* [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
@ 2026-09-02 14:01 fangyu.yu
2026-09-03 4:45 ` Sunil V L
0 siblings, 1 reply; 3+ messages in thread
From: fangyu.yu @ 2026-09-02 14:01 UTC (permalink / raw)
To: sunilvl, sunilvl, rafael, lenb, pjw, palmer, aou, alex
Cc: fangyu.yu, guoren, linux-acpi, iommu, linux-kernel, linux-riscv
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
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^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
2026-09-02 14:01 [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU fangyu.yu
@ 2026-09-03 4:45 ` Sunil V L
2026-09-03 7:44 ` fangyu.yu
0 siblings, 1 reply; 3+ messages in thread
From: Sunil V L @ 2026-09-03 4:45 UTC (permalink / raw)
To: fangyu.yu
Cc: aou, alex, rafael, linux-kernel, linux-acpi, iommu, palmer,
guoren, pjw, linux-riscv, lenb
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>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU
2026-09-03 4:45 ` Sunil V L
@ 2026-09-03 7:44 ` fangyu.yu
0 siblings, 0 replies; 3+ messages in thread
From: fangyu.yu @ 2026-09-03 7:44 UTC (permalink / raw)
To: sunilvl
Cc: alex, aou, fangyu.yu, guoren, iommu, lenb, linux-acpi,
linux-kernel, linux-riscv, palmer, pjw, rafael
>> 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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http://lists.infradead.org/mailman/listinfo/linux-riscv
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2026-09-02 14:01 [PATCH] ACPI: RIMT: Enable PCI ACS for root complexes mapped to an IOMMU fangyu.yu
2026-09-03 4:45 ` Sunil V L
2026-09-03 7:44 ` fangyu.yu
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