Re: [PATCH RFC 10/11] iommu: Make IOPF handling framework generic

Jason Gunthorpe
2022-03-22T12:15:37Z

On Tue, Mar 22, 2022 at 01:03:14PM +0800, Lu Baolu wrote:
> On 2022/3/21 20:43, Jason Gunthorpe wrote:
> > On Mon, Mar 21, 2022 at 11:42:16AM +0000, Jean-Philippe Brucker wrote:
> >
> > > 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.
> > SVA faults should never be reported to drivers??
> >
>
> When things go wrong, the corresponding response code will be responded
> to the device through iommu_page_response(). The hardware should then
> report the failure to the device driver and the device driver will
> handle it in the device-specific way. There's no need to propagate the
> I/O page faults to the device driver in any case. Do I understand it
> right?

Something like that, I would expect fault failure to be similar to
accessing somethiing that is not in the iommu map. An Error TLP like
thing toward the device and whatever normal device-specific error
propagation happens.

SVA shouldn't require any special support in the using driver beyond
turing on PRI/ATS

Jason