Re: [PATCH] uacce: Add uacce_ctrl misc device

[Greg Kroah-Hartman]

On Thu, Jan 21, 2021 at 05:09:14PM +0800, Zhou Wang wrote:
> When IO page fault happens, DMA performance will be affected. Pin user page
> can avoid IO page fault, this patch introduces a new char device named
> /dev/uacce_ctrl to help to maintain pin/unpin pages. User space can do
> pin/unpin pages by ioctls of an open file of /dev/uacce_ctrl, all pinned
> pages under one file will be unpinned in file release process.
> 
> Signed-off-by: Zhou Wang <wangzhou1@xxxxxxxxxxxxx>
> Signed-off-by: Sihang Chen <chensihang1@xxxxxxxxxxxxx>
> Suggested-by: Barry Song <song.bao.hua@xxxxxxxxxxxxx>
> ---
>  drivers/misc/uacce/uacce.c      | 172 +++++++++++++++++++++++++++++++++++++++-
>  include/uapi/misc/uacce/uacce.h |  16 ++++
>  2 files changed, 187 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/uacce/uacce.c b/drivers/misc/uacce/uacce.c
> index d07af4e..b8ac408 100644
> --- a/drivers/misc/uacce/uacce.c
> +++ b/drivers/misc/uacce/uacce.c
> @@ -2,6 +2,7 @@
>  #include <linux/compat.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/iommu.h>
> +#include <linux/miscdevice.h>
>  #include <linux/module.h>
>  #include <linux/poll.h>
>  #include <linux/slab.h>
> @@ -12,6 +13,16 @@ static dev_t uacce_devt;
>  static DEFINE_MUTEX(uacce_mutex);
>  static DEFINE_XARRAY_ALLOC(uacce_xa);
>  
> +struct uacce_pin_container {
> +	struct xarray array;
> +};
> +
> +struct pin_pages {
> +	unsigned long first;
> +	unsigned long nr_pages;
> +	struct page **pages;
> +};
> +
>  static int uacce_start_queue(struct uacce_queue *q)
>  {
>  	int ret = 0;
> @@ -497,6 +508,152 @@ void uacce_remove(struct uacce_device *uacce)
>  }
>  EXPORT_SYMBOL_GPL(uacce_remove);
>  
> +int uacce_ctrl_open(struct inode *inode, struct file *file)
> +{
> +	struct uacce_pin_container *p;
> +
> +	p = kzalloc(sizeof(*p), GFP_KERNEL);
> +	if (!p)
> +		return -ENOMEM;
> +	file->private_data = p;
> +
> +	xa_init(&p->array);
> +
> +	return 0;
> +}
> +
> +int uacce_ctrl_release(struct inode *inode, struct file *file)
> +{
> +	struct uacce_pin_container *priv = file->private_data;
> +	struct pin_pages *p;
> +	unsigned long idx;
> +
> +	xa_for_each(&priv->array, idx, p) {
> +		unpin_user_pages(p->pages, p->nr_pages);
> +		xa_erase(&priv->array, p->first);
> +		vfree(p->pages);
> +		kfree(p);
> +	}
> +
> +	xa_destroy(&priv->array);
> +	kfree(priv);
> +
> +	return 0;
> +}
> +
> +static int uacce_pin_page(struct uacce_pin_container *priv,
> +			  struct uacce_pin_address *addr)
> +{
> +	unsigned int flags = FOLL_FORCE | FOLL_WRITE;
> +	unsigned long first, last, nr_pages;
> +	struct page **pages;
> +	struct pin_pages *p;
> +	int ret;
> +
> +	first = (addr->addr & PAGE_MASK) >> PAGE_SHIFT;
> +	last = ((addr->addr + addr->size - 1) & PAGE_MASK) >> PAGE_SHIFT;
> +	nr_pages = last - first + 1;
> +
> +	pages = vmalloc(nr_pages * sizeof(struct page *));
> +	if (!pages)
> +		return -ENOMEM;
> +
> +	p = kzalloc(sizeof(*p), GFP_KERNEL);
> +	if (!p) {
> +		ret = -ENOMEM;
> +		goto free;
> +	}
> +
> +	ret = pin_user_pages_fast(addr->addr & PAGE_MASK, nr_pages,
> +				  flags | FOLL_LONGTERM, pages);
> +	if (ret != nr_pages) {
> +		pr_err("uacce: Failed to pin page\n");
> +		goto free_p;
> +	}
> +	p->first = first;
> +	p->nr_pages = nr_pages;
> +	p->pages = pages;
> +
> +	ret = xa_err(xa_store(&priv->array, p->first, p, GFP_KERNEL));
> +	if (ret)
> +		goto unpin_pages;
> +
> +	return 0;
> +
> +unpin_pages:
> +	unpin_user_pages(pages, nr_pages);
> +free_p:
> +	kfree(p);
> +free:
> +	vfree(pages);
> +	return ret;
> +}
> +
> +static int uacce_unpin_page(struct uacce_pin_container *priv,
> +			    struct uacce_pin_address *addr)
> +{
> +	unsigned long first, last, nr_pages;
> +	struct pin_pages *p;
> +
> +	first = (addr->addr & PAGE_MASK) >> PAGE_SHIFT;
> +	last = ((addr->addr + addr->size - 1) & PAGE_MASK) >> PAGE_SHIFT;
> +	nr_pages = last - first + 1;
> +
> +	/* find pin_pages */
> +	p = xa_load(&priv->array, first);
> +	if (!p)
> +		return -ENODEV;
> +
> +	if (p->nr_pages != nr_pages)
> +		return -EINVAL;
> +
> +	/* unpin */
> +	unpin_user_pages(p->pages, p->nr_pages);
> +
> +	/* release resource */
> +	xa_erase(&priv->array, first);
> +	vfree(p->pages);
> +	kfree(p);
> +
> +	return 0;
> +}
> +
> +static long uacce_ctrl_unl_ioctl(struct file *filep, unsigned int cmd,
> +				 unsigned long arg)
> +{
> +	struct uacce_pin_container *p = filep->private_data;
> +	struct uacce_pin_address addr;
> +	int ret;
> +
> +	if (copy_from_user(&addr, (void __user *)arg,
> +			   sizeof(struct uacce_pin_address)))
> +		return -EFAULT;
> +
> +	switch (cmd) {
> +	case UACCE_CMD_PIN:
> +		return uacce_pin_page(p, &addr);
> +
> +	case UACCE_CMD_UNPIN:
> +		return uacce_unpin_page(p, &addr);
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct file_operations uacce_ctrl_fops = {
> +	.owner = THIS_MODULE,
> +	.open = uacce_ctrl_open,
> +	.release = uacce_ctrl_release,
> +	.unlocked_ioctl	= uacce_ctrl_unl_ioctl,
> +};
> +
> +static struct miscdevice uacce_ctrl_miscdev = {
> +	.name = "uacce_ctrl",
> +	.minor = MISC_DYNAMIC_MINOR,
> +	.fops = &uacce_ctrl_fops,
> +};
> +
>  static int __init uacce_init(void)
>  {
>  	int ret;
> @@ -507,13 +664,26 @@ static int __init uacce_init(void)
>  
>  	ret = alloc_chrdev_region(&uacce_devt, 0, MINORMASK, UACCE_NAME);
>  	if (ret)
> -		class_destroy(uacce_class);
> +		goto destroy_class;
> +
> +	ret = misc_register(&uacce_ctrl_miscdev);
> +	if (ret) {
> +		pr_err("uacce: ctrl dev registration failed\n");
> +		goto unregister_cdev;
> +	}
>  
> +	return 0;
> +
> +unregister_cdev:
> +	unregister_chrdev_region(uacce_devt, MINORMASK);
> +destroy_class:
> +	class_destroy(uacce_class);
>  	return ret;
>  }
>  
>  static __exit void uacce_exit(void)
>  {
> +	misc_deregister(&uacce_ctrl_miscdev);
>  	unregister_chrdev_region(uacce_devt, MINORMASK);
>  	class_destroy(uacce_class);
>  }
> diff --git a/include/uapi/misc/uacce/uacce.h b/include/uapi/misc/uacce/uacce.h
> index cc71856..f9e326f 100644
> --- a/include/uapi/misc/uacce/uacce.h
> +++ b/include/uapi/misc/uacce/uacce.h
> @@ -35,4 +35,20 @@ enum uacce_qfrt {
>  	UACCE_QFRT_DUS = 1,
>  };
>  
> +/**
> + * struct uacce_pin_address - Expected pin user space address and size
> + * @addr: Address to pin
> + * @size: Size of pin address
> + */
> +struct uacce_pin_address {
> +	unsigned long addr;
> +	unsigned long size;

These are not valid ioctl structure members for crossing the user/kernel
boundry.  Please make them work properly (i.e. use __u64 and friends).

thanks,

greg k-h