Re: [PATCH v11 04/26] s390: vfio-ap: base implementation of VFIO AP device driver

[David Hildenbrand <david@redhat.com>]

On 26/09/2018 01:16, Tony Krowiak wrote:
> From: Tony Krowiak <akrowiak@linux.ibm.com>
> 
> 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 zcrypt
>    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. This limitation was imposed
>   due to:
> 
>   1. A desire to keep the code as simple as possible;
> 
>   2. Some older models are no longer supported by the kernel
>      and others are getting close to end of service.
> 
>   3. A lack of older systems on which to test older 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 matrix device, /sys/devices/vfio_ap/matrix,
>   to serve as the parent of the mediated devices created, one
>   for each guest, and to hold the APQNs of the AP devices bound to
>   the VFIO AP device driver.
> 
> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
> Tested-by: Michael Mueller <mimu@linux.ibm.com>
> Tested-by: Farhan Ali <alifm@linux.ibm.com>
> ---
>  MAINTAINERS                           |  10 ++
>  arch/s390/Kconfig                     |  11 ++
>  drivers/iommu/Kconfig                 |   8 ++
>  drivers/s390/crypto/Makefile          |   4 +
>  drivers/s390/crypto/vfio_ap_drv.c     | 138 ++++++++++++++++++++++++++
>  drivers/s390/crypto/vfio_ap_private.h |  34 +++++++
>  6 files changed, 205 insertions(+)
>  create mode 100644 drivers/s390/crypto/vfio_ap_drv.c
>  create mode 100644 drivers/s390/crypto/vfio_ap_private.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e993064637ca..45cd096c0600 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12668,6 +12668,16 @@ W:	http://www.ibm.com/developerworks/linux/linux390/
>  S:	Supported
>  F:	drivers/s390/crypto/
>  
> +S390 VFIO AP DRIVER
> +M:	Tony Krowiak <akrowiak@linux.ibm.com>
> +M:	Pierre Morel <pmorel@linux.ibm.com>
> +M:	Halil Pasic <pasic@linux.ibm.com>
> +L:	linux-s390@vger.kernel.org
> +W:	http://www.ibm.com/developerworks/linux/linux390/
> +S:	Supported
> +F:	drivers/s390/crypto/vfio_ap_drv.c
> +F:	drivers/s390/crypto/vfio_ap_private.h
> +
>  S390 ZFCP DRIVER
>  M:	Steffen Maier <maier@linux.ibm.com>
>  M:	Benjamin Block <bblock@linux.ibm.com>
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 9a9c7a6fe925..8cc8f25d9576 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -773,6 +773,17 @@ config VFIO_CCW
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called vfio_ccw.
>  
> +config VFIO_AP
> +	def_tristate n
> +	prompt "VFIO support for AP devices"
> +	depends on S390_AP_IOMMU && VFIO_MDEV_DEVICE && KVM
> +	help
> +		This driver grants access to Adjunct Processor (AP) devices
> +		via the VFIO mediated device interface.
> +
> +		To compile this driver as a module, choose M here: the module
> +		will be called vfio_ap.
> +
>  endmenu
>  
>  menu "Dump support"
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index c60395b7470f..83e6d993fca5 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -372,6 +372,14 @@ config S390_CCW_IOMMU
>  	  Enables bits of IOMMU API required by VFIO. The iommu_ops
>  	  is not implemented as it is not necessary for VFIO.
>  
> +config S390_AP_IOMMU
> +	bool "S390 AP IOMMU Support"
> +	depends on S390 && ZCRYPT
> +	select IOMMU_API
> +	help
> +	  Enables bits of IOMMU API required by VFIO. The iommu_ops
> +	  is not implemented as it is not necessary for VFIO.
> +
>  config MTK_IOMMU
>  	bool "MTK IOMMU Support"
>  	depends on ARM || ARM64
> diff --git a/drivers/s390/crypto/Makefile b/drivers/s390/crypto/Makefile
> index b59af548ed1c..48e466eb19cf 100644
> --- a/drivers/s390/crypto/Makefile
> +++ b/drivers/s390/crypto/Makefile
> @@ -15,3 +15,7 @@ obj-$(CONFIG_ZCRYPT) += zcrypt_pcixcc.o zcrypt_cex2a.o zcrypt_cex4.o
>  # pkey kernel module
>  pkey-objs := pkey_api.o
>  obj-$(CONFIG_PKEY) += pkey.o
> +
> +# adjunct processor matrix
> +vfio_ap-objs := vfio_ap_drv.o
> +obj-$(CONFIG_VFIO_AP) += vfio_ap.o
> diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
> new file mode 100644
> index 000000000000..ea2ae03c896e
> --- /dev/null
> +++ b/drivers/s390/crypto/vfio_ap_drv.c
> @@ -0,0 +1,138 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * VFIO based AP device driver
> + *
> + * Copyright IBM Corp. 2018
> + *
> + * Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/slab.h>
> +#include <linux/string.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. 2018");
> +MODULE_LICENSE("GPL v2");
> +
> +static struct ap_driver vfio_ap_drv;
> +
> +static struct device_type vfio_ap_dev_type = {
> +	.name = VFIO_AP_DEV_TYPE_NAME,
> +};
> +
> +struct ap_matrix_dev *matrix_dev;
> +
> +/* 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_queue_dev_remove(struct ap_device *apdev)
> +{
> +	/* Nothing to do yet */
> +}
> +
> +static void vfio_ap_matrix_dev_release(struct device *dev)
> +{
> +	struct ap_matrix_dev *matrix_dev = dev_get_drvdata(dev);
> +
> +	kfree(matrix_dev);
> +}
> +
> +static int vfio_ap_matrix_dev_create(void)
> +{
> +	int ret;
> +	struct device *root_device;
> +
> +	root_device = root_device_register(VFIO_AP_ROOT_NAME);
> +	if (IS_ERR(root_device))
> +		return PTR_ERR(root_device);
> +
> +	matrix_dev = kzalloc(sizeof(*matrix_dev), GFP_KERNEL);
> +	if (!matrix_dev) {
> +		ret = -ENOMEM;
> +		goto matrix_alloc_err;
> +	}
> +
> +	matrix_dev->device.type = &vfio_ap_dev_type;
> +	dev_set_name(&matrix_dev->device, "%s", VFIO_AP_DEV_NAME);
> +	matrix_dev->device.parent = root_device;
> +	matrix_dev->device.release = vfio_ap_matrix_dev_release;
> +	matrix_dev->device.driver = &vfio_ap_drv.driver;
> +
> +	ret = device_register(&matrix_dev->device);
> +	if (ret)
> +		goto matrix_reg_err;
> +
> +	return 0;
> +
> +matrix_reg_err:
> +	put_device(&matrix_dev->device);
> +matrix_alloc_err:
> +	root_device_unregister(root_device);
> +
> +	return ret;
> +}
> +
> +static void vfio_ap_matrix_dev_destroy(void)
> +{
> +	device_unregister(&matrix_dev->device);
> +	root_device_unregister(matrix_dev->device.parent);
> +}
> +
> +int __init vfio_ap_init(void)
> +{
> +	int ret;
> +
> +	/* If there are no AP instructions, there is nothing to pass through. */
> +	if (!ap_instructions_available())
> +		return -ENODEV;
> +
> +	ret = vfio_ap_matrix_dev_create();
> +	if (ret)
> +		return ret;
> +
> +	memset(&vfio_ap_drv, 0, sizeof(vfio_ap_drv));
> +	vfio_ap_drv.probe = vfio_ap_queue_dev_probe;
> +	vfio_ap_drv.remove = vfio_ap_queue_dev_remove;
> +	vfio_ap_drv.ids = ap_queue_ids;
> +
> +	ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
> +	if (ret) {
> +		vfio_ap_matrix_dev_destroy();
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +void __exit vfio_ap_exit(void)
> +{
> +	ap_driver_unregister(&vfio_ap_drv);
> +	vfio_ap_matrix_dev_destroy();
> +}
> +
> +module_init(vfio_ap_init);
> +module_exit(vfio_ap_exit);
> diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
> new file mode 100644
> index 000000000000..6141420c8bb0
> --- /dev/null
> +++ b/drivers/s390/crypto/vfio_ap_private.h
> @@ -0,0 +1,34 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Private data and functions for adjunct processor VFIO matrix driver.
> + *
> + * Author(s): Tony Krowiak <akrowiak@linux.ibm.com>
> + *
> + * Copyright IBM Corp. 2018
> + */
> +
> +#ifndef _VFIO_AP_PRIVATE_H_
> +#define _VFIO_AP_PRIVATE_H_
> +
> +#include <linux/types.h>
> +#include <linux/device.h>
> +#include <linux/mdev.h>
> +#include <linux/delay.h>
> +#include <linux/mutex.h>
> +
> +#include "ap_bus.h"
> +
> +#define VFIO_AP_MODULE_NAME "vfio_ap"
> +#define VFIO_AP_DRV_NAME "vfio_ap"
> +
> +/**
> + * ap_matrix_dev - the AP matrix device structure
> + * @device:	generic device structure associated with the AP matrix device
> + */
> +struct ap_matrix_dev {
> +	struct device device;
> +};
> +
> +extern struct ap_matrix_dev *matrix_dev;
> +
> +#endif /* _VFIO_AP_PRIVATE_H_ */
> 


From what I can tell

Acked-by: David Hildenbrand <david@redhat.com>

-- 

Thanks,

David / dhildenb