RE: [PATCH v2 10/13] samples: refine vfio-mdev-pci driver

[Liu, Yi L]

Hi Alex,

> From: Alex Williamson [mailto:alex.williamson@xxxxxxxxxx]
> Sent: Thursday, September 26, 2019 10:37 AM
> To: Liu, Yi L <yi.l.liu@xxxxxxxxx>
>
> Subject: Re: [PATCH v2 10/13] samples: refine vfio-mdev-pci driver
> 
> On Thu,  5 Sep 2019 15:59:27 +0800
> Liu Yi L <yi.l.liu@xxxxxxxxx> wrote:
> 
> > From: Alex Williamson <alex.williamson@xxxxxxxxxx>
> >
> > This patch refines the implementation of original vfio-mdev-pci driver.
> >
> > And the vfio-mdev-pci-type_name will be named per the following rule:
> >
> > 	vmdev->attr.name = kasprintf(GFP_KERNEL,
> > 				     "%04x:%04x:%04x:%04x:%06x:%02x",
> > 				     pdev->vendor, pdev->device,
> > 				     pdev->subsystem_vendor,
> > 				     pdev->subsystem_device, pdev->class,
> > 				     pdev->revision);
> >
> > Before usage, check the
> > /sys/bus/pci/devices/$bdf/mdev_supported_types/
> > to ensure the final mdev_supported_types.
> >
> > Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
> > Cc: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
> > ---
> >  drivers/vfio/pci/vfio_mdev_pci.c | 123
> > +++++++++++++++++++++++----------------
> >  1 file changed, 72 insertions(+), 51 deletions(-)
> >
> > diff --git a/drivers/vfio/pci/vfio_mdev_pci.c
> > b/drivers/vfio/pci/vfio_mdev_pci.c
> > index 07c8067..09143d3 100644
> > --- a/drivers/vfio/pci/vfio_mdev_pci.c
> > +++ b/drivers/vfio/pci/vfio_mdev_pci.c
> > @@ -65,18 +65,22 @@ MODULE_PARM_DESC(disable_idle_d3,
> >
> >  static struct pci_driver vfio_mdev_pci_driver;
> >
> > -static ssize_t
> > -name_show(struct kobject *kobj, struct device *dev, char *buf) -{
> > -	return sprintf(buf, "%s-type1\n", dev_name(dev));
> > -}
> > -
> > -MDEV_TYPE_ATTR_RO(name);
> > +struct vfio_mdev_pci_device {
> > +	struct vfio_pci_device vdev;
> > +	struct mdev_parent_ops ops;
> > +	struct attribute_group *groups[2];
> > +	struct attribute_group attr;
> > +	atomic_t avail;
> > +};
> >
> >  static ssize_t
> >  available_instances_show(struct kobject *kobj, struct device *dev,
> > char *buf)  {
> > -	return sprintf(buf, "%d\n", 1);
> > +	struct vfio_mdev_pci_device *vmdev;
> > +
> > +	vmdev = pci_get_drvdata(to_pci_dev(dev));
> > +
> > +	return sprintf(buf, "%d\n", atomic_read(&vmdev->avail));
> >  }
> >
> >  MDEV_TYPE_ATTR_RO(available_instances);
> > @@ -90,62 +94,57 @@ static ssize_t device_api_show(struct kobject
> > *kobj, struct device *dev,  MDEV_TYPE_ATTR_RO(device_api);
> >
> >  static struct attribute *vfio_mdev_pci_types_attrs[] = {
> > -	&mdev_type_attr_name.attr,
> >  	&mdev_type_attr_device_api.attr,
> >  	&mdev_type_attr_available_instances.attr,
> >  	NULL,
> >  };
> >
> > -static struct attribute_group vfio_mdev_pci_type_group1 = {
> > -	.name  = "type1",
> > -	.attrs = vfio_mdev_pci_types_attrs,
> > -};
> > -
> > -struct attribute_group *vfio_mdev_pci_type_groups[] = {
> > -	&vfio_mdev_pci_type_group1,
> > -	NULL,
> > -};
> > -
> >  struct vfio_mdev_pci {
> >  	struct vfio_pci_device *vdev;
> >  	struct mdev_device *mdev;
> > -	unsigned long handle;
> >  };
> >
> >  static int vfio_mdev_pci_create(struct kobject *kobj, struct
> > mdev_device *mdev)  {
> >  	struct device *pdev;
> > -	struct vfio_pci_device *vdev;
> > +	struct vfio_mdev_pci_device *vmdev;
> >  	struct vfio_mdev_pci *pmdev;
> >  	int ret;
> >
> >  	pdev = mdev_parent_dev(mdev);
> > -	vdev = dev_get_drvdata(pdev);
> > +	vmdev = dev_get_drvdata(pdev);
> > +
> > +	if (atomic_dec_if_positive(&vmdev->avail) < 0)
> > +		return -ENOSPC;
> > +
> >  	pmdev = kzalloc(sizeof(struct vfio_mdev_pci), GFP_KERNEL);
> > -	if (pmdev == NULL) {
> > -		ret = -EBUSY;
> > -		goto out;
> > -	}
> > +	if (!pmdev)
> > +		return -ENOMEM;
> 
> Needs an atomic_inc(&vmdev->avail) in this error path.  Thanks,

Oops, yes it is.

> 
> Alex

Thanks,
Yi Liu