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SubjectRe: [PATCH v3 05/14] s390: vfio-ap: base implementation of VFIO AP device driver
On Wed, 14 Mar 2018 14:25:45 -0400
Tony Krowiak <akrowiak@linux.vnet.ibm.com> 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@linux.vnet.ibm.com>
> ---
> 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?

> + *
> + * Author(s): Tony Krowiak <akrowiak@linux.vnet.ibm.com>
> + */
> +
> +#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)

> + 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).

> +
> +matrix_alloc_err:
> + root_device_unregister(vfio_ap_root_device);
> +
> +done:
> + return ret;
> +}

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