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 DE9CAC282CE for ; Mon, 3 Jun 2019 22:32:20 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id A348826AD3 for ; Mon, 3 Jun 2019 22:32:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A348826AD3 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 58DF84A3B4; Mon, 3 Jun 2019 18:32:20 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ybejVlcyWDmY; Mon, 3 Jun 2019 18:32:18 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 363444A418; Mon, 3 Jun 2019 18:32:18 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 9DFE24A3B4 for ; Mon, 3 Jun 2019 18:32:17 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Em0B4XxSnVxa for ; Mon, 3 Jun 2019 18:32:16 -0400 (EDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 783E94A369 for ; Mon, 3 Jun 2019 18:32:16 -0400 (EDT) Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id CC2D530C0DED; Mon, 3 Jun 2019 22:32:15 +0000 (UTC) Received: from x1.home (ovpn-116-22.phx2.redhat.com [10.3.116.22]) by smtp.corp.redhat.com (Postfix) with ESMTP id C188E1001DE0; Mon, 3 Jun 2019 22:32:14 +0000 (UTC) Date: Mon, 3 Jun 2019 16:32:14 -0600 From: Alex Williamson To: Eric Auger Subject: Re: [PATCH v8 05/29] iommu: Add a timeout parameter for PRQ response Message-ID: <20190603163214.483884a7@x1.home> In-Reply-To: <20190526161004.25232-6-eric.auger@redhat.com> References: <20190526161004.25232-1-eric.auger@redhat.com> <20190526161004.25232-6-eric.auger@redhat.com> Organization: Red Hat MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.45]); Mon, 03 Jun 2019 22:32:16 +0000 (UTC) Cc: kevin.tian@intel.com, jacob.jun.pan@linux.intel.com, ashok.raj@intel.com, kvm@vger.kernel.org, joro@8bytes.org, will.deacon@arm.com, linux-kernel@vger.kernel.org, marc.zyngier@arm.com, iommu@lists.linux-foundation.org, yi.l.liu@intel.com, vincent.stehle@arm.com, robin.murphy@arm.com, kvmarm@lists.cs.columbia.edu, eric.auger.pro@gmail.com X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Sun, 26 May 2019 18:09:40 +0200 Eric Auger wrote: > 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) > { It doesn't seem to make much sense to include this patch without also including "iommu: handle page response timeout". Was that one lost? Dropped? Lives elsewhere? Thanks, Alex _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm