[PATCH v2] ACPI/IORT: Fix PCI ACS enablement

[nwatters@codeaurora.org (Nate Watterson)]

Hi Lorenzo,

On 10/3/2017 8:48 AM, Lorenzo Pieralisi wrote:
> [+Nate]
> 
> Zhou, Nate,
> 
> On Mon, Oct 02, 2017 at 06:28:44PM +0100, Lorenzo Pieralisi wrote:
>> commit f6810c15cf97 ("iommu/arm-smmu: Clean up early-probing
>> workarounds") removed kernel code that was allowing to initialize
>> and probe the SMMU devices early (ie earlier than PCI devices, through
>> linker script callback entries) in the boot process because it was not
>> needed any longer in that the SMMU devices/drivers now support deferred
>> probing.
>>
>> Since the SMMUs probe routines are also in charge of requesting global
>> PCI ACS kernel enablement, commit f6810c15cf97 ("iommu/arm-smmu: Clean
>> up early-probing workarounds") also postponed PCI ACS enablement to
>> SMMUs devices probe time, which is too late given that PCI devices needs
>> to detect if PCI ACS is enabled to init the respective capability
>> through the following call path:
>>
>> pci_device_add()
>>   -> pci_init_capabilities()
>>    -> pci_enable_acs()
>>
>> Add code in the ACPI IORT SMMU platform devices initialization path
>> (that is called before ACPI PCI enumeration) to detect if there
>> exists firmware mappings to map root complexes ids to SMMU ids
>> and if so enable ACS for the system.
>>
>> Fixes: f6810c15cf97 ("iommu/arm-smmu: Clean up early-probing
>> Signed-workarounds")
>> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
>> Cc: Will Deacon <will.deacon@arm.com>
>> Cc: Hanjun Guo <hanjun.guo@linaro.org>
>> Cc: Sudeep Holla <sudeep.holla@arm.com>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Robin Murphy <robin.murphy@arm.com>
>> Cc: Zhou Wang <wangzhou1@hisilicon.com>
>> Cc: Alex Williamson <alex.williamson@redhat.com>
>> ---
>> v1 -> v2:
>>
>> - Reworked ACS enablement logic and based on root complex to SMMU
>>    ids firmware mapping detection
>> - Rebased against v4.14-rc3
>>
>> v1: https://marc.info/?l=linux-acpi&m=150584059818925&w=2
>>
>>   drivers/acpi/arm64/iort.c | 35 +++++++++++++++++++++++++++++++++++
>>   1 file changed, 35 insertions(+)
> 
> I have reworked the enablement logic wrt v1, dou you mind testing it
> please, I would like to get it merged since I have 4.15 patches depending
> on it.

I tested with and without RC->SMMU mappings defined in the IORT and
observed the expected value for pci_acs_enable in both cases.

Tested-by: Nate Watterson <nwatters@codeaurora.org>

Thanks,
Nate

> 
> Thanks,
> Lorenzo
> 
>> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
>> index 9565d57..de56394 100644
>> --- a/drivers/acpi/arm64/iort.c
>> +++ b/drivers/acpi/arm64/iort.c
>> @@ -1178,12 +1178,44 @@ static int __init iort_add_smmu_platform_device(struct acpi_iort_node *node)
>>   	return ret;
>>   }
>>   
>> +static bool __init iort_enable_acs(struct acpi_iort_node *iort_node)
>> +{
>> +	if (iort_node->type == ACPI_IORT_NODE_PCI_ROOT_COMPLEX) {
>> +		struct acpi_iort_node *parent;
>> +		struct acpi_iort_id_mapping *map;
>> +		int i;
>> +
>> +		map = ACPI_ADD_PTR(struct acpi_iort_id_mapping, iort_node,
>> +				   iort_node->mapping_offset);
>> +
>> +		for (i = 0; i < iort_node->mapping_count; i++, map++) {
>> +			if (!map->output_reference)
>> +				continue;
>> +
>> +			parent = ACPI_ADD_PTR(struct acpi_iort_node,
>> +					iort_table,  map->output_reference);
>> +			/*
>> +			 * If we detect a RC->SMMU mapping, make sure
>> +			 * we enable ACS on the system.
>> +			 */
>> +			if ((parent->type == ACPI_IORT_NODE_SMMU) ||
>> +				(parent->type == ACPI_IORT_NODE_SMMU_V3)) {
>> +				pci_request_acs();
>> +				return true;
>> +			}
>> +		}
>> +	}
>> +
>> +	return false;
>> +}
>> +
>>   static void __init iort_init_platform_devices(void)
>>   {
>>   	struct acpi_iort_node *iort_node, *iort_end;
>>   	struct acpi_table_iort *iort;
>>   	struct fwnode_handle *fwnode;
>>   	int i, ret;
>> +	bool acs_enabled = false;
>>   
>>   	/*
>>   	 * iort_table and iort both point to the start of IORT table, but
>> @@ -1203,6 +1235,9 @@ static void __init iort_init_platform_devices(void)
>>   			return;
>>   		}
>>   
>> +		if (!acs_enabled)
>> +			acs_enabled = iort_enable_acs(iort_node);
>> +
>>   		if ((iort_node->type == ACPI_IORT_NODE_SMMU) ||
>>   			(iort_node->type == ACPI_IORT_NODE_SMMU_V3)) {
>>   
>> -- 
>> 2.4.12
>>

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