Re: [PATCH 2/7] Initial skeleton of VFIO support for Device Tree based devices

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

On Mon, 2013-10-28 at 21:29 -0400, Don Dutile wrote:
> On 09/30/2013 11:37 AM, Bhushan Bharat-R65777 wrote:
> >
> >
> >> -----Original Message-----
> >> From: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org [mailto:iommu-
> >> bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org] On Behalf Of Antonios Motakis
> >> Sent: Monday, September 30, 2013 8:59 PM
> >> To: kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org; alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org
> >> Cc: linux-samsung-soc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; kvm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; agraf-l3A5Bk7waGM@public.gmane.org; Yoder
> >> Stuart-B08248; iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org; Antonios Motakis;
> >> tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org
> >> Subject: [PATCH 2/7] Initial skeleton of VFIO support for Device Tree based
> >> devices
> >>
> >> Platform devices in the Linux kernel are usually managed by the DT interface.
> >> This patch forms the base to support these kind of devices with VFIO.
> >>
> >> Signed-off-by: Antonios Motakis<a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>
> >> ---
> >>   drivers/vfio/Kconfig         |  11 +++
> >>   drivers/vfio/Makefile        |   1 +
> >>   drivers/vfio/vfio_platform.c | 187 +++++++++++++++++++++++++++++++++++++++++++
> >>   include/uapi/linux/vfio.h    |   1 +
> >>   4 files changed, 200 insertions(+)
> >>   create mode 100644 drivers/vfio/vfio_platform.c
> >>
> >> diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig index 1f84eda..35254b7
> >> 100644
> >> --- a/drivers/vfio/Kconfig
> >> +++ b/drivers/vfio/Kconfig
> >> @@ -13,4 +13,15 @@ menuconfig VFIO
> >>
> >>   	  If you don't know what to do here, say N.
> >>
> >> +config VFIO_PLATFORM
> >> +	tristate "VFIO support for device tree based platform devices"
> >> +	depends on VFIO&&  EVENTFD&&  OF
> >> +	help
> >> +	  Support for platform devices with VFIO. This is required to make
> >> +	  use of platform devices present on device tree nodes using the VFIO
> >> +	  framework. Devices that are not described in the device tree cannot
> >> +	  be used by this driver.
> >> +
> >> +	  If you don't know what to do here, say N.
> >> +
> >>   source "drivers/vfio/pci/Kconfig"
> >> diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile index
> >> 2398d4a..575c8dd 100644
> >> --- a/drivers/vfio/Makefile
> >> +++ b/drivers/vfio/Makefile
> >> @@ -1,3 +1,4 @@
> >>   obj-$(CONFIG_VFIO) += vfio.o
> >>   obj-$(CONFIG_VFIO_IOMMU_TYPE1) += vfio_iommu_type1.o
> >>   obj-$(CONFIG_VFIO_PCI) += pci/
> >> +obj-$(CONFIG_VFIO_PLATFORM) += vfio_platform.o
> >> diff --git a/drivers/vfio/vfio_platform.c b/drivers/vfio/vfio_platform.c new
> >
> > We can make this parallel to PCI, something like drivers/vfio/platform/platform.c
> >
> pls, no.  'platform' is too generic, and it really means 'arm-dt' ... so can
> move it to the arch/arm space, and have it's kconfig conditional on ARM&&VFIO.
> if kept under drivers/vfio, then use a better directory name that ties it to arm-dt.
> thanks.

The intention is that vfio platform device support is not arm-dt
specific.  This is to be used by both arm and embedded ppc.  The devices
we intend to support with them are known as platform drivers in the
kernel, thus the name.  I suppose the question remains whether the
interface here is really generic for any "platform" device or whether
we're making whether we're making an interface specifically for device
tree platform devices, or if those are one in the same.  In any case,
arm-dt is certainly not the answer.

Alex

> >> file mode 100644 index 0000000..b9686b0
> >> --- /dev/null
> >> +++ b/drivers/vfio/vfio_platform.c
> >> @@ -0,0 +1,187 @@
> >> +/*
> >> + * 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.
> >> + *
> >> + * You should have received a copy of the GNU General Public License
> >> + * along with this program; if not, write to the Free Software
> >> + * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
> >> + */
> >> +
> >> +#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>
> >> +
> >> +#define DRIVER_VERSION  "0.1"
> >> +#define DRIVER_AUTHOR   "Antonios Motakis<a.motakis-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org>"
> >> +#define DRIVER_DESC     "VFIO Device Tree devices - User Level meta-driver"
> >> +
> >> +struct vfio_platform_device {
> >> +	struct platform_device	*pdev;
> >> +};
> >> +
> >> +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;
> >> +}
> >> +
> >> +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 const struct of_device_id vfio_platform_match[] = {
> >> +	/* Before this series can be applied, we shall implement a better
> >> +	 * mechanism to bind the module to any device. For now add the
> >> +	 * compatible property to the dtb of the devices we want to use. */
> >> +	{
> >> +		.compatible = "vfio",
> >> +	},
> >> +	{},
> >> +};
> >> +MODULE_DEVICE_TABLE(of, vfio_platform_match);
> >> +
> >> +static struct platform_driver vfio_platform_driver = {
> >> +	.probe		= vfio_platform_probe,
> >> +	.remove		= vfio_platform_remove,
> >> +	.driver	= {
> >> +		.name	= "vfio-platform",
> >> +		.owner	= THIS_MODULE,
> >> +		.of_match_table = vfio_platform_match,
> >> +	},
> >> +};
> >> +
> >> +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/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index
> >> 284ff24..8d7434d 100644
> >> --- a/include/uapi/linux/vfio.h
> >> +++ b/include/uapi/linux/vfio.h
> >> @@ -147,6 +147,7 @@ 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 */
> >>   };
> >> --
> >> 1.8.1.2
> >>
> >> _______________________________________________
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> >
> >
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