 +0800 From: John Garry To: , , , , CC: , , , , , , , "John Garry" Subject: [PATCH v2 0/3] Fix system crash for accessing unmapped IO port regions Date: Thu, 21 Mar 2019 02:14:07 +0800 Message-ID: <1553105650-28012-1-git-send-email-john.garry@huawei.com> X-Mailer: git-send-email 2.8.1 MIME-Version: 1.0 X-Originating-IP: [10.67.212.75] X-CFilter-Loop: Reflected Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org It was reported some time ago that systems will crash if a driver attempts to access IO port addresses when the PCI IO port region has not been mapped [1]. More recently, a similar crash is where the system PCI host probe fails, and the IPMI driver crashes the system while attempting to do some IO port accesses [2]. This patchset attempts to keep the kernel alive in such situations by 2 complementary methods: 1. Rejecting IO port resource requests until PCI IO port regions have been mapped (in a pci_remap_iospace() call). 2. Rejecting logic PIO access to PCI IO regions until, again, PCI IO port regions have been mapped About 1: Currently the PCI IO port region is initialized to the full range, {0, IO_SPACE_LIMIT}. As such, any IO port region requests would not fail because of PCI IO port regions not being mapped. Patch 1/3 looks to remedy this issue by ensuring IO port requests are made to direct children of ioport_resource (PCI host IO port regions), similar to Arnd's solution, mentioned in [1]: "I see that ioport_resource gets initialized to the {0, IO_SPACE_LIMIT} range. If we could change it so that pci_remap_iospace() hooks up to ioport_resource and extends it whenever something gets mapped there up to IO_SPACE_LIMIT, we can change the default range to {0,0}, which would fail for any request_region call before the first pci_remap_iospace." I didn't use this solution, as logical PIO space is sparse in {0, IO_SPACE_LIMIT}, so we cannot simply grow the region. I marked the patch as RFC, as the solution is not ideal, i.e. calling __release_region() if the region is not suitable. In addition, regressions may be seen, so I would like input first. About 2: Some drivers - like f71805f hwmon driver - do not call request_{muxed_}region() prior to accessing IO port regions, as they should do. So patch 2/3 adds a safeguard against this, in that unwarranted PIO IO accesses will be discarded in the low-level accessors. About the issue of f71805f driver not requesting the IO port region - many drivers do this, and need to be fixed up separately. 1. https://www.spinics.net/lists/linux-pci/msg49821.html 2. https://www.spinics.net/lists/arm-kernel/msg694702.html Differences to v1 patchset: https://lkml.org/lkml/2019/3/14/630 - Drop f71805f fix - it can be done in a separate patchset - Change implementation in resource.c patch to check if parent of region is ioport_resource - Add patch to fix some logic_pio.c prints John Garry (3): resource: Request IO port regions from children of ioport_resource lib: logic_pio: Reject access to unregistered CPU MMIO regions lib: logic_pio: Make some prints explicitly hex include/linux/ioport.h | 12 +++++-- kernel/resource.c | 28 ++++++++++++++++ lib/logic_pio.c | 74 ++++++++++++++++++++++++------------------ 3 files changed, 79 insertions(+), 35 deletions(-)