Re: [PATCH v4 01/14] acpi/ghes: prepare to change the way HEST offsets are calculated

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 21 Feb 2025 15:35:10 +0100
Mauro Carvalho Chehab <mchehab+huawei@kernel.org> wrote:

> Add a new ags flag to change the way HEST offsets are calculated.
> Currently, offsets needed to store ACPI HEST offsets and read ack
> are calculated based on a previous knowledge from the logic
> which creates the HEST table.
> 
> Such logic is not generic, not allowing to easily add more HEST
> entries nor replicates what OSPM does.
> 
> As the next patches will be adding a more generic logic, add a
> new use_hest_addr, set to false, in preparation for such changes.
> 
> Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
> ---
>  hw/acpi/ghes.c           | 46 ++++++++++++++++++++++++----------------
>  hw/arm/virt-acpi-build.c | 15 ++++++++++---
>  include/hw/acpi/ghes.h   | 14 ++++++++++--
>  3 files changed, 52 insertions(+), 23 deletions(-)
> 
> diff --git a/hw/acpi/ghes.c b/hw/acpi/ghes.c
> index b709c177cdea..e49a03fdb94e 100644
> --- a/hw/acpi/ghes.c
> +++ b/hw/acpi/ghes.c
> @@ -206,7 +206,8 @@ ghes_gen_err_data_uncorrectable_recoverable(GArray *block,
>   * Initialize "etc/hardware_errors" and "etc/hardware_errors_addr" fw_cfg blobs.
>   * See docs/specs/acpi_hest_ghes.rst for blobs format.
>   */
> -static void build_ghes_error_table(GArray *hardware_errors, BIOSLinker *linker)
> +static void build_ghes_error_table(AcpiGhesState *ags, GArray *hardware_errors,
> +                                   BIOSLinker *linker)
>  {
>      int i, error_status_block_offset;
>  
> @@ -251,13 +252,15 @@ static void build_ghes_error_table(GArray *hardware_errors, BIOSLinker *linker)
>                                         i * ACPI_GHES_MAX_RAW_DATA_LENGTH);
>      }
>  
> -    /*
> -     * tell firmware to write hardware_errors GPA into
> -     * hardware_errors_addr fw_cfg, once the former has been initialized.
> -     */
> -    bios_linker_loader_write_pointer(linker, ACPI_HW_ERROR_ADDR_FW_CFG_FILE, 0,
> -                                     sizeof(uint64_t),
> -                                     ACPI_HW_ERROR_FW_CFG_FILE, 0);
> +    if (!ags->use_hest_addr) {
> +        /*
> +         * Tell firmware to write hardware_errors GPA into
> +         * hardware_errors_addr fw_cfg, once the former has been initialized.
> +         */
> +        bios_linker_loader_write_pointer(linker, ACPI_HW_ERROR_ADDR_FW_CFG_FILE,
> +                                         0, sizeof(uint64_t),
> +                                         ACPI_HW_ERROR_FW_CFG_FILE, 0);
> +    }
>  }
>  
>  /* Build Generic Hardware Error Source version 2 (GHESv2) */
> @@ -331,14 +334,15 @@ static void build_ghes_v2(GArray *table_data,
>  }
>  
>  /* Build Hardware Error Source Table */
> -void acpi_build_hest(GArray *table_data, GArray *hardware_errors,
> +void acpi_build_hest(AcpiGhesState *ags, GArray *table_data,
> +                     GArray *hardware_errors,
>                       BIOSLinker *linker,
>                       const char *oem_id, const char *oem_table_id)
>  {
>      AcpiTable table = { .sig = "HEST", .rev = 1,
>                          .oem_id = oem_id, .oem_table_id = oem_table_id };
>  
> -    build_ghes_error_table(hardware_errors, linker);
> +    build_ghes_error_table(ags, hardware_errors, linker);
>  
>      acpi_table_begin(&table, table_data);
>  
> @@ -357,11 +361,11 @@ void acpi_ghes_add_fw_cfg(AcpiGhesState *ags, FWCfgState *s,
>      fw_cfg_add_file(s, ACPI_HW_ERROR_FW_CFG_FILE, hardware_error->data,
>                      hardware_error->len);
>  
> -    /* Create a read-write fw_cfg file for Address */
> -    fw_cfg_add_file_callback(s, ACPI_HW_ERROR_ADDR_FW_CFG_FILE, NULL, NULL,
> -        NULL, &(ags->hw_error_le), sizeof(ags->hw_error_le), false);
> -
> -    ags->present = true;
> +    if (!ags->use_hest_addr) {
> +        /* Create a read-write fw_cfg file for Address */
> +        fw_cfg_add_file_callback(s, ACPI_HW_ERROR_ADDR_FW_CFG_FILE, NULL, NULL,
> +            NULL, &(ags->hw_error_le), sizeof(ags->hw_error_le), false);
> +    }
>  }
>  
>  static void get_hw_error_offsets(uint64_t ghes_addr,
> @@ -411,8 +415,11 @@ void ghes_record_cper_errors(const void *cper, size_t len,
>      ags = &acpi_ged_state->ghes_state;
>  
>      assert(ACPI_GHES_ERROR_SOURCE_COUNT == 1);
> -    get_hw_error_offsets(le64_to_cpu(ags->hw_error_le),
> -                         &cper_addr, &read_ack_register_addr);
> +
> +    if (!ags->use_hest_addr) {
> +        get_hw_error_offsets(le64_to_cpu(ags->hw_error_le),
> +                             &cper_addr, &read_ack_register_addr);
> +    }
>  
>      if (!cper_addr) {
>          error_setg(errp, "can not find Generic Error Status Block");
> @@ -494,5 +501,8 @@ bool acpi_ghes_present(void)
>          return false;
>      }
>      ags = &acpi_ged_state->ghes_state;
> -    return ags->present;
> +    if (!ags->hw_error_le)
> +        return false;
> +
> +    return true;
>  }
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 3ac8f8e17861..8ab8d11b6536 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -946,9 +946,18 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
>      build_dbg2(tables_blob, tables->linker, vms);
>  
>      if (vms->ras) {
> -        acpi_add_table(table_offsets, tables_blob);
> -        acpi_build_hest(tables_blob, tables->hardware_errors, tables->linker,
> -                        vms->oem_id, vms->oem_table_id);
> +        AcpiGedState *acpi_ged_state;
> +        AcpiGhesState *ags;
> +
> +        acpi_ged_state = ACPI_GED(object_resolve_path_type("", TYPE_ACPI_GED,
                            ^^^ will explode if object_resolve_path_type() returns NULL
> +                                                       NULL));

it's also expensive load-wise.
You have access to vms with ged pointer here, use that
(search for 'acpi_ged_state = ACPI_GED' example)

                            

> +        if (acpi_ged_state) {

                hence, this check is not really needed,
                we have to have GED at this point or abort

                earlier code that instantiates GED should take care of
                cleanly exiting if it failed to create GED so we would never get
                to missing GED here


> +            ags = &acpi_ged_state->ghes_state;
> +
> +            acpi_add_table(table_offsets, tables_blob);
> +            acpi_build_hest(ags, tables_blob, tables->hardware_errors,
> +                            tables->linker, vms->oem_id, vms->oem_table_id);
> +        }
>      }
>  
>      if (ms->numa_state->num_nodes > 0) {
> diff --git a/include/hw/acpi/ghes.h b/include/hw/acpi/ghes.h
> index 39619a2457cb..a3d62b96584f 100644
> --- a/include/hw/acpi/ghes.h
> +++ b/include/hw/acpi/ghes.h
> @@ -64,12 +64,22 @@ enum {
>      ACPI_GHES_ERROR_SOURCE_COUNT
>  };
>  
> +/*
> + * AcpiGhesState stores an offset that will be used to fill HEST entries.
> + *
> + * When use_hest_addr is false, the stored offset is placed at hw_error_le,
> + * meaning an offset from the etc/hardware_errors firmware address. This
> + * is the default on QEMU 9.x.
> + *
> + * An offset value equal to zero means that GHES is not present.
> + */
>  typedef struct AcpiGhesState {
>      uint64_t hw_error_le;
> -    bool present; /* True if GHES is present at all on this board */
> +    bool use_hest_addr;         /* Currently, always false */
>  } AcpiGhesState;
>  
> -void acpi_build_hest(GArray *table_data, GArray *hardware_errors,
> +void acpi_build_hest(AcpiGhesState *ags, GArray *table_data,
> +                     GArray *hardware_errors,
>                       BIOSLinker *linker,
>                       const char *oem_id, const char *oem_table_id);
>  void acpi_ghes_add_fw_cfg(AcpiGhesState *vms, FWCfgState *s,