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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 7F2FBC282E3 for ; Sun, 26 May 2019 16:10:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 624F82085A for ; Sun, 26 May 2019 16:10:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728025AbfEZQKq (ORCPT ); Sun, 26 May 2019 12:10:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42416 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728026AbfEZQKo (ORCPT ); Sun, 26 May 2019 12:10:44 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E91B2307D85E; Sun, 26 May 2019 16:10:43 +0000 (UTC) Received: from laptop.redhat.com (ovpn-116-67.ams2.redhat.com [10.36.116.67]) by smtp.corp.redhat.com (Postfix) with ESMTP id 151E15DEE2; Sun, 26 May 2019 16:10:39 +0000 (UTC) From: Eric Auger To: eric.auger.pro@gmail.com, eric.auger@redhat.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, joro@8bytes.org, alex.williamson@redhat.com, jacob.jun.pan@linux.intel.com, yi.l.liu@intel.com, jean-philippe.brucker@arm.com, will.deacon@arm.com, robin.murphy@arm.com Cc: kevin.tian@intel.com, ashok.raj@intel.com, marc.zyngier@arm.com, peter.maydell@linaro.org, vincent.stehle@arm.com Subject: [PATCH v8 05/29] iommu: Add a timeout parameter for PRQ response Date: Sun, 26 May 2019 18:09:40 +0200 Message-Id: <20190526161004.25232-6-eric.auger@redhat.com> In-Reply-To: <20190526161004.25232-1-eric.auger@redhat.com> References: <20190526161004.25232-1-eric.auger@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.48]); Sun, 26 May 2019 16:10:44 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Jacob Pan When an IO page request is processed outside 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 --- .../admin-guide/kernel-parameters.txt | 8 +++++ drivers/iommu/iommu.c | 29 +++++++++++++++++++ 2 files changed, 37 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 138f6664b2e2..b43f0893d252 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1813,6 +1813,14 @@ 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 13b301cfb10f..64e87d56f471 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -45,6 +45,19 @@ 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; @@ -157,6 +170,22 @@ static int __init iommu_dma_setup(char *str) } early_param("iommu.strict", iommu_dma_setup); +static int __init iommu_set_prq_timeout(char *str) +{ + unsigned long timeout; + + if (!str) + return -EINVAL; + timeout = simple_strtoul(str, NULL, 0); + 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) { -- 2.20.1