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 autolearn=ham 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 A1F59C04AB4 for ; Thu, 16 May 2019 09:32:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7EFCF21734 for ; Thu, 16 May 2019 09:32:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727027AbfEPJc6 (ORCPT ); Thu, 16 May 2019 05:32:58 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44832 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726363AbfEPJc6 (ORCPT ); Thu, 16 May 2019 05:32:58 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 384CA99DDC; Thu, 16 May 2019 09:32:57 +0000 (UTC) Received: from [10.36.116.17] (ovpn-116-17.ams2.redhat.com [10.36.116.17]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 472994D748; Thu, 16 May 2019 09:32:52 +0000 (UTC) Subject: Re: [PATCH v2 6/7] iommu: Introduce IOMMU_RESV_DIRECT_RELAXABLE reserved memory regions To: eric.auger.pro@gmail.com, joro@8bytes.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, dwmw2@infradead.org, lorenzo.pieralisi@arm.com, robin.murphy@arm.com, will.deacon@arm.com, hanjun.guo@linaro.org, sudeep.holla@arm.com Cc: alex.williamson@redhat.com, shameerali.kolothum.thodi@huawei.com References: <20190516084720.10498-1-eric.auger@redhat.com> <20190516084720.10498-7-eric.auger@redhat.com> From: Auger Eric Message-ID: Date: Thu, 16 May 2019 11:32:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190516084720.10498-7-eric.auger@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.38]); Thu, 16 May 2019 09:32:57 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi On 5/16/19 10:47 AM, Eric Auger wrote: > Introduce a new type for reserved region. This corresponds > to directly mapped regions which are known to be relaxable > in some specific conditions, such as device assignment use > case. Well known examples are those used by USB controllers > providing PS/2 keyboard emulation for pre-boot BIOS and > early BOOT or RMRRs associated to IGD working in legacy mode. > > Since commit c875d2c1b808 ("iommu/vt-d: Exclude devices using RMRRs > from IOMMU API domains") and commit 18436afdc11a ("iommu/vt-d: Allow > RMRR on graphics devices too"), those regions are currently > considered "safe" with respect to device assignment use case > which requires a non direct mapping at IOMMU physical level > (RAM GPA -> HPA mapping). > > Those RMRRs currently exist and sometimes the device is > attempting to access it but this has not been considered > an issue until now. > > However at the moment, iommu_get_group_resv_regions() is > not able to make any difference between directly mapped > regions: those which must be absolutely enforced and those > like above ones which are known as relaxable. > > This is a blocker for reporting severe conflicts between > non relaxable RMRRs (like MSI doorbells) and guest GPA space. > > With this new reserved region type we will be able to use > iommu_get_group_resv_regions() to enumerate the IOVA space > that is usable through the IOMMU API without introducing > regressions with respect to existing device assignment > use cases (USB and IGD). > > Signed-off-by: Eric Auger > > --- > > Note: At the moment the sysfs ABI is not changed. However I wonder > whether it wouldn't be preferable to report the direct region as > "direct_relaxed" there. At the moment, in case the same direct > region is used by 2 devices, one USB/GFX and another not belonging > to the previous categories, the direct region will be output twice > with "direct" type. > > This would unblock Shameer's series: > [PATCH v6 0/7] vfio/type1: Add support for valid iova list management > https://patchwork.kernel.org/patch/10425309/ > > which failed to get pulled for 4.18 merge window due to IGD > device assignment regression. > --- > drivers/iommu/iommu.c | 12 +++++++----- > include/linux/iommu.h | 6 ++++++ > 2 files changed, 13 insertions(+), 5 deletions(-) > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index ae4ea5c0e6f9..84dcb6af6511 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -73,10 +73,11 @@ struct iommu_group_attribute { > }; > > static const char * const iommu_group_resv_type_string[] = { > - [IOMMU_RESV_DIRECT] = "direct", > - [IOMMU_RESV_RESERVED] = "reserved", > - [IOMMU_RESV_MSI] = "msi", > - [IOMMU_RESV_SW_MSI] = "msi", > + [IOMMU_RESV_DIRECT] = "direct", > + [IOMMU_RESV_DIRECT_RELAXABLE] = "direct", > + [IOMMU_RESV_RESERVED] = "reserved", > + [IOMMU_RESV_MSI] = "msi", > + [IOMMU_RESV_SW_MSI] = "msi", > }; > > #define IOMMU_GROUP_ATTR(_name, _mode, _show, _store) \ > @@ -573,7 +574,8 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group, > start = ALIGN(entry->start, pg_size); > end = ALIGN(entry->start + entry->length, pg_size); > > - if (entry->type != IOMMU_RESV_DIRECT) > + if (entry->type != IOMMU_RESV_DIRECT || It must be a "&&" and not "||" Respinning ... Eric > + entry->type != IOMMU_RESV_DIRECT_RELAXABLE) > continue; > > for (addr = start; addr < end; addr += pg_size) { > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index ba91666998fb..14a521f85f14 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -135,6 +135,12 @@ enum iommu_attr { > enum iommu_resv_type { > /* Memory regions which must be mapped 1:1 at all times */ > IOMMU_RESV_DIRECT, > + /* > + * Memory regions which are advertised to be 1:1 but are > + * commonly considered relaxable in some conditions, > + * for instance in device assignment use case (USB, Graphics) > + */ > + IOMMU_RESV_DIRECT_RELAXABLE, > /* Arbitrary "never map this or give it to a device" address ranges */ > IOMMU_RESV_RESERVED, > /* Hardware MSI region (untranslated) */ >