acpi: add helper routines to initialize ACPI tables

Patch introduces acpi_table_begin()/ acpi_table_end() API
that hides pointer/offset arithmetic from user as opposed
to build_header(), to prevent errors caused by it [1].

 acpi_table_begin():
     initializes table header and keeps track of
     table data/offsets
 acpi_table_end():
     sets actual table length and tells bios loader
     where table is for the later initialization on
     guest side.

1) commits
   bb9feea43179 x86: acpi: use offset instead of pointer when using build_header()
   4d027afeb3a9 Virt: ACPI: fix qemu assert due to re-assigned table data address

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Message-Id: <20210924122802.1455362-2-imammedo@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Stefan Berger <stefanb@linux.ibm.com>
Tested-by: Yanan Wang <wangyanan55@huawei.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/hw/acpi/aml-build.h b/include/hw/acpi/aml-build.h
index 471266d..4242382 100644
--- a/include/hw/acpi/aml-build.h
+++ b/include/hw/acpi/aml-build.h
@@ -413,6 +413,37 @@ Aml *aml_concatenate(Aml *source1, Aml *source2, Aml *target);
 Aml *aml_object_type(Aml *object);
 
 void build_append_int_noprefix(GArray *table, uint64_t value, int size);
+
+typedef struct AcpiTable {
+    const char *sig;
+    const uint8_t rev;
+    const char *oem_id;
+    const char *oem_table_id;
+    /* private vars tracking table state */
+    GArray *array;
+    unsigned table_offset;
+} AcpiTable;
+
+/**
+ * acpi_table_begin:
+ * initializes table header and keeps track of
+ * table data/offsets
+ * @desc: ACPI table descriptor
+ * @array: blob where the ACPI table will be composed/stored.
+ */
+void acpi_table_begin(AcpiTable *desc, GArray *array);
+
+/**
+ * acpi_table_end:
+ * sets actual table length and tells bios loader
+ * where table is for the later initialization on
+ * guest side.
+ * @linker: reference to BIOSLinker object to use for the table
+ * @table: ACPI table descriptor that was used with @acpi_table_begin
+ * counterpart
+ */
+void acpi_table_end(BIOSLinker *linker, AcpiTable *table);
+
 void
 build_header(BIOSLinker *linker, GArray *table_data,
              AcpiTableHeader *h, const char *sig, int len, uint8_t rev,