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;
+};
+
+/* UACCE_CMD_PIN: Pin a range of memory */
+#define UACCE_CMD_PIN _IOW('W', 2, struct uacce_pin_address)
+
+/* UACCE_CMD_UNPIN: Unpin a range of memory */
+#define UACCE_CMD_UNPIN _IOW('W', 3, struct uacce_pin_address)
+
#endif
--
2.8.1
