Re: [PATCH v4 2/3] hw/acpi: add indication for i8042 in IA-PC boot flags of the FADT table

[Igor Mammedov]

On Mon, 28 Feb 2022 22:17:32 +0200
Liav Albani <liavalb@gmail.com> wrote:

> 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.
> 
> This change only applies to the x86/q35 machine type, as it uses FACP
> ACPI table with revision higher than 1, which should implement at least
> ACPI 2.0 features within the table, hence it can also set the IA-PC boot
> flags register according to the ACPI 2.0 specification.
> 
> Signed-off-by: Liav Albani <liavalb@gmail.com>
> ---
>  hw/acpi/aml-build.c         | 11 ++++++++++-
>  hw/i386/acpi-build.c        |  9 +++++++++
>  hw/i386/acpi-microvm.c      |  9 +++++++++
commit message says it's q35 specific, so wy it touched microvm anc piix4?

>  include/hw/acpi/acpi-defs.h |  1 +
>  4 files changed, 29 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/acpi/aml-build.c b/hw/acpi/aml-build.c
> index 8966e16320..2085905b83 100644
> --- a/hw/acpi/aml-build.c
> +++ b/hw/acpi/aml-build.c
> @@ -2152,7 +2152,16 @@ 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 */
> +    /*
> +     * This register is not defined in ACPI spec version 1.0, where the FACP
> +     * revision == 1 also applies. Therefore, just ignore setting this 
> register.
> +     */
> +    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..c72c7bb9bb 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 +193,14 @@ 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 of the IAPC_BOOT_ARCH register indicates i8042 
> presence
> +     * or equivalent micro controller. See table 5-10 of APCI spec version 
> 2.0
> +     * (the earliest acpi revision that supports this).

 /* APCI spec version 2.0, Table 5-10 */

is sufficient, the rest could be read from spec/

> +     */
> +    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 68ca7e7fc2..4bc72b1672 100644
> --- a/hw/i386/acpi-microvm.c
> +++ b/hw/i386/acpi-microvm.c
> @@ -31,6 +31,7 @@
>  #include "hw/acpi/generic_event_device.h"
>  #include "hw/acpi/utils.h"
>  #include "hw/acpi/erst.h"
> +#include "hw/input/i8042.h"
>  #include "hw/i386/fw_cfg.h"
>  #include "hw/i386/microvm.h"
>  #include "hw/pci/pci.h"
> @@ -189,6 +190,14 @@ static void acpi_build_microvm(AcpiBuildTables *tables,
>          .reset_val = ACPI_GED_RESET_VALUE,
>      };
>  
> +    /*
> +     * second bit of 16 of the IAPC_BOOT_ARCH register indicates i8042 
> presence
> +     * 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 = object_resolve_path_type("", TYPE_I8042, NULL) ?
> +                            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 */
>  
>      /*