Re: [PATCH v8 12/12] iommu: Use refcount for fault data access

[Jason Gunthorpe]

On Tue, Dec 12, 2023 at 01:17:47PM +0800, Baolu Lu wrote:
> On 12/11/23 11:24 PM, Jason Gunthorpe wrote:
> > Also iopf_queue_remove_device() is messed up - it returns an error
> > code but nothing ever does anything with it 🙁 Remove functions like
> > this should never fail.
> 
> Yes, agreed.
> 
> > 
> > Removal should be like I explained earlier:
> >   - Disable new PRI reception
> 
> This could be done by
> 
> 	rcu_assign_pointer(param->fault_param, NULL);
> 
> ?

Not without a synchronize_rcu

disable new PRI reception should be done by the driver - it should
turn off PRI generation in the IOMMU HW and flush any HW PRI queues.

> >   - Ack all outstanding PRQ to the device
> 
> All outstanding page requests are responded with
> IOMMU_PAGE_RESP_INVALID, indicating that device should not attempt any
> retry.

Yes

Jason