Re: [RFC PATCH v5 05/11] VFIO_PLATFORM: Initial skeleton of VFIO support for platform devices

[Alex Williamson <alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>]

On Mon, 2014-04-28 at 17:52 +0200, Antonios Motakis wrote:
> This patch forms the skeleton for platform devices support with VFIO.
> 
> Signed-off-by: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> ---
>  drivers/vfio/Kconfig                          |   1 +
>  drivers/vfio/Makefile                         |   1 +
>  drivers/vfio/platform/Kconfig                 |   9 ++
>  drivers/vfio/platform/Makefile                |   4 +
>  drivers/vfio/platform/vfio_platform.c         | 172 ++++++++++++++++++++++++++
>  drivers/vfio/platform/vfio_platform_private.h |  22 ++++
>  include/uapi/linux/vfio.h                     |   1 +
>  7 files changed, 210 insertions(+)
>  create mode 100644 drivers/vfio/platform/Kconfig
>  create mode 100644 drivers/vfio/platform/Makefile
>  create mode 100644 drivers/vfio/platform/vfio_platform.c
>  create mode 100644 drivers/vfio/platform/vfio_platform_private.h
> 
> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
> index 3a598ed..a484d72 100644
> --- a/drivers/vfio/Kconfig
> +++ b/drivers/vfio/Kconfig
> @@ -21,3 +21,4 @@ menuconfig VFIO
>  	  If you don't know what to do here, say N.
>  
>  source "drivers/vfio/pci/Kconfig"
> +source "drivers/vfio/platform/Kconfig"
> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
> index 72bfabc..b5e4a33 100644
> --- a/drivers/vfio/Makefile
> +++ b/drivers/vfio/Makefile
> @@ -2,3 +2,4 @@ obj-$(CONFIG_VFIO) += vfio.o
>  obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
>  obj-$(CONFIG_VFIO_IOMMU_SPAPR_TCE) += vfio_iommu_spapr_tce.o
>  obj-$(CONFIG_VFIO_PCI) += pci/
> +obj-$(CONFIG_VFIO_PLATFORM) += platform/
> diff --git a/drivers/vfio/platform/Kconfig b/drivers/vfio/platform/Kconfig
> new file mode 100644
> index 0000000..42b0022
> --- /dev/null
> +++ b/drivers/vfio/platform/Kconfig
> @@ -0,0 +1,9 @@
> +config VFIO_PLATFORM
> +	tristate "VFIO support for platform devices"
> +	depends on VFIO && EVENTFD

VFIO_PCI also depends on PCI, is there no CONFIG_PLATFORM?  What benefit
would I get from this if I enable it on my x86 box?

> +	help
> +	  Support for platform devices with VFIO. This is required to make
> +	  use of platform devices present on the system using the VFIO
> +	  framework.
> +
> +	  If you don't know what to do here, say N.
> diff --git a/drivers/vfio/platform/Makefile b/drivers/vfio/platform/Makefile
> new file mode 100644
> index 0000000..df3a014
> --- /dev/null
> +++ b/drivers/vfio/platform/Makefile
> @@ -0,0 +1,4 @@
> +
> +vfio-platform-y := vfio_platform.o
> +
> +obj-$(CONFIG_VFIO_PLATFORM) += vfio-platform.o
> diff --git a/drivers/vfio/platform/vfio_platform.c b/drivers/vfio/platform/vfio_platform.c
> new file mode 100644
> index 0000000..1661746
> --- /dev/null
> +++ b/drivers/vfio/platform/vfio_platform.c
> @@ -0,0 +1,172 @@
> +/*
> + * Copyright (C) 2013 - Virtual Open Systems
> + * Author: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/device.h>
> +#include <linux/eventfd.h>
> +#include <linux/interrupt.h>
> +#include <linux/iommu.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/notifier.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>
> +#include <linux/uaccess.h>
> +#include <linux/vfio.h>
> +#include <linux/io.h>
> +#include <linux/platform_device.h>
> +#include <linux/irq.h>
> +
> +#include "vfio_platform_private.h"
> +
> +#define DRIVER_VERSION  "0.5"
> +#define DRIVER_AUTHOR   "Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>"
> +#define DRIVER_DESC     "VFIO for platform devices - User Level meta-driver"
> +
> +static void vfio_platform_release(void *device_data)
> +{
> +	module_put(THIS_MODULE);
> +}
> +
> +static int vfio_platform_open(void *device_data)
> +{
> +	if (!try_module_get(THIS_MODULE))
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static long vfio_platform_ioctl(void *device_data,
> +			   unsigned int cmd, unsigned long arg)
> +{
> +	struct vfio_platform_device *vdev = device_data;
> +	unsigned long minsz;
> +
> +	if (cmd == VFIO_DEVICE_GET_INFO) {
> +		struct vfio_device_info info;
> +
> +		minsz = offsetofend(struct vfio_device_info, num_irqs);
> +
> +		if (copy_from_user(&info, (void __user *)arg, minsz))
> +			return -EFAULT;
> +
> +		if (info.argsz < minsz)
> +			return -EINVAL;
> +
> +		info.flags = VFIO_DEVICE_FLAGS_PLATFORM;
> +		info.num_regions = 0;
> +		info.num_irqs = 0;
> +
> +		return copy_to_user((void __user *)arg, &info, minsz);
> +
> +	} else if (cmd == VFIO_DEVICE_GET_REGION_INFO)
> +		return -EINVAL;
> +
> +	else if (cmd == VFIO_DEVICE_GET_IRQ_INFO)
> +		return -EINVAL;
> +
> +	else if (cmd == VFIO_DEVICE_SET_IRQS)
> +		return -EINVAL;
> +
> +	else if (cmd == VFIO_DEVICE_RESET)
> +		return -EINVAL;
> +
> +	return -ENOTTY;
> +}
> +
> +static ssize_t vfio_platform_read(void *device_data, char __user *buf,
> +			     size_t count, loff_t *ppos)
> +{
> +	return 0;
> +}
> +
> +static ssize_t vfio_platform_write(void *device_data, const char __user *buf,
> +			      size_t count, loff_t *ppos)
> +{
> +	return 0;
> +}

I know these are just stubs, but I suspect they should probably return
error.  Thanks,

Alex

> +
> +static int vfio_platform_mmap(void *device_data, struct vm_area_struct *vma)
> +{
> +	return -EINVAL;
> +}
> +
> +static const struct vfio_device_ops vfio_platform_ops = {
> +	.name		= "vfio-platform",
> +	.open		= vfio_platform_open,
> +	.release	= vfio_platform_release,
> +	.ioctl		= vfio_platform_ioctl,
> +	.read		= vfio_platform_read,
> +	.write		= vfio_platform_write,
> +	.mmap		= vfio_platform_mmap,
> +};
> +
> +static int vfio_platform_probe(struct platform_device *pdev)
> +{
> +	struct vfio_platform_device *vdev;
> +	struct iommu_group *group;
> +	int ret;
> +
> +	group = iommu_group_get(&pdev->dev);
> +	if (!group) {
> +		pr_err("VFIO: No IOMMU group for device %s\n", pdev->name);
> +		return -EINVAL;
> +	}
> +
> +	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
> +	if (!vdev) {
> +		iommu_group_put(group);
> +		return -ENOMEM;
> +	}
> +
> +	vdev->pdev = pdev;
> +
> +	ret = vfio_add_group_dev(&pdev->dev, &vfio_platform_ops, vdev);
> +	if (ret) {
> +		iommu_group_put(group);
> +		kfree(vdev);
> +	}
> +
> +	return ret;
> +}
> +
> +static int vfio_platform_remove(struct platform_device *pdev)
> +{
> +	struct vfio_platform_device *vdev;
> +
> +	vdev = vfio_del_group_dev(&pdev->dev);
> +	if (!vdev)
> +		return -EINVAL;
> +
> +	iommu_group_put(pdev->dev.iommu_group);
> +	kfree(vdev);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver vfio_platform_driver = {
> +	.probe		= vfio_platform_probe,
> +	.remove		= vfio_platform_remove,
> +	.driver	= {
> +		.name	= "vfio-platform",
> +		.owner	= THIS_MODULE,
> +	},
> +};
> +
> +module_platform_driver(vfio_platform_driver);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> diff --git a/drivers/vfio/platform/vfio_platform_private.h b/drivers/vfio/platform/vfio_platform_private.h
> new file mode 100644
> index 0000000..4ae88f8
> --- /dev/null
> +++ b/drivers/vfio/platform/vfio_platform_private.h
> @@ -0,0 +1,22 @@
> +/*
> + * Copyright (C) 2013 - Virtual Open Systems
> + * Author: Antonios Motakis <a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License, version 2, as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef VFIO_PLATFORM_PRIVATE_H
> +#define VFIO_PLATFORM_PRIVATE_H
> +
> +struct vfio_platform_device {
> +	struct platform_device		*pdev;
> +};
> +
> +#endif /* VFIO_PLATFORM_PRIVATE_H */
> diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
> index 0847b29..b1a8de8 100644
> --- a/include/uapi/linux/vfio.h
> +++ b/include/uapi/linux/vfio.h
> @@ -155,6 +155,7 @@ struct vfio_device_info {
>  	__u32	flags;
>  #define VFIO_DEVICE_FLAGS_RESET	(1 << 0)	/* Device supports reset */
>  #define VFIO_DEVICE_FLAGS_PCI	(1 << 1)	/* vfio-pci device */
> +#define VFIO_DEVICE_FLAGS_PLATFORM (1 << 2)	/* vfio-platform device */
>  	__u32	num_regions;	/* Max region index + 1 */
>  	__u32	num_irqs;	/* Max IRQ index + 1 */
>  };