| Message ID | 20250616131824.425315-5-gustavo.romero@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | hw/arm: GIC 'its=off' ACPI table fixes | expand |
Hi Gustavo, On 6/16/25 3:18 PM, Gustavo Romero wrote: > The comment about the mapping from SMMU to ITS is incorrect and it reads > "RC -> ITS". The code in question actually maps SMMU -> ITS, so the > mapping in question is not direct. The direct mapping, i.e., RC -> ITS, > is handled a bit further down in the code, in the else block, and we > take the opportunity to update that as well, adding "RC -> ITS" to the > text so it's easier to see it's the direct map to the ITS Group node. > > Signed-off-by Gustavo Romero <gustavo.romero@linaro.org> > --- > hw/arm/virt-acpi-build.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c > index 9eee284c80..6990bce3bb 100644 > --- a/hw/arm/virt-acpi-build.c > +++ b/hw/arm/virt-acpi-build.c > @@ -407,23 +407,27 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) > if (vms->iommu == VIRT_IOMMU_SMMUV3) { > AcpiIortIdMapping *range; > > - /* translated RIDs connect to SMMUv3 node: RC -> SMMUv3 -> ITS */ > + /* Map RIDs (input) from RC to SMMUv3 nodes: RC -> SMMUv3. */ yes this is what the code builds at this location. > for (i = 0; i < smmu_idmaps->len; i++) { > range = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i); > - /* output IORT node is the smmuv3 node */ > + /* Output IORT node is the SMMUv3 node. */ > build_iort_id_mapping(table_data, range->input_base, > range->id_count, smmu_offset); > } > > - /* bypassed RIDs connect to ITS group node directly: RC -> ITS */ > + /* Map DeviceIDs (input) from SMMUv3 to ITS Group nodes: SMMU -> ITS. */ But here I am confused. To me the its_idmaps matches the idmap between RC and ITS. I understand this is built from holes left by bypassed buses. See the build_iort() implementation. The comment at /* * Split the whole RIDs by mapping from RC to SMMU, * build the ID mapping from RC to ITS directly. */ for (i = 0; i < smmu_idmaps->len; i++) { idmap = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i); if (next_range.input_base < idmap->input_base) { next_range.id_count = idmap->input_base - next_range.input_base; g_array_append_val(its_idmaps, next_range); } next_range.input_base = idmap->input_base + idmap->id_count; } is not crystal clear but it looks like filling the holes into its_idmap. Besides there is another "Its group" instance to be replaced by ITS Group Eric > for (i = 0; i < its_idmaps->len; i++) { > range = &g_array_index(its_idmaps, AcpiIortIdMapping, i); > - /* output IORT node is the ITS group node (the first node) */ > + /* Output IORT node is the ITS Group node (the first node). */ > build_iort_id_mapping(table_data, range->input_base, > range->id_count, IORT_NODE_OFFSET); > } > } else { > - /* output IORT node is the ITS group node (the first node) */ > + /* > + * Map bypassed RIDs (input) (don't go through the SMMU) to ITS Group > + * nodes: RC -> ITS. > + * Output IORT node is the ITS Group node (the first node). > + */ > build_iort_id_mapping(table_data, 0, 0x10000, IORT_NODE_OFFSET); > } >
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c index 9eee284c80..6990bce3bb 100644 --- a/hw/arm/virt-acpi-build.c +++ b/hw/arm/virt-acpi-build.c @@ -407,23 +407,27 @@ build_iort(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms) if (vms->iommu == VIRT_IOMMU_SMMUV3) { AcpiIortIdMapping *range; - /* translated RIDs connect to SMMUv3 node: RC -> SMMUv3 -> ITS */ + /* Map RIDs (input) from RC to SMMUv3 nodes: RC -> SMMUv3. */ for (i = 0; i < smmu_idmaps->len; i++) { range = &g_array_index(smmu_idmaps, AcpiIortIdMapping, i); - /* output IORT node is the smmuv3 node */ + /* Output IORT node is the SMMUv3 node. */ build_iort_id_mapping(table_data, range->input_base, range->id_count, smmu_offset); } - /* bypassed RIDs connect to ITS group node directly: RC -> ITS */ + /* Map DeviceIDs (input) from SMMUv3 to ITS Group nodes: SMMU -> ITS. */ for (i = 0; i < its_idmaps->len; i++) { range = &g_array_index(its_idmaps, AcpiIortIdMapping, i); - /* output IORT node is the ITS group node (the first node) */ + /* Output IORT node is the ITS Group node (the first node). */ build_iort_id_mapping(table_data, range->input_base, range->id_count, IORT_NODE_OFFSET); } } else { - /* output IORT node is the ITS group node (the first node) */ + /* + * Map bypassed RIDs (input) (don't go through the SMMU) to ITS Group + * nodes: RC -> ITS. + * Output IORT node is the ITS Group node (the first node). + */ build_iort_id_mapping(table_data, 0, 0x10000, IORT_NODE_OFFSET); }