On Mon, Jan 25, 2021 at 04:34:56PM +0800, Zhou Wang wrote:
> +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);
This needs to copy the RLIMIT_MEMLOCK and can_do_mlock() stuff from
other places, like ib_umem_get
> + ret = xa_err(xa_store(&priv->array, p->first, p, GFP_KERNEL));
And this is really weird, I don't think it makes sense to make handles
for DMA based on the starting VA.
> +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);
And unpinning without guaranteeing there is no ongoing DMA is really
weird
Are you abusing this in conjunction with a SVA scheme just to prevent
page motion? Why wasn't mlock good enough?
Jason
