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

[Lorenzo Pieralisi]

On Thu, Oct 12, 2017 at 03:30:10PM +0800, Hanjun Guo wrote:
> On 2017/10/11 18:24, Lorenzo Pieralisi wrote:
> > 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 ?
> 
> Do you mean drop the acpica patch in this patch set and adding the code below?

Yes unless we find a "smarter" way of handling the dependency.

Thanks,
Lorenzo

> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index 37a1b9f..a883bec 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -366,6 +366,7 @@ static struct acpi_iort_node *iort_node_get_id(struct acpi_iort_node *node,
>         return NULL;
>  }
>  
> +#if (ACPI_CA_VERSION > 0x20170929)
>  static int iort_get_id_mapping_index(struct acpi_iort_node *node)
>  {
>         struct acpi_iort_smmu_v3 *smmu;
> @@ -399,6 +400,12 @@ static int iort_get_id_mapping_index(struct acpi_iort_node *node)
>                 return -EINVAL;
>         }
>  }
> +#else
> +static int iort_get_id_mapping_index(struct acpi_iort_node *node)
> +{
> + return -EINVAL;
> +}
> +#endif
>  
> Thanks
> Hanjun
>