[PATCH 3/4] ACPI: IORT: Skip SMMUv3 device ID map for two steps mappings

[Lorenzo Pieralisi]

On Wed, Oct 11, 2017 at 01:26:10PM +0800, Hanjun Guo wrote:
> On 2017/10/10 17:20, Lorenzo Pieralisi wrote:
> > On Tue, Oct 10, 2017 at 02:47:53PM +0800, Hanjun Guo wrote:
> >> Hi Lorenzo,
> >>
> >> Sorry for the late reply, holidays in China for the past week.
> >>
> >> At 2017/9/27 21:54, Lorenzo Pieralisi wrote:
> >>> Hi Hanjun,
> >>>
> >>> On Wed, Sep 27, 2017 at 09:20:14AM +0800, Hanjun Guo wrote:
> >>>> IORT revision C introduced SMMUv3 MSI support which adding a
> >>>> device ID mapping index in SMMUv3 sub table, to get the SMMUv3
> >>>> device ID mapping for the output ID (dev ID for ITS) and the
> >>>> link to which ITS.
> >>>>
> >>>> So if a platform supports SMMUv3 MSI for control interrupt,
> >>>> there will be a additional single map entry under SMMU, this
> >>>> will not introduce any difference for devices just use one
> >>>> step map to get its output ID and parent (ITS or SMMU), such
> >>>> as PCI/NC/PMCG ---> ITS or PCI/NC ---> SMMU, but we need to
> >>>> do the special handling for two steps map case such as
> >>>> PCI/NC--->SMMUv3--->ITS.
> >>>>
> >>>> Take a PCI hostbridge for example,
> >>>>
> >>>> |----------------------|
> >>>> |  Root Complex Node   |
> >>>> |----------------------|
> >>>> |    map entry[x]      |
> >>>> |----------------------|
> >>>> |       id value       |
> >>>> | output_reference     |
> >>>> |---|------------------|
> >>>>      |
> >>>>      |   |----------------------|
> >>>>      |-->|        SMMUv3        |
> >>>>          |----------------------|
> >>>>          |     SMMU dev ID      |
> >>>>          |     mapping index 0  |
> >>>>          |----------------------|
> >>>>          |      map entry[0]    |
> >>>>          |----------------------|
> >>>>          |       id value       |
> >>>>          | output_reference-----------> ITS 1 (SMMU MSI domain)
> >>>>          |----------------------|
> >>>>          |      map entry[1]    |
> >>>>          |----------------------|
> >>>>          |       id value       |
> >>>>          | output_reference-----------> ITS 2 (PCI MSI domain)
> >>>>          |----------------------|
> >>>>
> >>>> When the SMMU dev ID mapping index is 0, there is entry[0]
> >>>> to map to a ITS, we need to skip that map entry for PCI
> >>>> or NC (named component), or we may get the wrong ITS parent.
> >>> Is this actually true ? I think that currently we would simply skip
> >>> the entry and print an error log but we can't get a wrong ITS parent.
> >> So the only valid single mapping under type SMMUv3 is SMMUv3's dev id
> >> mapping, we need to fix the IORT spec as well.
> >>
> >>> I am rewriting this commit (I will probably split it), it is doing the
> >>> right thing but the commit log is stale (probably caused by code
> >>> reshuffling).
> >> Do I need to resend another version, or you can help to update it?
> >> please let me know.
> > I reworked the patches, you can repost/retest them I made them available
> > in the branch below, we will have to add a guard around ACPICA smmu
> > struct (unfortunately I think we will have to use the ACPICA version as
> > a guard) or I can ask Rafael to pull the series if ACPICA goes via ACPI
> > tree (and your patch made it into the release - I will check ACPICA
> > upstream).
> 
> Bob already merged my pull request yesterday, I think it will be ready for
> acpica release for this month.

That's good, mind updating the patch series with an ACPICA guard in IORT
code in preparation for the pull request ?

> > git://git.kernel.org/pub/scm/linux/kernel/git/lpieralisi/linux.git iort/smmu-msi-for-4.15
> >
> 
> Thanks! I will retest then repost.

Thank you,
Lorenzo