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..
> > 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..
Jason
