Re: [PATCH 2/2] add maximum combined fw size as machine configuration option

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Erich,

On 9/18/20 6:23 AM, Erich Mcmillan wrote:
> From: Erich McMillan <erich.mcmillan@hp.com>

Description/rationale?

> 
> Signed-off-by: Erich McMillan <erich.mcmillan@hp.com>
> ---
>  hw/i386/pc.c         | 40 ++++++++++++++++++++++++++++++++++++++++
>  hw/i386/pc_sysfw.c   | 13 ++-----------
>  include/hw/i386/pc.h | 22 ++++++++++++----------
>  3 files changed, 54 insertions(+), 21 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index d11daac..b304988 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1869,6 +1869,39 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
>      pcms->max_ram_below_4g = value;
>  }
>  
> +static void pc_machine_get_max_fw_size(Object *obj, Visitor *v,
> +                                             const char *name, void *opaque,
> +                                             Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +    uint64_t value = pcms->max_fw_size;
> +
> +    visit_type_size(v, name, &value, errp);
> +}
> +
> +static void pc_machine_set_max_fw_size(Object *obj, Visitor *v,
> +                                             const char *name, void *opaque,
> +                                             Error **errp)
> +{
> +    PCMachineState *pcms = PC_MACHINE(obj);
> +    Error *error = NULL;
> +    uint64_t value;
> +
> +    visit_type_size(v, name, &value, &error);
> +    if (error) {
> +        error_propagate(errp, error);
> +        return;
> +    }
> +
> +    if (value > 16 * MiB) {
> +        warn_report("User specifed max allowed firmware size %" PRIu64 " is greater than 16MiB,"
> +                    "if combined firwmare size exceeds 16MiB system may not boot,"

Typos "specified", "firmware".

> +                    "or experience intermittent stability issues.", value);
> +    }
> +
> +    pcms->max_fw_size = value;
> +}
> +
>  static void pc_machine_initfn(Object *obj)
>  {
>      PCMachineState *pcms = PC_MACHINE(obj);
> @@ -1884,6 +1917,7 @@ static void pc_machine_initfn(Object *obj)
>      pcms->smbus_enabled = true;
>      pcms->sata_enabled = true;
>      pcms->pit_enabled = true;
> +    pcms->max_fw_size = 8 * MiB;

I'm very confused by pc_system_flash_map()... Why not check
that no pflash exceeds 8MiB? Then 2 combined would be always
<16MiB.

>  
>      pc_system_flash_create(pcms);
>      pcms->pcspk = isa_new(TYPE_PC_SPEAKER);
> @@ -2004,6 +2038,12 @@ static void pc_machine_class_init(ObjectClass *oc, void *data)
>  
>      object_class_property_add_bool(oc, PC_MACHINE_PIT,
>          pc_machine_get_pit, pc_machine_set_pit);
> +
> +    object_class_property_add(oc, PC_MACHINE_MAX_FW_SIZE, "size",
> +        pc_machine_get_max_fw_size, pc_machine_set_max_fw_size,
> +        NULL, NULL);
> +    object_class_property_set_description(oc, PC_MACHINE_MAX_FW_SIZE,
> +        "Maximum combined firmware size");
>  }
>  
>  static const TypeInfo pc_machine_info = {
> diff --git a/hw/i386/pc_sysfw.c b/hw/i386/pc_sysfw.c
> index b6c0822..22450ba 100644
> --- a/hw/i386/pc_sysfw.c
> +++ b/hw/i386/pc_sysfw.c
> @@ -39,15 +39,6 @@
>  #include "hw/block/flash.h"
>  #include "sysemu/kvm.h"
>  
> -/*
> - * We don't have a theoretically justifiable exact lower bound on the base
> - * address of any flash mapping. In practice, the IO-APIC MMIO range is
> - * [0xFEE00000..0xFEE01000] -- see IO_APIC_DEFAULT_ADDRESS --, leaving free
> - * only 18MB-4KB below 4G. For now, restrict the cumulative mapping to 8MB in
> - * size.
> - */
> -#define FLASH_SIZE_LIMIT (8 * MiB)
> -
>  #define FLASH_SECTOR_SIZE 4096
>  
>  static void pc_isa_bios_init(MemoryRegion *rom_memory,
> @@ -182,10 +173,10 @@ static void pc_system_flash_map(PCMachineState *pcms,
>          }
>          if ((hwaddr)size != size
>              || total_size > HWADDR_MAX - size
> -            || total_size + size > FLASH_SIZE_LIMIT) {
> +            || total_size + size > pcms->max_fw_size) {
>              error_report("combined size of system firmware exceeds "
>                           "%" PRIu64 " bytes",
> -                         FLASH_SIZE_LIMIT);
> +                         pcms->max_fw_size);
>              exit(1);
>          }
>  
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index fe52e16..cae213d 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -39,10 +39,11 @@ struct PCMachineState {
>      uint64_t max_ram_below_4g;
>      OnOffAuto vmport;
>  
> -    bool acpi_build_enabled;
> -    bool smbus_enabled;
> -    bool sata_enabled;
> -    bool pit_enabled;
> +    bool     acpi_build_enabled;
> +    bool     smbus_enabled;
> +    bool     sata_enabled;
> +    bool     pit_enabled;
> +    uint64_t max_fw_size;
>  
>      /* NUMA information: */
>      uint64_t numa_nodes;
> @@ -52,13 +53,14 @@ struct PCMachineState {
>      hwaddr memhp_io_base;
>  };
>  
> -#define PC_MACHINE_ACPI_DEVICE_PROP "acpi-device"
> -#define PC_MACHINE_MAX_RAM_BELOW_4G "max-ram-below-4g"
> +#define PC_MACHINE_ACPI_DEVICE_PROP   "acpi-device"
> +#define PC_MACHINE_MAX_RAM_BELOW_4G   "max-ram-below-4g"
>  #define PC_MACHINE_DEVMEM_REGION_SIZE "device-memory-region-size"
> -#define PC_MACHINE_VMPORT           "vmport"
> -#define PC_MACHINE_SMBUS            "smbus"
> -#define PC_MACHINE_SATA             "sata"
> -#define PC_MACHINE_PIT              "pit"
> +#define PC_MACHINE_VMPORT             "vmport"
> +#define PC_MACHINE_SMBUS              "smbus"
> +#define PC_MACHINE_SATA               "sata"
> +#define PC_MACHINE_PIT                "pit"
> +#define PC_MACHINE_MAX_FW_SIZE        "max-fw-size"

Having the space alignment changes in a previous "sanitize"
patch would ease the review of this one.

>  
>  /**
>   * PCMachineClass:
>