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d="scan'208";a="460289202" Received: from allen-box.sh.intel.com (HELO [10.239.159.139]) ([10.239.159.139]) by orsmga005.jf.intel.com with ESMTP; 15 Jul 2020 18:12:23 -0700 Subject: Re: [PATCH v3 2/4] iommu: Add iommu_aux_at(de)tach_group() To: Jacob Pan References: <20200714055703.5510-1-baolu.lu@linux.intel.com> <20200714055703.5510-3-baolu.lu@linux.intel.com> <20200714093909.1ab93c9e@jacob-builder> <20200715090114.50a459d4@jacob-builder> From: Lu Baolu Message-ID: <435a2014-c2e8-06b9-3c9a-4afbf6607ffe@linux.intel.com> Date: Thu, 16 Jul 2020 09:07:46 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <20200715090114.50a459d4@jacob-builder> 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, Alex Williamson , 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 Jacob, On 7/16/20 12:01 AM, Jacob Pan wrote: > On Wed, 15 Jul 2020 08:47:36 +0800 > Lu Baolu wrote: > >> Hi Jacob, >> >> On 7/15/20 12:39 AM, Jacob Pan wrote: >>> On Tue, 14 Jul 2020 13:57:01 +0800 >>> Lu Baolu wrote: >>> >>>> This adds two new aux-domain APIs for a use case like vfio/mdev >>>> where sub-devices derived from an aux-domain capable device are >>>> created and put in an iommu_group. >>>> >>>> /** >>>> * iommu_aux_attach_group - attach an aux-domain to an iommu_group >>>> which >>>> * contains sub-devices (for example >>>> mdevs) derived >>>> * from @dev. >>>> * @domain: an aux-domain; >>>> * @group: an iommu_group which contains sub-devices derived from >>>> @dev; >>>> * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX. >>>> * >>>> * Returns 0 on success, or an error value. >>>> */ >>>> int iommu_aux_attach_group(struct iommu_domain *domain, >>>> struct iommu_group *group, >>>> struct device *dev) >>>> >>>> /** >>>> * iommu_aux_detach_group - detach an aux-domain from an >>>> iommu_group * >>>> * @domain: an aux-domain; >>>> * @group: an iommu_group which contains sub-devices derived from >>>> @dev; >>>> * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX. >>>> * >>>> * @domain must have been attached to @group via >>>> iommu_aux_attach_group(). */ >>>> void iommu_aux_detach_group(struct iommu_domain *domain, >>>> struct iommu_group *group, >>>> struct device *dev) >>>> >>>> It also adds a flag in the iommu_group data structure to identify >>>> an iommu_group with aux-domain attached from those normal ones. >>>> >>>> Signed-off-by: Lu Baolu >>>> --- >>>> drivers/iommu/iommu.c | 58 >>>> +++++++++++++++++++++++++++++++++++++++++++ include/linux/iommu.h | >>>> 17 +++++++++++++ 2 files changed, 75 insertions(+) >>>> >>>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>>> index e1fdd3531d65..cad5a19ebf22 100644 >>>> --- a/drivers/iommu/iommu.c >>>> +++ b/drivers/iommu/iommu.c >>>> @@ -45,6 +45,7 @@ struct iommu_group { >>>> struct iommu_domain *default_domain; >>>> struct iommu_domain *domain; >>>> struct list_head entry; >>>> + unsigned int aux_domain_attached:1; >>>> }; >>>> >>>> struct group_device { >>>> @@ -2759,6 +2760,63 @@ int iommu_aux_get_pasid(struct iommu_domain >>>> *domain, struct device *dev) } >>>> EXPORT_SYMBOL_GPL(iommu_aux_get_pasid); >>>> >>>> +/** >>>> + * iommu_aux_attach_group - attach an aux-domain to an iommu_group >>>> which >>>> + * contains sub-devices (for example >>>> mdevs) derived >>>> + * from @dev. >>>> + * @domain: an aux-domain; >>>> + * @group: an iommu_group which contains sub-devices derived from >>>> @dev; >>>> + * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX. >>>> + * >>>> + * Returns 0 on success, or an error value. >>>> + */ >>>> +int iommu_aux_attach_group(struct iommu_domain *domain, >>>> + struct iommu_group *group, struct >>>> device *dev) +{ >>>> + int ret = -EBUSY; >>>> + >>>> + mutex_lock(&group->mutex); >>>> + if (group->domain) >>>> + goto out_unlock; >>>> + >>> Perhaps I missed something but are we assuming only one mdev per >>> mdev group? That seems to change the logic where vfio does: >>> iommu_group_for_each_dev() >>> iommu_aux_attach_device() >>> >> >> It has been changed in PATCH 4/4: >> >> static int vfio_iommu_attach_group(struct vfio_domain *domain, >> struct vfio_group *group) >> { >> if (group->mdev_group) >> return iommu_aux_attach_group(domain->domain, >> group->iommu_group, >> group->iommu_device); >> else >> return iommu_attach_group(domain->domain, >> group->iommu_group); >> } >> >> So, for both normal domain and aux-domain, we use the same concept: >> attach a domain to a group. >> > I get that, but don't you have to attach all the devices within the This iommu_group includes only mediated devices derived from an IOMMU_DEV_FEAT_AUX-capable device. Different from iommu_attach_group(), iommu_aux_attach_group() doesn't need to attach the domain to each device in group, instead it only needs to attach the domain to the physical device where the mdev's were created from. > group? Here you see the group already has a domain and exit. If the (group->domain) has been set, that means a domain has already attached to the group, so it returns -EBUSY. Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu