linux-kernel - [PATCH v1 1/8] iommu: Add iommu_group_replace

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Date:   Thu,  6 Jan 2022 10:20:46 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Robin Murphy <robin.murphy@....com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Will Deacon <will@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
        Diana Craciun <diana.craciun@....nxp.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Li Yang <leoyang.li@....com>,
        Dmitry Osipenko <digetx@...il.com>,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v1 1/8] iommu: Add iommu_group_replace_domain()

Expose an interface to replace the domain of an iommu group for frameworks
like vfio which claims the ownership of the whole iommu group.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/iommu.h | 10 ++++++++++
 drivers/iommu/iommu.c | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 408a6d2b3034..66ebce3d1e11 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -677,6 +677,9 @@ void iommu_device_unuse_dma_api(struct device *dev);
 int iommu_group_set_dma_owner(struct iommu_group *group, void *owner);
 void iommu_group_release_dma_owner(struct iommu_group *group);
 bool iommu_group_dma_owner_claimed(struct iommu_group *group);
+int iommu_group_replace_domain(struct iommu_group *group,
+			       struct iommu_domain *old,
+			       struct iommu_domain *new);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -1090,6 +1093,13 @@ static inline bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 {
 	return false;
 }
+
+static inline int
+iommu_group_replace_domain(struct iommu_group *group, struct iommu_domain *old,
+			   struct iommu_domain *new)
+{
+	return -ENODEV;
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 72a95dea688e..ab8ab95969f5 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3431,3 +3431,40 @@ bool iommu_group_dma_owner_claimed(struct iommu_group *group)
 	return user;
 }
 EXPORT_SYMBOL_GPL(iommu_group_dma_owner_claimed);
+
+/**
+ * iommu_group_replace_domain() - Replace group's domain
+ * @group: The group.
+ * @old: The previous attached domain. NULL for none.
+ * @new: The new domain about to be attached.
+ *
+ * This is to support backward compatibility for vfio which manages the dma
+ * ownership in iommu_group level.
+ */
+int iommu_group_replace_domain(struct iommu_group *group,
+			       struct iommu_domain *old,
+			       struct iommu_domain *new)
+{
+	int ret = 0;
+
+	mutex_lock(&group->mutex);
+	if (!group->owner || group->domain != old) {
+		ret = -EPERM;
+		goto unlock_out;
+	}
+
+	if (old)
+		__iommu_detach_group(old, group);
+
+	if (new) {
+		ret = __iommu_attach_group(new, group);
+		if (ret && old)
+			__iommu_attach_group(old, group);
+	}
+
+unlock_out:
+	mutex_unlock(&group->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_replace_domain);
-- 
2.25.1