[PATCH v1 1/8] iommu: Add iommu_group_replace_domain()

From: Lu Baolu <baolu.lu@linux.intel.com>
To: Joerg Roedel <joro@8bytes.org>,
	Alex Williamson <alex.williamson@redhat.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Christoph Hellwig <hch@infradead.org>,
	Kevin Tian <kevin.tian@intel.com>,
	Ashok Raj <ashok.raj@intel.com>
Cc: kvm@vger.kernel.org, rafael@kernel.org,
	David Airlie <airlied@linux.ie>,
	linux-pci@vger.kernel.org,
	Thierry Reding <thierry.reding@gmail.com>,
	Diana Craciun <diana.craciun@oss.nxp.com>,
	Dmitry Osipenko <digetx@gmail.com>, Will Deacon <will@kernel.org>,
	Stuart Yoder <stuyoder@gmail.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Chaitanya Kulkarni <kch@nvidia.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Cornelia Huck <cohuck@redhat.com>,
	linux-kernel@vger.kernel.org, Li Yang <leoyang.li@nxp.com>,
	iommu@lists.linux-foundation.org,
	Jacob jun Pan <jacob.jun.pan@intel.com>,
	Daniel Vetter <daniel@ffwll.ch>
Subject: [PATCH v1 1/8] iommu: Add iommu_group_replace_domain()
Date: Thu,  6 Jan 2022 10:20:46 +0800	[thread overview]
Message-ID: <20220106022053.2406748-2-baolu.lu@linux.intel.com> (raw)
In-Reply-To: <20220106022053.2406748-1-baolu.lu@linux.intel.com>

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@linux.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

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