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_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 284E7C43381 for ; Fri, 22 Mar 2019 09:30:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E06FE218D3 for ; Fri, 22 Mar 2019 09:30:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727865AbfCVJaM (ORCPT ); Fri, 22 Mar 2019 05:30:12 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36486 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727713AbfCVJaL (ORCPT ); Fri, 22 Mar 2019 05:30:11 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A810A307CDEA; Fri, 22 Mar 2019 09:30:10 +0000 (UTC) Received: from [10.36.116.167] (ovpn-116-167.ams2.redhat.com [10.36.116.167]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 8FC48604C7; Fri, 22 Mar 2019 09:30:04 +0000 (UTC) Subject: Re: [PATCH v6 09/22] vfio: VFIO_IOMMU_BIND/UNBIND_MSI To: Alex Williamson Cc: eric.auger.pro@gmail.com, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, joro@8bytes.org, jacob.jun.pan@linux.intel.com, yi.l.liu@linux.intel.com, jean-philippe.brucker@arm.com, will.deacon@arm.com, robin.murphy@arm.com, kevin.tian@intel.com, ashok.raj@intel.com, marc.zyngier@arm.com, christoffer.dall@arm.com, peter.maydell@linaro.org, vincent.stehle@arm.com References: <20190317172232.1068-1-eric.auger@redhat.com> <20190317172232.1068-10-eric.auger@redhat.com> <20190321170159.38358f38@x1.home> From: Auger Eric Message-ID: <16931d58-9c88-8cfb-a392-408ea7afdf16@redhat.com> Date: Fri, 22 Mar 2019 10:30:02 +0100 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: <20190321170159.38358f38@x1.home> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Fri, 22 Mar 2019 09:30:11 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Alex, On 3/22/19 12:01 AM, Alex Williamson wrote: > On Sun, 17 Mar 2019 18:22:19 +0100 > Eric Auger wrote: > >> This patch adds the VFIO_IOMMU_BIND/UNBIND_MSI ioctl which aim >> to pass/withdraw the guest MSI binding to/from the host. >> >> Signed-off-by: Eric Auger >> >> --- >> v3 -> v4: >> - add UNBIND >> - unwind on BIND error >> >> v2 -> v3: >> - adapt to new proto of bind_guest_msi >> - directly use vfio_iommu_for_each_dev >> >> v1 -> v2: >> - s/vfio_iommu_type1_guest_msi_binding/vfio_iommu_type1_bind_guest_msi >> --- >> drivers/vfio/vfio_iommu_type1.c | 58 +++++++++++++++++++++++++++++++++ >> include/uapi/linux/vfio.h | 29 +++++++++++++++++ >> 2 files changed, 87 insertions(+) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 12a40b9db6aa..66513679081b 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -1710,6 +1710,25 @@ static int vfio_cache_inv_fn(struct device *dev, void *data) >> return iommu_cache_invalidate(d, dev, &ustruct->info); >> } >> >> +static int vfio_bind_msi_fn(struct device *dev, void *data) >> +{ >> + struct vfio_iommu_type1_bind_msi *ustruct = >> + (struct vfio_iommu_type1_bind_msi *)data; >> + struct iommu_domain *d = iommu_get_domain_for_dev(dev); >> + >> + return iommu_bind_guest_msi(d, dev, ustruct->iova, >> + ustruct->gpa, ustruct->size); >> +} >> + >> +static int vfio_unbind_msi_fn(struct device *dev, void *data) >> +{ >> + dma_addr_t *iova = (dma_addr_t *)data; >> + struct iommu_domain *d = iommu_get_domain_for_dev(dev); > > Same as previous, we can encapsulate domain in our own struct to avoid > a lookup. > >> + >> + iommu_unbind_guest_msi(d, dev, *iova); > > Is it strange that iommu-core is exposing these interfaces at a device > level if every one of them requires us to walk all the devices? Thanks, Hum this per device API was devised in response of Robin's comments on [RFC v2 12/20] dma-iommu: Implement NESTED_MSI cookie. " But that then seems to reveal a somewhat bigger problem - if the callers are simply registering IPAs, and relying on the ITS driver to grab an entry and fill in a PA later, then how does either one know *which* PA is supposed to belong to a given IPA in the case where you have multiple devices with different ITS targets assigned to the same guest? (and if it's possible to assume a guest will use per-device stage 1 mappings and present it with a single vITS backed by multiple pITSes, I think things start breaking even harder.) " However looking back into the problem I wonder if there was an issue with the iommu_domain based API. If my understanding is correct, when assigned devices are protected by a vIOMMU then they necessarily end up in separate host iommu domains even if they belong to the same iommu_domain on the guest. And there can only be a single device in this iommu_domain. If this is confirmed, there is a non ambiguous association between 1 physical iommu_domain, 1 device, 1 S1 mapping and 1 physical MSI controller. I added the device handle handle to disambiguate those associations. The gIOVA ->gDB mapping is associated with a device handle. Then when the host needs a stage 1 mapping for this device, to build the nested mapping towards the physical DB it can easily grab the gIOVA->gDB stage 1 mapping registered for this device. The correctness looks more obvious to me, at least. Thanks Eric > > Alex > >> + return 0; >> +} >> + >> static long vfio_iommu_type1_ioctl(void *iommu_data, >> unsigned int cmd, unsigned long arg) >> { >> @@ -1814,6 +1833,45 @@ static long vfio_iommu_type1_ioctl(void *iommu_data, >> vfio_cache_inv_fn); >> mutex_unlock(&iommu->lock); >> return ret; >> + } else if (cmd == VFIO_IOMMU_BIND_MSI) { >> + struct vfio_iommu_type1_bind_msi ustruct; >> + int ret; >> + >> + minsz = offsetofend(struct vfio_iommu_type1_bind_msi, >> + size); >> + >> + if (copy_from_user(&ustruct, (void __user *)arg, minsz)) >> + return -EFAULT; >> + >> + if (ustruct.argsz < minsz || ustruct.flags) >> + return -EINVAL; >> + >> + mutex_lock(&iommu->lock); >> + ret = vfio_iommu_for_each_dev(iommu, &ustruct, >> + vfio_bind_msi_fn); >> + if (ret) >> + vfio_iommu_for_each_dev(iommu, &ustruct.iova, >> + vfio_unbind_msi_fn); >> + mutex_unlock(&iommu->lock); >> + return ret; >> + } else if (cmd == VFIO_IOMMU_UNBIND_MSI) { >> + struct vfio_iommu_type1_unbind_msi ustruct; >> + int ret; >> + >> + minsz = offsetofend(struct vfio_iommu_type1_unbind_msi, >> + iova); >> + >> + if (copy_from_user(&ustruct, (void __user *)arg, minsz)) >> + return -EFAULT; >> + >> + if (ustruct.argsz < minsz || ustruct.flags) >> + return -EINVAL; >> + >> + mutex_lock(&iommu->lock); >> + ret = vfio_iommu_for_each_dev(iommu, &ustruct.iova, >> + vfio_unbind_msi_fn); >> + mutex_unlock(&iommu->lock); >> + return ret; >> } >> >> return -ENOTTY; >> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h >> index 29f0ef2d805d..6763389b6adc 100644 >> --- a/include/uapi/linux/vfio.h >> +++ b/include/uapi/linux/vfio.h >> @@ -789,6 +789,35 @@ struct vfio_iommu_type1_cache_invalidate { >> }; >> #define VFIO_IOMMU_CACHE_INVALIDATE _IO(VFIO_TYPE, VFIO_BASE + 24) >> >> +/** >> + * VFIO_IOMMU_BIND_MSI - _IOWR(VFIO_TYPE, VFIO_BASE + 25, >> + * struct vfio_iommu_type1_bind_msi) >> + * >> + * Pass a stage 1 MSI doorbell mapping to the host so that this >> + * latter can build a nested stage2 mapping >> + */ >> +struct vfio_iommu_type1_bind_msi { >> + __u32 argsz; >> + __u32 flags; >> + __u64 iova; >> + __u64 gpa; >> + __u64 size; >> +}; >> +#define VFIO_IOMMU_BIND_MSI _IO(VFIO_TYPE, VFIO_BASE + 25) >> + >> +/** >> + * VFIO_IOMMU_UNBIND_MSI - _IOWR(VFIO_TYPE, VFIO_BASE + 26, >> + * struct vfio_iommu_type1_unbind_msi) >> + * >> + * Unregister an MSI mapping >> + */ >> +struct vfio_iommu_type1_unbind_msi { >> + __u32 argsz; >> + __u32 flags; >> + __u64 iova; >> +}; >> +#define VFIO_IOMMU_UNBIND_MSI _IO(VFIO_TYPE, VFIO_BASE + 26) >> + >> /* -------- Additional API for SPAPR TCE (Server POWERPC) IOMMU -------- */ >> >> /* >