On Thu, Mar 05, 2026 at 09:33:47PM -0400, Jason Gunthorpe wrote:

On Thu, Mar 05, 2026 at 05:29:22PM -0800, Nicolin Chen wrote:

quoted

But arm_smmu_cmdq_issue_cmdlist() doesn't know when to push another
CMD. In my case where ATC_INV irq occurs, the return value from the
arm_smmu_cmdq_poll_until_sync() in the Step 5 is 0, and prods/cons
are also matched. Actually, at this point that NOP ISR has already
finished.

Yes, you'd need a sneaky way to convay the error from the ISR to the
cmdlist code that didn't harm performance. Maybe we could come up with
something, but if it works replacing the NOP with flush sounds fairly
appealing - though can you do a single WORD edit to the STE that will
block translated requests? Zero EATS?

Yea. I can give that a try.

Also, will the SMMU start spamming with blocked translation events or
something that will need suppression too?

CD.R=0 can suppress fault records, but we would need to override
that in every CD of the device.

Thanks
Nicolin