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

From: [email-masked] (Lorenzo Pieralisi)
Date: Tue, 3 Oct 2017 17:53:01 +0100

On Tue, Oct 03, 2017 at 03:45:38PM +0100, John Garry wrote:
> On 02/10/2017 18:28, 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 <[email-masked]>
> >Cc: Will Deacon <[email-masked]>
> >Cc: Hanjun Guo <[email-masked]>
> >Cc: Sudeep Holla <[email-masked]>
> >Cc: Catalin Marinas <[email-masked]>
> >Cc: Robin Murphy <[email-masked]>
> >Cc: Zhou Wang <[email-masked]>
> >Cc: Alex Williamson <[email-masked]>
> >---
> >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(+)
> >
> >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)) {
> 
> Hi Lorenzo,
> 
> There are a couple of places now which check for any SMMU type.
> Should we have a helper function/macro to condense, like this:
> IORT_TYPE_MASK(type) & IORT_IOMMU_TYPE
> 
> Personal taste, I guess.

I agree, I will add that macro for 4.15, I would like to merge this
as a fix now.

> BTW, unfortunately we can't re-test this week due to Chinese holiday.

Understood, I just would like to get some coverage before asking Will
and Catalin to queue it as a fix.

Cheers,
Lorenzo

> Cheers,
> John
> 
> >+				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)) {
> >
> >
> 
> 
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