Re: [Qemu-devel] [PATCH v2 2/2] ARM: Virt: ACPI: Build an IORT table with RC and ITS nodes

[Andrew Jones]

On Fri, Oct 14, 2016 at 10:54:55AM +0200, Eric Auger wrote:
> From: Prem Mallappa <address@hidden>
> 
> This patch builds an IORT table that features a root complex node and
> an ITS node. This complements the ITS description in the ACPI MADT
> table and allows vhost-net on ACPI guest.
> 
> Signed-off-by: Prem Mallappa <address@hidden>
> Signed-off-by: Eric Auger <address@hidden>
> 
> ---
> 
> v1 -> v2:
> - its_class_name() || !guest_info->no_its now wraps acpi_add_table
>   and build_iort
> - add cpu_to_le*
> - CCA = CPM = DACS = 1
> - cleanup according to Drew's comments
> - remove comments listing tables and spec revisions
> ---
>  hw/arm/virt-acpi-build.c | 73 
> ++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 62 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index fa0655a..5fc0fd7 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -384,6 +384,63 @@ build_rsdp(GArray *rsdp_table, BIOSLinker *linker, 
> unsigned rsdt_tbl_offset)
>  }
>  
>  static void
> +build_iort(GArray *table_data, BIOSLinker *linker, VirtGuestInfo *guest_info)
> +{
> +    int iort_start = table_data->len;
> +    AcpiIortIdMapping *idmap;
> +    AcpiIortItsGroup *its;
> +    AcpiIortTable *iort;
> +    size_t node_size, iort_length;
> +    AcpiIortRC *rc;
> +
> +    iort = acpi_data_push(table_data, sizeof(*iort));
> +
> +    iort_length = sizeof(*iort);
> +    iort->node_count = cpu_to_le32(2); /* RC and ITS nodes */
> +    iort->node_offset = cpu_to_le32(table_data->len - iort_start);

table_data->len - iort_start = sizeof(*iort), I think the later would
be nicer to use.

> +
> +    /* ITS group node */
> +    node_size =  sizeof(*its) + sizeof(uint32_t);
> +    iort_length += node_size;
> +    its = acpi_data_push(table_data, node_size);
> +
> +    its->type = ACPI_IORT_NODE_ITS_GROUP;
> +    its->length = cpu_to_le16(node_size);
unnecessary blank line
> +
> +    its->its_count = cpu_to_le32(1);
> +    its->identifiers[0] = 0; /* madt translation_id = 0 */

/madt/MADT/
can probably drop the '= 0' in the comment

> +
> +    /* Root Complex Node */
> +    node_size = sizeof(*rc) + sizeof(*idmap);
> +    iort_length += node_size;
> +    rc = acpi_data_push(table_data, node_size);
> +
> +    rc->type = ACPI_IORT_NODE_PCI_ROOT_COMPLEX;
> +    rc->length = cpu_to_le16(node_size);
unnecessary blank line
> +
> +    rc->mapping_count = cpu_to_le32(1);
> +    rc->mapping_offset = cpu_to_le32(sizeof(*rc));
> +
> +    /* fully coherent device */
> +    rc->memory_properties.cache_coherency = cpu_to_le32(1);
> +    rc->memory_properties.memory_flags = 0x3; /* CCA = CPM = DCAS = 1 */
> +    rc->pci_segment_number = 0; /* MCFG pci_segment */
> +
> +    /* Identity RID mapping covering the whole input RID range */
> +    idmap = &rc->id_mapping_array[0];
> +    idmap->input_base = 0;
> +    idmap->id_count = cpu_to_le32(0xFFFF);
> +    idmap->output_base = 0;
> +    idmap->output_reference = cpu_to_le32(iort->node_offset);

I'd still like a comment for output_reference stating that this is where
we're mapping the output of the root complex to the ITS group node.

> +    idmap->flags = 0;

I think we can drop this flags assignment, otherwise we need to comment
it.

> +
> +    iort->length = cpu_to_le32(iort_length);
> +
> +    build_header(linker, table_data, (void *)(table_data->data + iort_start),
> +                 "IORT", table_data->len - iort_start, 0, NULL, NULL);
> +}
> +
> +static void
>  build_spcr(GArray *table_data, BIOSLinker *linker, VirtGuestInfo *guest_info)
>  {
>      AcpiSerialPortConsoleRedirection *spcr;
> @@ -667,17 +724,6 @@ void virt_acpi_build(VirtGuestInfo *guest_info, 
> AcpiBuildTables *tables)
>                               ACPI_BUILD_TABLE_FILE, tables_blob,
>                               64, false /* high memory */);
>  
> -    /*
> -     * The ACPI v5.1 tables for Hardware-reduced ACPI platform are:
> -     * RSDP
> -     * RSDT
> -     * FADT
> -     * GTDT
> -     * MADT
> -     * MCFG
> -     * DSDT
> -     */
> -
>      /* DSDT is pointed to by FADT */
>      dsdt = tables_blob->len;
>      build_dsdt(tables_blob, tables->linker, guest_info);
> @@ -703,6 +749,11 @@ void virt_acpi_build(VirtGuestInfo *guest_info, 
> AcpiBuildTables *tables)
>          build_srat(tables_blob, tables->linker, guest_info);
>      }
>  
> +    if (its_class_name() && !guest_info->no_its) {
> +        acpi_add_table(table_offsets, tables_blob);
> +        build_iort(tables_blob, tables->linker, guest_info);
> +    }
> +
>      /* RSDT is pointed to by RSDP */
>      rsdt = tables_blob->len;
>      build_rsdt(tables_blob, tables->linker, table_offsets, NULL, NULL);
> -- 
> 2.5.5
> 
>

Thanks,
drew