On Tue, Feb 18, 2025 at 02:50:46PM -0400, Jason Gunthorpe wrote:

On Tue, Feb 18, 2025 at 10:28:04AM -0800, Nicolin Chen wrote:

quoted

On Tue, Feb 18, 2025 at 01:18:21PM -0400, Jason Gunthorpe wrote:

quoted

On Fri, Jan 24, 2025 at 04:30:42PM -0800, Nicolin Chen wrote:

quoted

@@ -1831,31 +1831,30 @@ static int arm_smmu_handle_event(struct arm_smmu_device *smmu,
 		return -EOPNOTSUPP;
 	}

There is still the filter at the top:

	switch (event->id) {
	case EVT_ID_TRANSLATION_FAULT:
	case EVT_ID_ADDR_SIZE_FAULT:
	case EVT_ID_ACCESS_FAULT:
	case EVT_ID_PERMISSION_FAULT:
		break;
	default:
		return -EOPNOTSUPP;
	}

Is that right here or should more event types be forwarded to the
guest?

That doesn't seem to be right. Something like EVT_ID_BAD_CD_CONFIG
should be forwarded too. I will go through the list.

I think the above should decode into a 'faultable' path because they
all decode to something with an IOVA

The rest should decode to things that include a SID and the SID decode
should always be forwarded to the VM. Maybe there are small
exclusions, but generally that is how I would see it..

Ack. SMMU spec defines three type:
"Three categories of events might be recorded into the Event queue:
 • Configuration errors.
 • Faults from the translation process.
 • Miscellaneous."

The driver cares the first two only, as you remarked here.

quoted

quoted

This already holds the streams_mutex across all of this, do you think
we should get rid of the vmaster_rwsem and hold the streams_mutex on
write instead?

They are per master v.s. per smmu. The latter one would make master
commits/attaches exclusive, which feels unnecessary to me, although
it would make the code here slightly cleaner..

I'd pay the cost on the attach side to have a single lock on the fault
side..

OK. Maybe a small patch to turn the streams_mutex to streams_rwsem?

Thanks
Nicolin