Re: [PATCH v3 12/35] acpi: vmgenid_build_acpi: use acpi_table_begin()/acpi_table_end() instead of build_header()

[Igor Mammedov <imammedo@redhat.com>]

On Wed, 22 Sep 2021 09:23:16 +0200
Eric Auger <eauger@redhat.com> wrote:

> On 9/7/21 4:47 PM, Igor Mammedov wrote:
> > it replaces error-prone pointer arithmetic for build_header() API,
> > with 2 calls to start and finish table creation,
> > which hides offsets magic from API user.
> > 
> > Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> > ---
> > v3:
> >   * s/acpi_init_table|acpi_table_composed/acpi_table_begin|acpi_table_end/
> > ---
> >  hw/acpi/vmgenid.c | 16 +++++++---------
> >  1 file changed, 7 insertions(+), 9 deletions(-)
> > 
> > diff --git a/hw/acpi/vmgenid.c b/hw/acpi/vmgenid.c
> > index 4f41a13ea0..95f94a2510 100644
> > --- a/hw/acpi/vmgenid.c
> > +++ b/hw/acpi/vmgenid.c
> > @@ -29,6 +29,8 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
> >      Aml *ssdt, *dev, *scope, *method, *addr, *if_ctx;
> >      uint32_t vgia_offset;
> >      QemuUUID guid_le;
> > +    AcpiTable table = { .sig = "SSDT", .rev = 1,
> > +                        .oem_id = oem_id, .oem_table_id = "VMGENID" };
> >  
> >      /* Fill in the GUID values.  These need to be converted to little-endian
> >       * first, since that's what the guest expects
> > @@ -42,15 +44,12 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
> >      g_array_insert_vals(guid, VMGENID_GUID_OFFSET, guid_le.data,
> >                          ARRAY_SIZE(guid_le.data));
> >  
> > -    /* Put this in a separate SSDT table */
> > +    /* Put VMGNEID into a separate SSDT table */
> > +    acpi_table_begin(&table, table_data);
> >      ssdt = init_aml_allocator();
> >  
> > -    /* Reserve space for header */
> > -    acpi_data_push(ssdt->buf, sizeof(AcpiTableHeader));
> > -
> >      /* Storage for the GUID address */
> > -    vgia_offset = table_data->len +
> > -        build_append_named_dword(ssdt->buf, "VGIA");
> > +    vgia_offset = table_data->len + build_append_named_dword(ssdt->buf, "VGIA");  
> not mandated but well

dropped

> 
> >      scope = aml_scope("\\_SB");
> >      dev = aml_device("VGEN");
> >      aml_append(dev, aml_name_decl("_HID", aml_string("QEMUVGID")));
> > @@ -116,9 +115,8 @@ void vmgenid_build_acpi(VmGenIdState *vms, GArray *table_data, GArray *guid,
> >          ACPI_BUILD_TABLE_FILE, vgia_offset, sizeof(uint32_t),
> >          VMGENID_GUID_FW_CFG_FILE, 0);
> >  
> > -    build_header(linker, table_data,
> > -        (void *)(table_data->data + table_data->len - ssdt->buf->len),
> > -        "SSDT", ssdt->buf->len, 1, oem_id, "VMGENID");
> > +    /* must be called after above command to ensure correct table checksum */  
> ditto
I'd prefer to keep this reminder until there is a way to
enforce valid order.

> > +    acpi_table_end(linker, &table);
> >      free_aml_allocator();
> >  }
> >  
> >   
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> 
> Eric
>