Re: [PATCH v3 05/14] s390: vfio-ap: base implementation of VFIO AP device driver

[Tony Krowiak]

On 04/03/2018 06:57 AM, Cornelia Huck wrote:
> On Wed, 14 Mar 2018 14:25:45 -0400
> Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx> wrote:
>
> > Introduces a new AP device driver. This device driver
> > is built on the VFIO mediated device framework. The framework
> > provides sysfs interfaces that facilitate passthrough
> > access by guests to devices installed on the linux host.
> >
> > The VFIO AP device driver will serve two purposes:
> >
> > 1. Provide the interfaces to reserve AP devices for exclusive
> >     use by KVM guests. This is accomplished by unbinding the
> >     devices to be reserved for guest usage from the default AP
> >     device driver and binding them to the VFIO AP device driver.
> >
> > 2. Implements the functions, callbacks and sysfs attribute
> >     interfaces required to create one or more VFIO mediated
> >     devices each of which will be used to configure the AP
> >     matrix for a guest and serve as a file descriptor
> >     for facilitating communication between QEMU and the
> >     VFIO AP device driver.
> >
> > When the VFIO AP device driver is initialized:
> >
> > * It registers with the AP bus for control of type 10 (CEX4
> >    and newer) AP queue devices. The probe and remove callbacks
> >    will be provided to support the binding/unbinding of
> >    AP queue devices to/from the VFIO AP device driver.
> >
> > * Creates a /sys/devices/vfio-ap/matrix device to hold
> >    the APQNs of the AP devices bound to the VFIO
> >    AP device driver and serves as the parent of the
> >    mediated devices created for each guest.
> >
> > Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
> > ---
> >   MAINTAINERS                           |    2 +
> >   arch/s390/Kconfig                     |   11 +++
> >   drivers/s390/crypto/Makefile          |    4 +
> >   drivers/s390/crypto/vfio_ap_drv.c     |  135 +++++++++++++++++++++++++++++++++
> >   drivers/s390/crypto/vfio_ap_private.h |   22 ++++++
> >   include/uapi/linux/vfio.h             |    2 +
> >   6 files changed, 176 insertions(+), 0 deletions(-)
> >   create mode 100644 drivers/s390/crypto/vfio_ap_drv.c
> >   create mode 100644 drivers/s390/crypto/vfio_ap_private.h
> >
> > diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> > new file mode 100644
> > index 0000000..459e595
> > --- /dev/null
> > +++ b/drivers/s390/crypto/vfio_ap_drv.c
> > @@ -0,0 +1,135 @@
> > +/*
> > + * VFIO based AP device driver
> > + *
> > + * Copyright IBM Corp. 2017
> Update to 2018?
Okay, will do.
> > + *
> > + * Author(s): Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
> > + */
> > +
> > +#include <linux/module.h>
> > +#include <linux/mod_devicetable.h>
> > +#include <linux/slab.h>
> > +
> > +#include "vfio_ap_private.h"
> > +
> > +#define VFIO_AP_ROOT_NAME "vfio_ap"
> > +#define VFIO_AP_DEV_TYPE_NAME "ap_matrix"
> > +#define VFIO_AP_DEV_NAME "matrix"
> > +
> > +MODULE_AUTHOR("IBM Corporation");
> > +MODULE_DESCRIPTION("VFIO AP device driver, Copyright IBM Corp. 2017");
> > +MODULE_LICENSE("GPL v2");
> > +
> > +static struct device *vfio_ap_root_device;
> > +
> > +static struct ap_driver vfio_ap_drv;
> > +
> > +static struct ap_matrix *ap_matrix;
> > +
> > +static struct device_type vfio_ap_dev_type = {
> > +	.name = VFIO_AP_DEV_TYPE_NAME,
> > +};
> > +
> > +/* Only type 10 adapters (CEX4 and later) are supported
> > + * by the AP matrix device driver
> > + */
> > +static struct ap_device_id ap_queue_ids[] = {
> > +	{ .dev_type = AP_DEVICE_TYPE_CEX4,
> > +	  .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
> > +	{ .dev_type = AP_DEVICE_TYPE_CEX5,
> > +	  .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
> > +	{ .dev_type = AP_DEVICE_TYPE_CEX6,
> > +	  .match_flags = AP_DEVICE_ID_MATCH_QUEUE_TYPE },
> > +	{ /* end of sibling */ },
> > +};
> > +
> > +MODULE_DEVICE_TABLE(vfio_ap, ap_queue_ids);
> > +
> > +static int vfio_ap_queue_dev_probe(struct ap_device *apdev)
> > +{
> > +	return 0;
> > +}
> > +
> > +static void vfio_ap_matrix_dev_release(struct device *dev)
> > +{
> > +	struct ap_matrix *ap_matrix = dev_get_drvdata(dev);
> > +
> > +	kfree(ap_matrix);
> > +}
> > +
> > +static int vfio_ap_matrix_dev_create(void)
> > +{
> > +	int ret;
> > +
> > +	vfio_ap_root_device = root_device_register(VFIO_AP_ROOT_NAME);
> > +
> > +	ret = IS_ERR(vfio_ap_root_device);
> > +	if (ret) {
> Minor nit: I'd contract that to
>
> if (IS_ERR(vfio_ap_root_device)) {
>
> (you're writing ret in any case)
Okay, will do.
> > +		ret = PTR_ERR(vfio_ap_root_device);
> > +		goto done;
> > +	}
> > +
> > +	ap_matrix = kzalloc(sizeof(*ap_matrix), GFP_KERNEL);
> > +	if (!ap_matrix) {
> > +		ret = -ENOMEM;
> > +		goto matrix_alloc_err;
> > +	}
> > +
> > +	ap_matrix->device.type = &vfio_ap_dev_type;
> > +	dev_set_name(&ap_matrix->device, "%s", VFIO_AP_DEV_NAME);
> > +	ap_matrix->device.parent = vfio_ap_root_device;
> > +	ap_matrix->device.release = vfio_ap_matrix_dev_release;
> > +	ap_matrix->device.driver = &vfio_ap_drv.driver;
> > +
> > +	ret = device_register(&ap_matrix->device);
> > +	if (ret)
> > +		goto matrix_reg_err;
> > +
> > +	goto done;
> > +
> > +matrix_reg_err:
> > +	put_device(&ap_matrix->device);
> > +	kfree(ap_matrix);
> The kfree() is wrong: If you called device_register for the embedded
> struct device, this needs to be handled via the ->release callback
> exclusively (IOW, the put_device() is enough and the kfree needs to go).
Ah yes, I see that. I will fix it.
> > +
> > +matrix_alloc_err:
> > +	root_device_unregister(vfio_ap_root_device);
> > +
> > +done:
> > +	return ret;
> > +}