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[PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU

fangyu.yu@linux.alibaba.com posted 1 patch 3 weeks, 2 days ago
There is a newer version of this series
drivers/acpi/riscv/rimt.c | 56 +++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
[PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
Posted by fangyu.yu@linux.alibaba.com 3 weeks, 2 days ago 
From: Fangyu Yu <fangyu.yu@linux.alibaba.com>

Mirror the ACPI IORT solution used on arm64 (see iort_enable_acs())
by scanning the RIMT table for PCIe root complex nodes during
riscv_acpi_rimt_init(), which runs before ACPI PCI enumeration. If a
root complex node's ID mapping points at an IOMMU node, call
pci_request_acs() immediately, so pci_acs_enable is already set by
the time any PCI device is scanned and pci_enable_acs() runs.

Only one call to pci_request_acs() is needed regardless of how many
root complexes are found, so track that with a static acs_enabled
flag, same as iort_enable_acs() does.

Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
---
 drivers/acpi/riscv/rimt.c | 56 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/acpi/riscv/rimt.c b/drivers/acpi/riscv/rimt.c
index e4538fa6c2c8..f22e28c8211e 100644
--- a/drivers/acpi/riscv/rimt.c
+++ b/drivers/acpi/riscv/rimt.c
@@ -179,6 +179,42 @@ static struct acpi_rimt_node *rimt_scan_node(enum acpi_rimt_node_type type,
 	return NULL;
 }
 
+#ifdef CONFIG_PCI
+static void __init rimt_enable_acs(struct acpi_rimt_node *rimt_node)
+{
+	static bool acs_enabled __initdata;
+	struct acpi_rimt_pcie_rc *pci_rc;
+	struct acpi_rimt_id_mapping *map;
+	struct acpi_rimt_node *parent;
+	int i;
+
+	if (acs_enabled || rimt_node->type != ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX)
+		return;
+
+	pci_rc = (struct acpi_rimt_pcie_rc *)rimt_node->node_data;
+	if (!pci_rc->id_mapping_offset || !pci_rc->num_id_mappings)
+		return;
+
+	map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, rimt_node,
+			   pci_rc->id_mapping_offset);
+
+	for (i = 0; i < pci_rc->num_id_mappings; i++, map++) {
+		if (!map->dest_offset)
+			continue;
+
+		parent = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
+				      map->dest_offset);
+		if (parent->type == ACPI_RIMT_NODE_TYPE_IOMMU) {
+			pci_request_acs();
+			acs_enabled = true;
+			return;
+		}
+	}
+}
+#else
+static inline void rimt_enable_acs(struct acpi_rimt_node *rimt_node) { }
+#endif
+
 /*
  * RISC-V supports IOMMU as a PCI device or a platform device.
  * When it is a platform device, there should be a namespace device as
@@ -509,7 +545,10 @@ int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
 
 void __init riscv_acpi_rimt_init(void)
 {
+	struct acpi_rimt_node *rimt_node, *rimt_end;
+	struct acpi_table_rimt *rimt;
 	acpi_status status;
+	int i;
 
 	/* rimt_table will be used at runtime after the rimt init,
 	 * so we don't need to call acpi_put_table() to release
@@ -525,4 +564,21 @@ void __init riscv_acpi_rimt_init(void)
 
 		return;
 	}
+
+	rimt = (struct acpi_table_rimt *)rimt_table;
+	rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt,
+				 rimt->node_offset);
+	rimt_end = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
+				rimt_table->length);
+
+	for (i = 0; i < rimt->num_nodes; i++) {
+		if (rimt_node >= rimt_end) {
+			pr_err("RIMT node pointer overflows, bad table\n");
+			return;
+		}
+
+		rimt_enable_acs(rimt_node);
+		rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_node,
+					 rimt_node->length);
+	}
 }
-- 
2.50.1
Re: [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
Posted by Sunil V L 3 weeks, 2 days ago 
On Wed, Sep 2, 2026 at 7:31 PM <fangyu.yu@linux.alibaba.com> wrote:
>
> From: Fangyu Yu <fangyu.yu@linux.alibaba.com>
>
> Mirror the ACPI IORT solution used on arm64 (see iort_enable_acs())
> by scanning the RIMT table for PCIe root complex nodes during
> riscv_acpi_rimt_init(), which runs before ACPI PCI enumeration. If a
> root complex node's ID mapping points at an IOMMU node, call
> pci_request_acs() immediately, so pci_acs_enable is already set by
> the time any PCI device is scanned and pci_enable_acs() runs.
>
> Only one call to pci_request_acs() is needed regardless of how many
> root complexes are found, so track that with a static acs_enabled
> flag, same as iort_enable_acs() does.
>
> Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
> ---
>  drivers/acpi/riscv/rimt.c | 56 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 56 insertions(+)
>
> diff --git a/drivers/acpi/riscv/rimt.c b/drivers/acpi/riscv/rimt.c
> index e4538fa6c2c8..f22e28c8211e 100644
> --- a/drivers/acpi/riscv/rimt.c
> +++ b/drivers/acpi/riscv/rimt.c
> @@ -179,6 +179,42 @@ static struct acpi_rimt_node *rimt_scan_node(enum acpi_rimt_node_type type,
>         return NULL;
>  }
>
> +#ifdef CONFIG_PCI
> +static void __init rimt_enable_acs(struct acpi_rimt_node *rimt_node)
> +{
> +       static bool acs_enabled __initdata;
> +       struct acpi_rimt_pcie_rc *pci_rc;
> +       struct acpi_rimt_id_mapping *map;
> +       struct acpi_rimt_node *parent;
> +       int i;
> +
> +       if (acs_enabled || rimt_node->type != ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX)
> +               return;
> +
> +       pci_rc = (struct acpi_rimt_pcie_rc *)rimt_node->node_data;
> +       if (!pci_rc->id_mapping_offset || !pci_rc->num_id_mappings)
> +               return;
> +
> +       map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, rimt_node,
> +                          pci_rc->id_mapping_offset);
> +
> +       for (i = 0; i < pci_rc->num_id_mappings; i++, map++) {
> +               if (!map->dest_offset)
> +                       continue;
> +
> +               parent = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
> +                                     map->dest_offset);
> +               if (parent->type == ACPI_RIMT_NODE_TYPE_IOMMU) {
> +                       pci_request_acs();
> +                       acs_enabled = true;
> +                       return;
> +               }
> +       }
> +}
> +#else
> +static inline void rimt_enable_acs(struct acpi_rimt_node *rimt_node) { }
> +#endif
> +
>  /*
>   * RISC-V supports IOMMU as a PCI device or a platform device.
>   * When it is a platform device, there should be a namespace device as
> @@ -509,7 +545,10 @@ int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
>
>  void __init riscv_acpi_rimt_init(void)
>  {
> +       struct acpi_rimt_node *rimt_node, *rimt_end;
> +       struct acpi_table_rimt *rimt;
>         acpi_status status;
> +       int i;
>
>         /* rimt_table will be used at runtime after the rimt init,
>          * so we don't need to call acpi_put_table() to release
> @@ -525,4 +564,21 @@ void __init riscv_acpi_rimt_init(void)
>
>                 return;
>         }
> +
> +       rimt = (struct acpi_table_rimt *)rimt_table;
> +       rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt,
> +                                rimt->node_offset);
> +       rimt_end = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
> +                               rimt_table->length);
> +
> +       for (i = 0; i < rimt->num_nodes; i++) {
> +               if (rimt_node >= rimt_end) {
> +                       pr_err("RIMT node pointer overflows, bad table\n");
> +                       return;
> +               }
> +
> +               rimt_enable_acs(rimt_node);
>
NIT: Can we check here itself if it is a PCI RC node and then only
call enable_acs()?

> +               rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_node,
> +                                        rimt_node->length);
> +       }
>  }
> --
> 2.50.1
>
Otherwise, LGTM.

Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>
Re: [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
Posted by fangyu.yu@linux.alibaba.com 3 weeks, 2 days ago 
>> From: Fangyu Yu <fangyu.yu@linux.alibaba.com>
>>
>> Mirror the ACPI IORT solution used on arm64 (see iort_enable_acs())
>> by scanning the RIMT table for PCIe root complex nodes during
>> riscv_acpi_rimt_init(), which runs before ACPI PCI enumeration. If a
>> root complex node's ID mapping points at an IOMMU node, call
>> pci_request_acs() immediately, so pci_acs_enable is already set by
>> the time any PCI device is scanned and pci_enable_acs() runs.
>>
>> Only one call to pci_request_acs() is needed regardless of how many
>> root complexes are found, so track that with a static acs_enabled
>> flag, same as iort_enable_acs() does.
>>
>> Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
>> ---
>>  drivers/acpi/riscv/rimt.c | 56 +++++++++++++++++++++++++++++++++++++++
>>  1 file changed, 56 insertions(+)
>>
>> diff --git a/drivers/acpi/riscv/rimt.c b/drivers/acpi/riscv/rimt.c
>> index e4538fa6c2c8..f22e28c8211e 100644
>> --- a/drivers/acpi/riscv/rimt.c
>> +++ b/drivers/acpi/riscv/rimt.c
>> @@ -179,6 +179,42 @@ static struct acpi_rimt_node *rimt_scan_node(enum acpi_rimt_node_type type,
>>         return NULL;
>>  }
>>
>> +#ifdef CONFIG_PCI
>> +static void __init rimt_enable_acs(struct acpi_rimt_node *rimt_node)
>> +{
>> +       static bool acs_enabled __initdata;
>> +       struct acpi_rimt_pcie_rc *pci_rc;
>> +       struct acpi_rimt_id_mapping *map;
>> +       struct acpi_rimt_node *parent;
>> +       int i;
>> +
>> +       if (acs_enabled || rimt_node->type != ACPI_RIMT_NODE_TYPE_PCIE_ROOT_COMPLEX)
>> +               return;
>> +
>> +       pci_rc = (struct acpi_rimt_pcie_rc *)rimt_node->node_data;
>> +       if (!pci_rc->id_mapping_offset || !pci_rc->num_id_mappings)
>> +               return;
>> +
>> +       map = ACPI_ADD_PTR(struct acpi_rimt_id_mapping, rimt_node,
>> +                          pci_rc->id_mapping_offset);
>> +
>> +       for (i = 0; i < pci_rc->num_id_mappings; i++, map++) {
>> +               if (!map->dest_offset)
>> +                       continue;
>> +
>> +               parent = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
>> +                                     map->dest_offset);
>> +               if (parent->type == ACPI_RIMT_NODE_TYPE_IOMMU) {
>> +                       pci_request_acs();
>> +                       acs_enabled = true;
>> +                       return;
>> +               }
>> +       }
>> +}
>> +#else
>> +static inline void rimt_enable_acs(struct acpi_rimt_node *rimt_node) { }
>> +#endif
>> +
>>  /*
>>   * RISC-V supports IOMMU as a PCI device or a platform device.
>>   * When it is a platform device, there should be a namespace device as
>> @@ -509,7 +545,10 @@ int rimt_iommu_configure_id(struct device *dev, const u32 *id_in)
>>
>>  void __init riscv_acpi_rimt_init(void)
>>  {
>> +       struct acpi_rimt_node *rimt_node, *rimt_end;
>> +       struct acpi_table_rimt *rimt;
>>         acpi_status status;
>> +       int i;
>>
>>         /* rimt_table will be used at runtime after the rimt init,
>>          * so we don't need to call acpi_put_table() to release
>> @@ -525,4 +564,21 @@ void __init riscv_acpi_rimt_init(void)
>>
>>                 return;
>>         }
>> +
>> +       rimt = (struct acpi_table_rimt *)rimt_table;
>> +       rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt,
>> +                                rimt->node_offset);
>> +       rimt_end = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_table,
>> +                               rimt_table->length);
>> +
>> +       for (i = 0; i < rimt->num_nodes; i++) {
>> +               if (rimt_node >= rimt_end) {
>> +                       pr_err("RIMT node pointer overflows, bad table\n");
>> +                       return;
>> +               }
>> +
>> +               rimt_enable_acs(rimt_node);
>>
>NIT: Can we check here itself if it is a PCI RC node and then only
>call enable_acs()?
>

Agreed, I will add the PCI RC node check here and invoke enable_acs()
only for that node type.

Thanks,
Fangyu

>> +               rimt_node = ACPI_ADD_PTR(struct acpi_rimt_node, rimt_node,
>> +                                        rimt_node->length);
>> +       }
>>  }
>> --
>> 2.50.1
>>
>Otherwise, LGTM.
>
>Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>

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