On Tue, Aug 20, 2019 at 09:08:55PM +0800, zhangfei wrote:
>
>
> On 2019/8/15 下午10:13, Greg Kroah-Hartman wrote:
> > On Wed, Aug 14, 2019 at 05:34:25PM +0800, Zhangfei Gao wrote:
> > > +int uacce_register(struct uacce *uacce)
> > > +{
> > > + int ret;
> > > +
> > > + if (!uacce->pdev) {
> > > + pr_debug("uacce parent device not set\n");
> > > + return -ENODEV;
> > > + }
> > > +
> > > + if (uacce->flags & UACCE_DEV_NOIOMMU) {
> > > + add_taint(TAINT_CRAP, LOCKDEP_STILL_OK);
> > > + dev_warn(uacce->pdev,
> > > + "Register to noiommu mode, which export kernel data to
> > > user space and may vulnerable to attack");
> > > + }
> > THat is odd, why even offer this feature then if it is a major issue?
> UACCE_DEV_NOIOMMU maybe confusing here.
>
> In this mode, app use ioctl to get dma_handle from dma_alloc_coherent.
That's odd, why not use the other default apis to do that?
> It does not matter iommu is enabled or not.
> In case iommu is disabled, it maybe dangerous to kernel, so we added warning
> here, is it required?
You should use the other documentated apis for this, don't create your
own.
thanks,
greg k-h
