Re: [PATCH-for-10.1 v3 7/9] hw/arm/virt-acpi: Always build IORT table (even with GIC ITS disabled)

[Eric Auger]

Hi Philippe,

On 4/3/25 10:40 PM, Philippe Mathieu-Daudé wrote:
> Citing Gustavo [*]:
>
>   Gating IORT table generation entirely based on the presence
>   of ITS looks wrong because IORT table has data beyond GIC ITS,
>   like for SMMUv3 etc..
> [*] 
> bae6e29a-7290-47d2-8caf-14702ee091f0@linaro.org/">https://lore.kernel.org/qemu-devel/bae6e29a-7290-47d2-8caf-14702ee091f0@linaro.org/
>
> Reported-by: Gustavo Romero <gustavo.romero@linaro.org>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> ---
>  hw/arm/virt-acpi-build.c | 38 +++++++++++++++++++++-----------------
>  1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 1c389ef5cdb..e7e27951cb9 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -287,6 +287,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, 
> VirtMachineState *vms)
>      uint32_t id = 0;
>      GArray *smmu_idmaps = g_array_new(false, true, 
> sizeof(AcpiIortIdMapping));
>      GArray *its_idmaps = g_array_new(false, true, sizeof(AcpiIortIdMapping));
> +    bool has_its = its_enabled(vms);
>  
>      AcpiTable table = { .sig = "IORT", .rev = 3, .oem_id = vms->oem_id,
>                          .oem_table_id = vms->oem_table_id };
> @@ -325,9 +326,12 @@ build_iort(GArray *table_data, BIOSLinker *linker, 
> VirtMachineState *vms)
>  
>          nb_nodes = 3; /* RC, ITS, SMMUv3 */
>          rc_mapping_count = smmu_idmaps->len + its_idmaps->len;
> -    } else {
> +    } else if (has_its) {
>          nb_nodes = 2; /* RC, ITS */
>          rc_mapping_count = 1;
> +    } else {
> +        nb_nodes = 1; /* RC */
> +        rc_mapping_count = 1;
>      }
>      /* Number of IORT Nodes */
>      build_append_int_noprefix(table_data, nb_nodes, 4);
> @@ -336,17 +340,19 @@ build_iort(GArray *table_data, BIOSLinker *linker, 
> VirtMachineState *vms)
>      build_append_int_noprefix(table_data, IORT_NODE_OFFSET, 4);
>      build_append_int_noprefix(table_data, 0, 4); /* Reserved */
>  
> -    /* Table 12 ITS Group Format */
> -    build_append_int_noprefix(table_data, 0 /* ITS Group */, 1); /* Type */
> -    node_size =  20 /* fixed header size */ + 4 /* 1 GIC ITS Identifier */;
> -    build_append_int_noprefix(table_data, node_size, 2); /* Length */
> -    build_append_int_noprefix(table_data, 1, 1); /* Revision */
> -    build_append_int_noprefix(table_data, id++, 4); /* Identifier */
> -    build_append_int_noprefix(table_data, 0, 4); /* Number of ID mappings */
> -    build_append_int_noprefix(table_data, 0, 4); /* Reference to ID Array */
> -    build_append_int_noprefix(table_data, 1, 4); /* Number of ITSs */
> -    /* GIC ITS Identifier Array */
> -    build_append_int_noprefix(table_data, 0 /* MADT translation_id */, 4);
> +    if (has_its) {
> +        /* Table 12 ITS Group Format */
> +        build_append_int_noprefix(table_data, 0 /* ITS Group */, 1); /* Type 
> */ //
> +        node_size =  20 /* fixed header size */ + 4 /* 1 GIC ITS Identifier 
> */;
> +        build_append_int_noprefix(table_data, node_size, 2); /* Length */
> +        build_append_int_noprefix(table_data, 1, 1); /* Revision */
> +        build_append_int_noprefix(table_data, id++, 4); /* Identifier */
> +        build_append_int_noprefix(table_data, 0, 4); /* Number of ID 
> mappings */
> +        build_append_int_noprefix(table_data, 0, 4); /* Reference to ID 
> Array */
> +        build_append_int_noprefix(table_data, 1, 4); /* Number of ITSs */
> +        /* GIC ITS Identifier Array */
> +        build_append_int_noprefix(table_data, 0 /* MADT translation_id */, 
> 4);
> +    }
Do we allow configs where we have SMMU and no ITS?

The IORT spec says "
ID mappings that are defined in an SMMU IORT node can only have an ITS
Group node as an output reference,
or no IDs in the case of a system that does not have ITS units. All
other object types are explicitly forbidden.
"
So in case we do not have any ITS we also need to take care of ID
mappings of SMMUs

Eric
>  
>      if (vms->iommu == VIRT_IOMMU_SMMUV3) {
>          int irq =  vms->irqmap[VIRT_SMMU] + ARM_SPI_BASE;
> @@ -429,7 +435,7 @@ build_iort(GArray *table_data, BIOSLinker *linker, 
> VirtMachineState *vms)
>              build_iort_id_mapping(table_data, range->input_base,
>                                    range->id_count, IORT_NODE_OFFSET);
>          }
> -    } else {
> +    } else if (has_its) {
>          /* output IORT node is the ITS group node (the first node) */
>          build_iort_id_mapping(table_data, 0, 0x10000, IORT_NODE_OFFSET);
>      }
> @@ -979,10 +985,8 @@ void virt_acpi_build(VirtMachineState *vms, 
> AcpiBuildTables *tables)
>                            vms->oem_table_id);
>      }
>  
> -    if (its_enabled(vms)) {
> -        acpi_add_table(table_offsets, tables_blob);
> -        build_iort(tables_blob, tables->linker, vms);
> -    }
> +    acpi_add_table(table_offsets, tables_blob);
> +    build_iort(tables_blob, tables->linker, vms);
>  
>  #ifdef CONFIG_TPM
>      if (tpm_get_version(tpm_find()) == TPM_VERSION_2_0) {