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Subject[RFC PATCH 02/10] vfio: Update vfio_add_group_dev() API
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Rather than an errno, return a pointer to the opaque vfio_device
to allow the bus driver to call into vfio-core without additional
lookups and references. Note that bus drivers are still required
to use vfio_del_group_dev() to teardown the vfio_device.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
drivers/vfio/fsl-mc/vfio_fsl_mc.c | 6 ++++--
drivers/vfio/mdev/vfio_mdev.c | 5 ++++-
drivers/vfio/pci/vfio_pci.c | 7 +++++--
drivers/vfio/platform/vfio_platform_common.c | 7 +++++--
drivers/vfio/vfio.c | 23 ++++++++++-------------
include/linux/vfio.h | 6 +++---
6 files changed, 31 insertions(+), 23 deletions(-)

diff --git a/drivers/vfio/fsl-mc/vfio_fsl_mc.c b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
index f27e25112c40..a4c2d0b9cd51 100644
--- a/drivers/vfio/fsl-mc/vfio_fsl_mc.c
+++ b/drivers/vfio/fsl-mc/vfio_fsl_mc.c
@@ -592,6 +592,7 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)
struct iommu_group *group;
struct vfio_fsl_mc_device *vdev;
struct device *dev = &mc_dev->dev;
+ struct vfio_device *device;
int ret;

group = vfio_iommu_group_get(dev);
@@ -608,8 +609,9 @@ static int vfio_fsl_mc_probe(struct fsl_mc_device *mc_dev)

vdev->mc_dev = mc_dev;

- ret = vfio_add_group_dev(dev, &vfio_fsl_mc_ops, vdev);
- if (ret) {
+ device = vfio_add_group_dev(dev, &vfio_fsl_mc_ops, vdev);
+ if (IS_ERR(device)) {
+ ret = PTR_ERR(device);
dev_err(dev, "VFIO_FSL_MC: Failed to add to vfio group\n");
goto out_group_put;
}
diff --git a/drivers/vfio/mdev/vfio_mdev.c b/drivers/vfio/mdev/vfio_mdev.c
index b52eea128549..32901b265864 100644
--- a/drivers/vfio/mdev/vfio_mdev.c
+++ b/drivers/vfio/mdev/vfio_mdev.c
@@ -124,8 +124,11 @@ static const struct vfio_device_ops vfio_mdev_dev_ops = {
static int vfio_mdev_probe(struct device *dev)
{
struct mdev_device *mdev = to_mdev_device(dev);
+ struct vfio_device *device;

- return vfio_add_group_dev(dev, &vfio_mdev_dev_ops, mdev);
+ device = vfio_add_group_dev(dev, &vfio_mdev_dev_ops, mdev);
+
+ return IS_ERR(device) ? PTR_ERR(device) : 0;
}

static void vfio_mdev_remove(struct device *dev)
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 65e7e6b44578..f0a1d05f0137 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1926,6 +1926,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct vfio_pci_device *vdev;
struct iommu_group *group;
+ struct vfio_device *device;
int ret;

if (vfio_pci_is_denylisted(pdev))
@@ -1968,9 +1969,11 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
INIT_LIST_HEAD(&vdev->vma_list);
init_rwsem(&vdev->memory_lock);

- ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
- if (ret)
+ device = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
+ if (IS_ERR(device)) {
+ ret = PTR_ERR(device);
goto out_free;
+ }

ret = vfio_pci_reflck_attach(vdev);
if (ret)
diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index fb4b385191f2..ff41fe0b758e 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -657,6 +657,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
struct device *dev)
{
struct iommu_group *group;
+ struct vfio_device *device;
int ret;

if (!vdev)
@@ -685,9 +686,11 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev,
goto put_reset;
}

- ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
- if (ret)
+ device = vfio_add_group_dev(dev, &vfio_platform_ops, vdev);
+ if (IS_ERR(device)) {
+ ret = PTR_ERR(device);
goto put_iommu;
+ }

mutex_init(&vdev->igate);

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 464caef97aff..067cd843961c 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -848,8 +848,9 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
/**
* VFIO driver API
*/
-int vfio_add_group_dev(struct device *dev,
- const struct vfio_device_ops *ops, void *device_data)
+struct vfio_device *vfio_add_group_dev(struct device *dev,
+ const struct vfio_device_ops *ops,
+ void *device_data)
{
struct iommu_group *iommu_group;
struct vfio_group *group;
@@ -857,14 +858,14 @@ int vfio_add_group_dev(struct device *dev,

iommu_group = iommu_group_get(dev);
if (!iommu_group)
- return -EINVAL;
+ return ERR_PTR(-EINVAL);

group = vfio_group_get_from_iommu(iommu_group);
if (!group) {
group = vfio_create_group(iommu_group);
if (IS_ERR(group)) {
iommu_group_put(iommu_group);
- return PTR_ERR(group);
+ return (struct vfio_device *)group;
}
} else {
/*
@@ -880,23 +881,19 @@ int vfio_add_group_dev(struct device *dev,
iommu_group_id(iommu_group));
vfio_device_put(device);
vfio_group_put(group);
- return -EBUSY;
+ return ERR_PTR(-EBUSY);
}

device = vfio_group_create_device(group, dev, ops, device_data);
- if (IS_ERR(device)) {
- vfio_group_put(group);
- return PTR_ERR(device);
- }

/*
- * Drop all but the vfio_device reference. The vfio_device holds
- * a reference to the vfio_group, which holds a reference to the
- * iommu_group.
+ * Drop all but the vfio_device reference. The vfio_device, if
+ * !IS_ERR() holds a reference to the vfio_group, which holds a
+ * reference to the iommu_group.
*/
vfio_group_put(group);

- return 0;
+ return device;
}
EXPORT_SYMBOL_GPL(vfio_add_group_dev);

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index b7e18bde5aa8..b784463000d4 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -48,9 +48,9 @@ struct vfio_device_ops {
extern struct iommu_group *vfio_iommu_group_get(struct device *dev);
extern void vfio_iommu_group_put(struct iommu_group *group, struct device *dev);

-extern int vfio_add_group_dev(struct device *dev,
- const struct vfio_device_ops *ops,
- void *device_data);
+extern struct vfio_device *vfio_add_group_dev(struct device *dev,
+ const struct vfio_device_ops *ops,
+ void *device_data);

extern void *vfio_del_group_dev(struct device *dev);
extern struct vfio_device *vfio_device_get_from_dev(struct device *dev);
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