linux-kernel - [PATCH V4 12/18] iommu/vt-d: Remove mm reference for guest SVA

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Date:   Sat, 27 Feb 2021 14:01:20 -0800
From:   Jacob Pan <jacob.jun.pan@...ux.intel.com>
To:     LKML <linux-kernel@...r.kernel.org>,
        Joerg Roedel <joro@...tes.org>,
        "Lu Baolu" <baolu.lu@...ux.intel.com>,
        David Woodhouse <dwmw2@...radead.org>,
        iommu@...ts.linux-foundation.org, cgroups@...r.kernel.org,
        Tejun Heo <tj@...nel.org>, Li Zefan <lizefan@...wei.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Jean-Philippe Brucker <jean-philippe@...aro.com>
Cc:     Alex Williamson <alex.williamson@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Jonathan Corbet <corbet@....net>,
        Raj Ashok <ashok.raj@...el.com>,
        "Tian, Kevin" <kevin.tian@...el.com>, Yi Liu <yi.l.liu@...el.com>,
        Wu Hao <hao.wu@...el.com>, Dave Jiang <dave.jiang@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>
Subject: [PATCH V4 12/18] iommu/vt-d: Remove mm reference for guest SVA

Now that IOASID core keeps track of the IOASID to mm_struct ownership in
the forms of ioasid_set with IOASID_SET_TYPE_MM token type, there is no
need to keep the same mapping in VT-d driver specific data. Native SVM
usage is not affected by the change.

Signed-off-by: Jacob Pan <jacob.jun.pan@...ux.intel.com>
---
 drivers/iommu/intel/svm.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index c469c24d23f5..f75699ddb923 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -363,12 +363,6 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
 			ret = -ENOMEM;
 			goto out;
 		}
-		/* REVISIT: upper layer/VFIO can track host process that bind
-		 * the PASID. ioasid_set = mm might be sufficient for vfio to
-		 * check pasid VMM ownership. We can drop the following line
-		 * once VFIO and IOASID set check is in place.
-		 */
-		svm->mm = get_task_mm(current);
 		svm->pasid = data->hpasid;
 		if (data->flags & IOMMU_SVA_GPASID_VAL) {
 			svm->gpasid = data->gpasid;
@@ -376,7 +370,6 @@ int intel_svm_bind_gpasid(struct iommu_domain *domain, struct device *dev,
 		}
 		ioasid_attach_data(data->hpasid, svm);
 		INIT_LIST_HEAD_RCU(&svm->devs);
-		mmput(svm->mm);
 	}
 	sdev = kzalloc(sizeof(*sdev), GFP_KERNEL);
 	if (!sdev) {
-- 
2.25.1