Messages in this thread | | | Date | Mon, 21 Mar 2022 11:42:16 +0000 | From | Jean-Philippe Brucker <> | Subject | Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic |
| |
Hi Kevin,
On Mon, Mar 21, 2022 at 08:09:36AM +0000, Tian, Kevin wrote: > > From: Lu Baolu <baolu.lu@linux.intel.com> > > Sent: Sunday, March 20, 2022 2:40 PM > > > > The existing IOPF handling framework only handles the I/O page faults for > > SVA. Ginven that we are able to link iommu domain with each I/O page fault, > > we can now make the I/O page fault handling framework more general for > > more types of page faults. > > "make ... generic" in subject line is kind of confusing. Reading this patch I > think you really meant changing from per-device fault handling to per-domain > fault handling. This is more accurate in concept since the fault is caused by > the domain page table. 😊
I tend to disagree with that last part. The fault is caused by a specific device accessing shared page tables. We should keep that device information throughout the fault handling, so that we can report it to the driver when things go wrong. A process can have multiple threads bound to different devices, they share the same mm so if the driver wanted to signal a misbehaving thread, similarly to a SEGV on the CPU side, it would need the device information to precisely report it to userspace.
Thanks, Jean
| |