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

[Ani Sinha]

On Mon, Feb 28, 2022 at 3:03 AM Bernhard Beschow <shentey@gmail.com> wrote:
>
> Am 27. Februar 2022 18:58:18 UTC schrieb Liav Albani <liavalb@gmail.com>:
> >
> >On 2/27/22 12:48, Bernhard Beschow wrote:
> >> Am 26. Februar 2022 06:30:18 UTC schrieb Liav Albani <liavalb@gmail.com>:
> >>> 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;
> >> Couldn't qdev_find_recursive() be used here instead? This would also make 
> >> patch 1 unneccessary. Same below.
> >>
> >> Best regards
> >> Bernhard
> >
> >I tried it first, but because it tries to find the ID of a device
> >instead of a type (I look for i8042 type which is a string of the device
> >type), it didn't work as expected. We don't compare DeviceState id, but
> >ObjectClass type->name here :)
>
> I see. What about object_resolve_path_type()? It takes a typename parameter. 
> It even tells you if the match is ambiguous if you care.

Yes this is a good suggestion and it will likely work.
You can get rid of your first patch and only make the following change:

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 65dbc1ec36..d82c39490c 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"
@@ -198,7 +199,7 @@ static void init_common_fadt_data(MachineState
*ms, Object *o,
      * (the earliest acpi revision that supports this).
      */

-    fadt.iapc_boot_arch = isa_check_device_existence("i8042") ?
0x0002 : 0x0000;
+    fadt.iapc_boot_arch = object_resolve_path_type("", TYPE_I8042,
NULL) ? 0x0002 : 0x0000;

     *data = fadt;
 }
diff --git a/hw/i386/acpi-microvm.c b/hw/i386/acpi-microvm.c
index e5f89164be..502ae61a17 100644
--- a/hw/i386/acpi-microvm.c
+++ b/hw/i386/acpi-microvm.c
@@ -33,6 +33,7 @@
 #include "hw/acpi/erst.h"
 #include "hw/i386/fw_cfg.h"
 #include "hw/i386/microvm.h"
+#include "hw/input/i8042.h"
 #include "hw/pci/pci.h"
 #include "hw/pci/pcie_host.h"
 #include "hw/usb/xhci.h"
@@ -195,7 +196,7 @@ static void acpi_build_microvm(AcpiBuildTables *tables,
      * (the earliest acpi revision that supports this).
      */

-    pmfadt.iapc_boot_arch = isa_check_device_existence("i8042") ? 0x0002
+    pmfadt.iapc_boot_arch = object_resolve_path_type("", TYPE_I8042,
NULL) ? 0x0002
                             : 0x0000;

     table_offsets = g_array_new(false, true /* clear */,

Please re-test your change.