hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

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.

The 8042 bit in IAPC_BOOT_ARCH was introduced from ACPI spec v2 (FADT
revision 2 and above). Therefore, in this change, we only enable this bit for
x86/q35 machine types since x86/i440fx machines use FADT ACPI table with
revision 1.

Signed-off-by: Liav Albani <liavalb@gmail.com>
Signed-off-by: Ani Sinha <ani@anisinha.ca>
Message-Id: <20220304154032.2071585-3-ani@anisinha.ca>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

4 files changed, 31 insertions, 1 deletions

diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
index 8966e16..1773cf5 100644
--- a/hw/acpi/aml-build.c
+++ b/hw/acpi/aml-build.c
@@ -2152,7 +2152,13 @@ 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 {
+        /* since ACPI v2.0 */
+        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 ebd47aa..4ad4d72 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -38,6 +38,7 @@
 #include "hw/nvram/fw_cfg.h"
 #include "hw/acpi/bios-linker-loader.h"
 #include "hw/isa/isa.h"
+#include "hw/input/i8042.h"
 #include "hw/block/fdc.h"
 #include "hw/acpi/memory_hotplug.h"
 #include "sysemu/tpm.h"
@@ -192,6 +193,13 @@ static void init_common_fadt_data(MachineState *ms, Object *o,
             .address = object_property_get_uint(o, ACPI_PM_PROP_GPE0_BLK, NULL)
         },
     };
+
+    /*
+     * ACPI v2, Table 5-10 - Fixed ACPI Description Table Boot Architecture
+     * Flags, bit offset 1 - 8042.
+     */
+    fadt.iapc_boot_arch = iapc_boot_arch_8042();
+
     *data = fadt;
 }
 
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index c97e863..2b42e41 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 */
 
     /*
diff --git a/include/hw/input/i8042.h b/include/hw/input/i8042.h
index 1d90432..e070f54 100644
--- a/include/hw/input/i8042.h
+++ b/include/hw/input/i8042.h
@@ -23,4 +23,19 @@ void i8042_mm_init(qemu_irq kbd_irq, qemu_irq mouse_irq,
 void i8042_isa_mouse_fake_event(ISAKBDState *isa);
 void i8042_setup_a20_line(ISADevice *dev, qemu_irq a20_out);
 
+static inline bool i8042_present(void)
+{
+    bool amb = false;
+    return object_resolve_path_type("", TYPE_I8042, &amb) || amb;
+}
+
+/*
+ * ACPI v2, Table 5-10 - Fixed ACPI Description Table Boot Architecture
+ * Flags, bit offset 1 - 8042.
+ */
+static inline uint16_t iapc_boot_arch_8042(void)
+{
+    return i8042_present() ? 0x1 << 1 : 0x0 ;
+}
+
 #endif /* HW_INPUT_I8042_H */