[PATCH v2 11/13] samples/vfio-mdev-pci: call vfio_add_group_dev()

Liu Yi L
2019-09-06T08:18:11Z

This patch adds vfio_add_group_dev() calling in probe() to make
vfio-mdev-pci work well with non-singleton iommu group. User could
bind devices from a non-singleton iommu group to either vfio-pci
driver or this sample driver. Existing passthru policy works well
for this non-singleton group.

This is actually a policy choice. A device driver can make this call
if it wants to be vfio viable. And it needs to provide dummy
vfio_device_ops which is required by vfio framework. To prevent user
from opening the device from the iommu backed group fd, the open
callback of the dummy vfio_device_ops should return -ENODEV to fail
the VFIO_GET_DEVICE_FD request from userspace.

Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
---
drivers/vfio/pci/vfio_mdev_pci.c | 91 ++++++++++++++++++++++++++++++++++++----
1 file changed, 82 insertions(+), 9 deletions(-)

diff --git a/drivers/vfio/pci/vfio_mdev_pci.c b/drivers/vfio/pci/vfio_mdev_pci.c
index 09143d3..a61c20d 100644
--- a/drivers/vfio/pci/vfio_mdev_pci.c
+++ b/drivers/vfio/pci/vfio_mdev_pci.c
@@ -107,19 +107,27 @@ struct vfio_mdev_pci {
static int vfio_mdev_pci_create(struct kobject *kobj, struct mdev_device *mdev)
{
struct device *pdev;
+ struct vfio_device *device;
struct vfio_mdev_pci_device *vmdev;
struct vfio_mdev_pci *pmdev;
int ret;

pdev = mdev_parent_dev(mdev);
- vmdev = dev_get_drvdata(pdev);
+ device = vfio_device_get_from_dev(pdev);
+ vmdev = vfio_device_data(device);

- if (atomic_dec_if_positive(&vmdev->avail) < 0)
- return -ENOSPC;
+ if (atomic_dec_if_positive(&vmdev->avail) < 0) {
+ ret = -ENOSPC;
+ goto out;
+ }

+ pr_info("%s, available instance: %d\n",
+ __func__, atomic_read(&vmdev->avail));
pmdev = kzalloc(sizeof(struct vfio_mdev_pci), GFP_KERNEL);
- if (!pmdev)
- return -ENOMEM;
+ if (!pmdev) {
+ ret = -ENOMEM;
+ goto out;
+ }

pmdev->mdev = mdev;
pmdev->vdev = &vmdev->vdev;
@@ -130,10 +138,11 @@ static int vfio_mdev_pci_create(struct kobject *kobj, struct mdev_device *mdev)
__func__, dev_name(mdev_dev(mdev)), dev_name(pdev));
kfree(pmdev);
atomic_inc(&vmdev->avail);
- return ret;
}

- return 0;
+out:
+ vfio_device_put(device);
+ return ret;
}

static int vfio_mdev_pci_remove(struct mdev_device *mdev)
@@ -145,6 +154,8 @@ static int vfio_mdev_pci_remove(struct mdev_device *mdev)

kfree(pmdev);
atomic_inc(&vmdev->avail);
+ pr_info("%s, available instance: %d\n",
+ __func__, atomic_read(&vmdev->avail));
pr_info("%s, succeeded for mdev: %s\n", __func__,
dev_name(mdev_dev(mdev)));

@@ -236,12 +247,65 @@ static ssize_t vfio_mdev_pci_write(struct mdev_device *mdev,
return vfio_pci_write(pmdev->vdev, (char __user *)buf, count, ppos);
}

+static int vfio_pci_dummy_open(void *device_data)
+{
+ struct vfio_mdev_pci_device *vmdev =
+ (struct vfio_mdev_pci_device *) device_data;
+ pr_warn("Device %s is not viable for vfio-pci passthru, please follow"
+ " vfio-mdev passthru path as it has been wrapped as mdev!!!\n",
+ dev_name(&vmdev->vdev.pdev->dev));
+ return -ENODEV;
+}
+
+static void vfio_pci_dummy_release(void *device_data)
+{
+}
+
+long vfio_pci_dummy_ioctl(void *device_data,
+ unsigned int cmd, unsigned long arg)
+{
+ return 0;
+}
+
+ssize_t vfio_pci_dummy_read(void *device_data, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return 0;
+}
+
+ssize_t vfio_pci_dummy_write(void *device_data, const char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ return 0;
+}
+
+int vfio_pci_dummy_mmap(void *device_data, struct vm_area_struct *vma)
+{
+ return 0;
+}
+
+void vfio_pci_dummy_request(void *device_data, unsigned int count)
+{
+}
+
+static const struct vfio_device_ops vfio_pci_dummy_ops = {
+ .name = "vfio-pci",
+ .open = vfio_pci_dummy_open,
+ .release = vfio_pci_dummy_release,
+ .ioctl = vfio_pci_dummy_ioctl,
+ .read = vfio_pci_dummy_read,
+ .write = vfio_pci_dummy_write,
+ .mmap = vfio_pci_dummy_mmap,
+ .request = vfio_pci_dummy_request,
+};
+
static int vfio_mdev_pci_driver_probe(struct pci_dev *pdev,
const struct pci_device_id *id)
{
struct vfio_mdev_pci_device *vmdev;
struct vfio_pci_device *vdev;
const struct mdev_parent_ops *ops;
+ struct iommu_group *group;
int ret;

if (pdev->hdr_type != PCI_HEADER_TYPE_NORMAL)
@@ -260,6 +324,10 @@ static int vfio_mdev_pci_driver_probe(struct pci_dev *pdev,
return -EBUSY;
}

+ group = vfio_iommu_group_get(&pdev->dev);
+ if (!group)
+ return -EINVAL;
+
vmdev = kzalloc(sizeof(*vmdev), GFP_KERNEL);
if (!vmdev)
return -ENOMEM;
@@ -304,7 +372,12 @@ static int vfio_mdev_pci_driver_probe(struct pci_dev *pdev,
#endif
vdev->disable_idle_d3 = disable_idle_d3;

- pci_set_drvdata(pdev, vmdev);
+ ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_dummy_ops, vmdev);
+ if (ret) {
+ vfio_iommu_group_put(group, &pdev->dev);
+ kfree(vmdev);
+ return ret;
+ }

ret = vfio_pci_reflck_attach(vdev);
if (ret) {
@@ -352,7 +425,7 @@ static void vfio_mdev_pci_driver_remove(struct pci_dev *pdev)

mdev_unregister_device(&pdev->dev);

- vmdev = pci_get_drvdata(pdev);
+ vmdev = vfio_del_group_dev(&pdev->dev);
if (!vmdev)
return;

--
2.7.4