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d="scan'208";a="394841270" Received: from allen-box.sh.intel.com (HELO [10.239.159.139]) ([10.239.159.139]) by fmsmga001.fm.intel.com with ESMTP; 29 Jul 2020 19:46:27 -0700 Subject: Re: [PATCH v3 4/4] vfio/type1: Use iommu_aux_at(de)tach_group() APIs To: Alex Williamson References: <20200714055703.5510-1-baolu.lu@linux.intel.com> <20200714055703.5510-5-baolu.lu@linux.intel.com> <20200729143258.22533170@x1.home> From: Lu Baolu Message-ID: Date: Thu, 30 Jul 2020 10:41:32 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200729143258.22533170@x1.home> Content-Language: en-US Cc: Jean-Philippe Brucker , Kevin Tian , Dave Jiang , Ashok Raj , kvm@vger.kernel.org, Cornelia Huck , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Robin Murphy X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" Hi Alex, On 7/30/20 4:32 AM, Alex Williamson wrote: > On Tue, 14 Jul 2020 13:57:03 +0800 > Lu Baolu wrote: > >> Replace iommu_aux_at(de)tach_device() with iommu_aux_at(de)tach_group(). >> It also saves the IOMMU_DEV_FEAT_AUX-capable physcail device in the >> vfio_group data structure so that it could be reused in other places. >> >> Signed-off-by: Lu Baolu >> --- >> drivers/vfio/vfio_iommu_type1.c | 44 ++++++--------------------------- >> 1 file changed, 7 insertions(+), 37 deletions(-) >> >> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c >> index 5e556ac9102a..f8812e68de77 100644 >> --- a/drivers/vfio/vfio_iommu_type1.c >> +++ b/drivers/vfio/vfio_iommu_type1.c >> @@ -100,6 +100,7 @@ struct vfio_dma { >> struct vfio_group { >> struct iommu_group *iommu_group; >> struct list_head next; >> + struct device *iommu_device; >> bool mdev_group; /* An mdev group */ >> bool pinned_page_dirty_scope; >> }; >> @@ -1627,45 +1628,13 @@ static struct device *vfio_mdev_get_iommu_device(struct device *dev) >> return NULL; >> } >> >> -static int vfio_mdev_attach_domain(struct device *dev, void *data) >> -{ >> - struct iommu_domain *domain = data; >> - struct device *iommu_device; >> - >> - iommu_device = vfio_mdev_get_iommu_device(dev); >> - if (iommu_device) { >> - if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX)) >> - return iommu_aux_attach_device(domain, iommu_device); >> - else >> - return iommu_attach_device(domain, iommu_device); >> - } >> - >> - return -EINVAL; >> -} >> - >> -static int vfio_mdev_detach_domain(struct device *dev, void *data) >> -{ >> - struct iommu_domain *domain = data; >> - struct device *iommu_device; >> - >> - iommu_device = vfio_mdev_get_iommu_device(dev); >> - if (iommu_device) { >> - if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX)) >> - iommu_aux_detach_device(domain, iommu_device); >> - else >> - iommu_detach_device(domain, iommu_device); >> - } >> - >> - return 0; >> -} >> - >> static int vfio_iommu_attach_group(struct vfio_domain *domain, >> struct vfio_group *group) >> { >> if (group->mdev_group) >> - return iommu_group_for_each_dev(group->iommu_group, >> - domain->domain, >> - vfio_mdev_attach_domain); >> + return iommu_aux_attach_group(domain->domain, >> + group->iommu_group, >> + group->iommu_device); > > No, we previously iterated all devices in the group and used the aux > interface only when we have an iommu_device supporting aux. If we > simply assume an mdev group only uses an aux domain we break existing > users, ex. SR-IOV VF backed mdevs. Thanks, Oh, yes. Sorry! I didn't consider the physical device backed mdevs cases. Looked into this part of code, it seems that there's a lock issue here. The group->mutex is held in iommu_group_for_each_dev() and will be acquired again in iommu_attach_device(). How about making it like: static int vfio_iommu_attach_group(struct vfio_domain *domain, struct vfio_group *group) { if (group->mdev_group) { struct device *iommu_device = group->iommu_device; if (WARN_ON(!iommu_device)) return -EINVAL; if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX)) return iommu_aux_attach_device(domain->domain, iommu_device); else return iommu_attach_device(domain->domain, iommu_device); } else { return iommu_attach_group(domain->domain, group->iommu_group); } } The caller (vfio_iommu_type1_attach_group) has guaranteed that all mdevs in an iommu group should be derived from a same physical device. Any thoughts? > > Alex Best regards, baolu > > >> else >> return iommu_attach_group(domain->domain, group->iommu_group); >> } >> @@ -1674,8 +1643,8 @@ static void vfio_iommu_detach_group(struct vfio_domain *domain, >> struct vfio_group *group) >> { >> if (group->mdev_group) >> - iommu_group_for_each_dev(group->iommu_group, domain->domain, >> - vfio_mdev_detach_domain); >> + iommu_aux_detach_group(domain->domain, group->iommu_group, >> + group->iommu_device); >> else >> iommu_detach_group(domain->domain, group->iommu_group); >> } >> @@ -2007,6 +1976,7 @@ static int vfio_iommu_type1_attach_group(void *iommu_data, >> return 0; >> } >> >> + group->iommu_device = iommu_device; >> bus = iommu_device->bus; >> } >> > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu