[RFC PATCH v2 2/4] acpi: fadt: support revision 6.0 of the ACPI specification

[Miguel Luis]

Update the Fixed ACPI Description Table (FADT) to revision 6.0 of the ACPI
specification adding the field "Hypervisor Vendor Identity" that was missing.

This field's description states the following: "64-bit identifier of hypervisor
vendor. All bytes in this field are considered part of the vendor identity.
These identifiers are defined independently by the vendors themselves,
usually following the name of the hypervisor product. Version information
should NOT be included in this field - this shall simply denote the vendor's
name or identifier. Version information can be communicated through a
supplemental vendor-specific hypervisor API. Firmware implementers would
place zero bytes into this field, denoting that no hypervisor is present in
the actual firmware."

Hereupon, what should a valid identifier of an Hypervisor Vendor ID be and
where should QEMU provide that information?

On the v1 [1] of this RFC there's the suggestion of having this information
in sync by the current acceleration name. This also seems to imply that QEMU,
which generates the FADT table, and the FADT consumer need to be in sync with
the values of this field.

This version follows Ani Sinha's suggestion [2] of using "QEMU" for the
hypervisor vendor ID.

[1]: https://lists.nongnu.org/archive/html/qemu-devel/2022-10/msg00911.html
[2]: https://lists.nongnu.org/archive/html/qemu-devel/2022-10/msg00989.html

Signed-off-by: Miguel Luis <miguel.luis@oracle.com>
---
 hw/acpi/aml-build.c      | 13 ++++++++++---
 hw/arm/virt-acpi-build.c | 10 +++++-----
 2 files changed, 15 insertions(+), 8 deletions(-)

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index e6bfac95c7..42feb4d4d7 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2070,7 +2070,7 @@ void build_pptt(GArray *table_data, BIOSLinker *linker, 
MachineState *ms,
     acpi_table_end(linker, &table);
 }
 
-/* build rev1/rev3/rev5.1 FADT */
+/* build rev1/rev3/rev5.1/rev6.0 FADT */
 void build_fadt(GArray *tbl, BIOSLinker *linker, const AcpiFadtData *f,
                 const char *oem_id, const char *oem_table_id)
 {
@@ -2193,8 +2193,15 @@ void build_fadt(GArray *tbl, BIOSLinker *linker, const 
AcpiFadtData *f,
     /* SLEEP_STATUS_REG */
     build_append_gas_from_struct(tbl, &f->sleep_sts);
 
-    /* TODO: extra fields need to be added to support revisions above rev5 */
-    assert(f->rev == 5);
+    if (f->rev == 5) {
+        goto done;
+    }
+
+    /* Hypervisor Vendor Identity */
+    build_append_padded_str(tbl, "QEMU", 8, '\0');
+
+    /* TODO: extra fields need to be added to support revisions above rev6 */
+    assert(f->rev == 6);
 
 done:
     acpi_table_end(linker, &table);
diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 9b3aee01bf..72bb6f61a5 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -809,13 +809,13 @@ build_madt(GArray *table_data, BIOSLinker *linker, 
VirtMachineState *vms)
 }
 
 /* FADT */
-static void build_fadt_rev5(GArray *table_data, BIOSLinker *linker,
+static void build_fadt_rev6(GArray *table_data, BIOSLinker *linker,
                             VirtMachineState *vms, unsigned dsdt_tbl_offset)
 {
-    /* ACPI v5.1 */
+    /* ACPI v6.0 */
     AcpiFadtData fadt = {
-        .rev = 5,
-        .minor_ver = 1,
+        .rev = 6,
+        .minor_ver = 0,
         .flags = 1 << ACPI_FADT_F_HW_REDUCED_ACPI,
         .xdsdt_tbl_offset = &dsdt_tbl_offset,
     };
@@ -945,7 +945,7 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables 
*tables)
 
     /* FADT MADT PPTT GTDT MCFG SPCR DBG2 pointed to by RSDT */
     acpi_add_table(table_offsets, tables_blob);
-    build_fadt_rev5(tables_blob, tables->linker, vms, dsdt);
+    build_fadt_rev6(tables_blob, tables->linker, vms, dsdt);
 
     acpi_add_table(table_offsets, tables_blob);
     build_madt(tables_blob, tables->linker, vms);
-- 
2.37.3