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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 6A173C3A589 for ; Thu, 15 Aug 2019 20:10:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 42CE42089E for ; Thu, 15 Aug 2019 20:10:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387586AbfHOUKt (ORCPT ); Thu, 15 Aug 2019 16:10:49 -0400 Received: from mga18.intel.com ([134.134.136.126]:43467 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732526AbfHOUJq (ORCPT ); Thu, 15 Aug 2019 16:09:46 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Aug 2019 13:09:42 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,389,1559545200"; d="scan'208";a="188596199" Received: from jacob-builder.jf.intel.com ([10.7.199.155]) by orsmga002.jf.intel.com with ESMTP; 15 Aug 2019 13:09:42 -0700 From: Jacob Pan To: iommu@lists.linux-foundation.org, LKML , Joerg Roedel , David Woodhouse , Alex Williamson Cc: Eric Auger , "Yi Liu" , "Tian, Kevin" , Raj Ashok , "Christoph Hellwig" , Jean-Philippe Brucker , "Lu Baolu" , Jonathan Cameron Subject: [PATCH v5 01/19] iommu: Add a timeout parameter for PRQ response Date: Thu, 15 Aug 2019 13:13:07 -0700 Message-Id: <1565900005-62508-2-git-send-email-jacob.jun.pan@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1565900005-62508-1-git-send-email-jacob.jun.pan@linux.intel.com> References: <1565900005-62508-1-git-send-email-jacob.jun.pan@linux.intel.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When an I/O page request is processed outside the IOMMU subsystem, response can be delayed or lost. Add a tunable setup parameter such that user can choose the timeout for IOMMU to track pending page requests. This timeout mechanism is a basic safety net which can be implemented in conjunction with credit based or device level page response exception handling. Signed-off-by: Jacob Pan --- Documentation/admin-guide/kernel-parameters.txt | 8 ++++++ drivers/iommu/iommu.c | 33 +++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 47d981a..7da5a83 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1817,6 +1817,14 @@ 1 - Bypass the IOMMU for DMA. unset - Use value of CONFIG_IOMMU_DEFAULT_PASSTHROUGH. + iommu.prq_timeout= + Timeout in seconds to wait for page response + of a pending page request. + Format: + Default: 10 + 0 - no timeout tracking + 1 to 100 - allowed range + io7= [HW] IO7 for Marvel based alpha systems See comment before marvel_specify_io7 in arch/alpha/kernel/core_marvel.c. diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 0c674d8..5b26499 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -33,6 +33,19 @@ static unsigned int iommu_def_domain_type = IOMMU_DOMAIN_DMA; #endif static bool iommu_dma_strict __read_mostly = true; +/* + * Timeout to wait for page response of a pending page request. This is + * intended as a basic safty net in case a pending page request is not + * responded for an exceptionally long time. Device may also implement + * its own protection mechanism against this exception. + * Units are in jiffies with a range between 1 - 100 seconds equivalent. + * Default to 10 seconds. + * Setting 0 means no timeout tracking. + */ +#define IOMMU_PAGE_RESPONSE_MAX_TIMEOUT (HZ * 100) +#define IOMMU_PAGE_RESPONSE_DEF_TIMEOUT (HZ * 10) +static unsigned long prq_timeout = IOMMU_PAGE_RESPONSE_DEF_TIMEOUT; + struct iommu_group { struct kobject kobj; struct kobject *devices_kobj; @@ -176,6 +189,26 @@ static int __init iommu_dma_setup(char *str) } early_param("iommu.strict", iommu_dma_setup); +static int __init iommu_set_prq_timeout(char *str) +{ + int ret; + unsigned long timeout; + + if (!str) + return -EINVAL; + + ret = kstrtoul(str, 10, &timeout); + if (ret) + return ret; + timeout = timeout * HZ; + if (timeout > IOMMU_PAGE_RESPONSE_MAX_TIMEOUT) + return -EINVAL; + prq_timeout = timeout; + + return 0; +} +early_param("iommu.prq_timeout", iommu_set_prq_timeout); + static ssize_t iommu_group_attr_show(struct kobject *kobj, struct attribute *__attr, char *buf) { -- 2.7.4