[PATCH RFC 09/15] vfio/type1: Save domain when attach domain to mdev

[Dave Jiang <dave.jiang@xxxxxxxxx>]

From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

This saves the iommu domain in mdev on attaching a domain
to it and clear it on detaching.

Cc: Ashok Raj <ashok.raj@xxxxxxxxx>
Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Cc: Liu Yi L <yi.l.liu@xxxxxxxxx>
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 drivers/vfio/vfio_iommu_type1.c |   52 ++++++++++++++++++++++++++++++++++++---
 1 file changed, 48 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
index 85b32c325282..40b22c456b06 100644
--- a/drivers/vfio/vfio_iommu_type1.c
+++ b/drivers/vfio/vfio_iommu_type1.c
@@ -1309,20 +1309,62 @@ static struct device *vfio_mdev_get_iommu_device(struct device *dev)
 	return NULL;
 }
 
+static int vfio_mdev_set_domain(struct device *dev, struct iommu_domain *domain)
+{
+	void (*fn)(struct device *dev, void *domain);
+
+	fn = symbol_get(mdev_set_iommu_domain);
+	if (fn) {
+		fn(dev, domain);
+		symbol_put(mdev_set_iommu_domain);
+
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
+static struct iommu_domain *vfio_mdev_get_domain(struct device *dev)
+{
+	void *(*fn)(struct device *dev);
+
+	fn = symbol_get(mdev_get_iommu_domain);
+	if (fn) {
+		struct iommu_domain *domain;
+
+		domain = fn(dev);
+		symbol_put(mdev_get_iommu_domain);
+
+		return domain;
+	}
+
+	return NULL;
+}
+
 static int vfio_mdev_attach_domain(struct device *dev, void *data)
 {
-	struct iommu_domain *domain = data;
+	struct iommu_domain *domain;
 	struct device *iommu_device;
+	int ret = -ENODEV;
+
+	/* Only single domain is allowed to attach to an mdev. */
+	domain = vfio_mdev_get_domain(dev);
+	if (domain)
+		return -EINVAL;
+	domain = data;
 
 	iommu_device = vfio_mdev_get_iommu_device(dev);
 	if (iommu_device) {
 		if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
-			return iommu_aux_attach_device(domain, iommu_device);
+			ret = iommu_aux_attach_device(domain, iommu_device);
 		else
-			return iommu_attach_device(domain, iommu_device);
+			ret = iommu_attach_device(domain, iommu_device);
 	}
 
-	return -EINVAL;
+	if (!ret)
+		vfio_mdev_set_domain(dev, domain);
+
+	return ret;
 }
 
 static int vfio_mdev_detach_domain(struct device *dev, void *data)
@@ -1338,6 +1380,8 @@ static int vfio_mdev_detach_domain(struct device *dev, void *data)
 			iommu_detach_device(domain, iommu_device);
 	}
 
+	vfio_mdev_set_domain(dev, NULL);
+
 	return 0;
 }