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:
On Tue, Feb 18, 2025 at 01:18:21PM -0400, Jason Gunthorpe wrote:
On Fri, Jan 24, 2025 at 04:30:42PM -0800, Nicolin Chen wrote:
@@ -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.
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