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

[Hanjun Guo <guohanjun@huawei.com>]

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?

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