[PATCH v3 3/4] hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

[Liav Albani]

This can allow the guest OS to determine more easily if i8042 controller
is present in the system or not, so it doesn't need to do probing of the
controller, but just initialize it immediately, before enumerating the
ACPI AML namespace.

Signed-off-by: Liav Albani <liavalb@gmail.com>
---
 hw/acpi/aml-build.c         | 7 ++++++-
 hw/i386/acpi-build.c        | 8 ++++++++
 hw/i386/acpi-microvm.c      | 9 +++++++++
 include/hw/acpi/acpi-defs.h | 1 +
 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index 8966e16320..ef5f4cad87 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2152,7 +2152,12 @@ void build_fadt(GArray *tbl, BIOSLinker *linker, const 
AcpiFadtData *f,
     build_append_int_noprefix(tbl, 0, 1); /* DAY_ALRM */
     build_append_int_noprefix(tbl, 0, 1); /* MON_ALRM */
     build_append_int_noprefix(tbl, f->rtc_century, 1); /* CENTURY */
-    build_append_int_noprefix(tbl, 0, 2); /* IAPC_BOOT_ARCH */
+    /* IAPC_BOOT_ARCH */
+    if (f->rev == 1) {
+        build_append_int_noprefix(tbl, 0, 2);
+    } else {
+        build_append_int_noprefix(tbl, f->iapc_boot_arch, 2);
+    }
     build_append_int_noprefix(tbl, 0, 1); /* Reserved */
     build_append_int_noprefix(tbl, f->flags, 4); /* Flags */
 
diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index ebd47aa26f..65dbc1ec36 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -192,6 +192,14 @@ static void init_common_fadt_data(MachineState *ms, Object 
*o,
             .address = object_property_get_uint(o, ACPI_PM_PROP_GPE0_BLK, NULL)
         },
     };
+    /*
+     * second bit of 16 but IAPC_BOOT_ARCH indicates presence of 8042 or
+     * equivalent micro controller. See table 5-10 of APCI spec version 2.0
+     * (the earliest acpi revision that supports this).
+     */
+
+    fadt.iapc_boot_arch = isa_check_device_existence("i8042") ? 0x0002 : 
0x0000;
+
     *data = fadt;
 }
 
diff --git a/hw/i386/acpi-microvm.c b/hw/i386/acpi-microvm.c
index 68ca7e7fc2..e5f89164be 100644
--- a/hw/i386/acpi-microvm.c
+++ b/hw/i386/acpi-microvm.c
@@ -189,6 +189,15 @@ static void acpi_build_microvm(AcpiBuildTables *tables,
         .reset_val = ACPI_GED_RESET_VALUE,
     };
 
+    /*
+     * second bit of 16 but IAPC_BOOT_ARCH indicates presence of 8042 or
+     * equivalent micro controller. See table 5-10 of APCI spec version 2.0
+     * (the earliest acpi revision that supports this).
+     */
+
+    pmfadt.iapc_boot_arch = isa_check_device_existence("i8042") ? 0x0002
+                            : 0x0000;
+
     table_offsets = g_array_new(false, true /* clear */,
                                         sizeof(uint32_t));
     bios_linker_loader_alloc(tables->linker,
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index c97e8633ad..2b42e4192b 100644
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -77,6 +77,7 @@ typedef struct AcpiFadtData {
     uint16_t plvl2_lat;        /* P_LVL2_LAT */
     uint16_t plvl3_lat;        /* P_LVL3_LAT */
     uint16_t arm_boot_arch;    /* ARM_BOOT_ARCH */
+    uint16_t iapc_boot_arch;   /* IAPC_BOOT_ARCH */
     uint8_t minor_ver;         /* FADT Minor Version */
 
     /*
-- 
2.35.1