linux-kernel - [PATCH v2 10/17] iommu: Expose group variants of dma ownership interfaces

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Date:   Sun, 28 Nov 2021 10:50:44 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Cc:     Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
        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>, 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 v2 10/17] iommu: Expose group variants of dma ownership interfaces

The vfio needs to set DMA_OWNER_PRIVATE_DOMAIN_USER for the entire group
when attaching it to a vfio container. Expose group variants of setting/
releasing dma ownership for this purpose.

This also exposes the helper iommu_group_dma_owner_unclaimed() for vfio
to report to userspace if the group is viable to user assignment for
compatibility with VFIO_GROUP_FLAGS_VIABLE.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/iommu.h | 21 ++++++++++++++++
 drivers/iommu/iommu.c | 58 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 79 insertions(+)

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 24676b498f38..afcc07bc8d41 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -701,6 +701,10 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle);
 int iommu_device_set_dma_owner(struct device *dev, enum iommu_dma_owner owner,
 			       void *owner_cookie);
 void iommu_device_release_dma_owner(struct device *dev, enum iommu_dma_owner owner);
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+			      void *owner_cookie);
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner);
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group);
 
 #else /* CONFIG_IOMMU_API */
 
@@ -1117,6 +1121,23 @@ static inline void iommu_device_release_dma_owner(struct device *dev,
 						  enum iommu_dma_owner owner)
 {
 }
+
+static inline int iommu_group_set_dma_owner(struct iommu_group *group,
+					    enum iommu_dma_owner owner,
+					    void *owner_cookie)
+{
+	return -EINVAL;
+}
+
+static inline void iommu_group_release_dma_owner(struct iommu_group *group,
+						 enum iommu_dma_owner owner)
+{
+}
+
+static inline bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+	return false;
+}
 #endif /* CONFIG_IOMMU_API */
 
 /**
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 0cba04a8ea3b..423197db99a9 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -3425,6 +3425,64 @@ static void __iommu_group_release_dma_owner(struct iommu_group *group,
 	}
 }
 
+/**
+ * iommu_group_set_dma_owner() - Set DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA owner type.
+ * @owner_cookie: Caller specified pointer. Could be used for exclusive
+ *                declaration. Could be NULL.
+ *
+ * This is to support backward compatibility for legacy vfio which manages
+ * dma ownership in group level. New invocations on this interface should be
+ * prohibited. Instead, please turn to iommu_device_set_dma_owner().
+ */
+int iommu_group_set_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner,
+			      void *owner_cookie)
+{
+	int ret;
+
+	mutex_lock(&group->mutex);
+	ret = __iommu_group_set_dma_owner(group, owner, owner_cookie);
+	mutex_unlock(&group->mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(iommu_group_set_dma_owner);
+
+/**
+ * iommu_group_release_dma_owner() - Release DMA ownership of a group
+ * @group: The group.
+ * @owner: DMA owner type.
+ *
+ * Release the DMA ownership claimed by iommu_group_set_dma_owner().
+ */
+void iommu_group_release_dma_owner(struct iommu_group *group, enum iommu_dma_owner owner)
+{
+	mutex_lock(&group->mutex);
+	__iommu_group_release_dma_owner(group, owner);
+	mutex_unlock(&group->mutex);
+}
+EXPORT_SYMBOL_GPL(iommu_group_release_dma_owner);
+
+/**
+ * iommu_group_dma_owner_unclaimed() - Is group dma ownership claimed
+ * @group: The group.
+ *
+ * This provides status check on a given group. It is racey and only for
+ * non-binding status reporting.
+ */
+bool iommu_group_dma_owner_unclaimed(struct iommu_group *group)
+{
+	enum iommu_dma_owner owner;
+
+	mutex_lock(&group->mutex);
+	owner = group->dma_owner;
+	mutex_unlock(&group->mutex);
+
+	return owner == DMA_OWNER_NONE;
+}
+EXPORT_SYMBOL_GPL(iommu_group_dma_owner_unclaimed);
+
 /**
  * iommu_device_set_dma_owner() - Set DMA ownership of a device
  * @dev: The device.
-- 
2.25.1