Re: [PATCH v3 03/13] iommu/arm-smmu-v3: Drain in-flight fault events on domain detach

On Tue, Sep 08, 2026 at 01:36:43PM -0300, Jason Gunthorpe wrote:

On Fri, Sep 04, 2026 at 03:57:14PM -0700, Nicolin Chen wrote:

quoted

On Fri, Sep 04, 2026 at 11:09:06AM -0300, Jason Gunthorpe wrote:

quoted

On Thu, Sep 03, 2026 at 12:18:33PM -0700, Jonathan Cameron wrote:

quoted

quoted

Also run the drain for every stall-capable master, even when the departing
attachment did not enable IOPF: such a stall event has to be aborted while
it still resolves to the old attach handle, 

That isn't the model for fault handling. The fault is delivered
unpredictably into either old or new domain. It doesn't matter which
one.

Domains have to conclude their fault proceessing before they are
destroyed, and attach to the a non-fault domain has to conclude faults
before completing the attach.

But there is no requirement to deliver faults to any particular thing.

Edited:

Also run the drain for every stall-capable master, even when the departing
attachment did not enable IOPF. An attachment has to conclude its in-flight
faults before the attach completes, as the incoming domain might not handle
a fault at all.

I still don't understand from this why an non-fault capable domain
would need to flush on becoming replaced?

Actually, I missed the part that the iopf core already resolves
this via an IOMMU_PAGE_RESP_INVALID.

So, drain should happen when:
-       if (master->stall_enabled) {
+       if (master_domain->using_iopf && master->stall_enabled) {
 		arm_smmu_wait_for_queue_drained()

And I will drop that paragraph in the commit message.

Thanks!
Nicolin