Re: [Qemu-devel] [PATCH 2/2] pc: acpi-build: make linker & RSDP tables dynamic

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, Dec 10, 2014 at 04:06:56PM +0000, Igor Mammedov wrote:
> linker and RSDP tables are build only once, so if later
> during rebuild sizes of other ACPI tables change
> pointers will be patched incorrectly due to wrong
> offsets.
> 
> To fix it rebuild linker and RSDP tables along with
> the rest of ACPI tables so that they would have correct
> offsets.
> 
> Here is a simple reproducer:
>  1: hotplug bridge using command:
>      device_add pci-bridge,chassis_nr=1
>  2: reset system from monitor:
>      system_reset
> 
> As result pointers to ACPI tables are not correct
> and guest can't read/parse ACPI tables.
> Windows guests just refuse to boot and
> Linux guests are more resilient and try to boot without
> ACPI, sometimes successfully.
> 
> PS:
>  keep brokenness in 2.2 and older machine types for the sake
>  of migration
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>

I'd like to fix 2.2 as well.

Why does adding bridge in this way cause tables to
be resized?
I think this is a root-cause that should be fixed.

> ---
> Tested backwards migration from QEMU 2.3 to 2.2 with
> pc-i440fx-2.2 machine type
> 
>  hw/i386/acpi-build.c | 30 +++++++++++++++++++++++-------
>  hw/i386/pc_piix.c    |  3 +++
>  hw/i386/pc_q35.c     |  3 +++
>  include/hw/i386/pc.h |  1 +
>  4 files changed, 30 insertions(+), 7 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index b37a397..4d2452d 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1509,6 +1509,10 @@ struct AcpiBuildState {
>      /* Copy of table in RAM (for patching). */
>      ram_addr_t table_ram;
>      uint32_t table_size;
> +    ram_addr_t linker_ram;
> +    uint32_t linker_size;
> +    ram_addr_t rsdp_ram;
> +    uint32_t rsdp_size;
>      /* Is table patched? */
>      uint8_t patched;
>      PcGuestInfo *guest_info;
> @@ -1714,6 +1718,10 @@ static void acpi_build_update(void *build_opaque, uint32_t offset)
>      assert(acpi_data_len(tables.table_data) == build_state->table_size);
>      memcpy(qemu_get_ram_ptr(build_state->table_ram), tables.table_data->data,
>             build_state->table_size);
> +    memcpy(qemu_get_ram_ptr(build_state->linker_ram), tables.linker->data,
> +           build_state->linker_size);
> +    memcpy(qemu_get_ram_ptr(build_state->rsdp_ram), tables.rsdp->data,
> +           build_state->rsdp_size);
>  
>      cpu_physical_memory_set_dirty_range_nocode(build_state->table_ram,
>                                                 build_state->table_size);
> @@ -1779,17 +1787,25 @@ void acpi_setup(PcGuestInfo *guest_info)
>      assert(build_state->table_ram != RAM_ADDR_MAX);
>      build_state->table_size = acpi_data_len(tables.table_data);
>  
> -    acpi_add_rom_blob(NULL, tables.linker, "etc/table-loader");
> +    build_state->linker_ram = acpi_add_rom_blob(build_state, tables.linker,
> +                                                "etc/table-loader");
> +    build_state->linker_size = acpi_data_len(tables.linker);
>  
>      fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_TPMLOG_FILE,
>                      tables.tcpalog->data, acpi_data_len(tables.tcpalog));
>  
> -    /*
> -     * RSDP is small so it's easy to keep it immutable, no need to
> -     * bother with ROM blobs.
> -     */
> -    fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_RSDP_FILE,
> -                    tables.rsdp->data, acpi_data_len(tables.rsdp));
> +    if (guest_info->has_imutable_rsdp) {
> +        /*
> +         * RSDP is small so it's easy to keep it immutable, no need to
> +         * bother with ROM blobs.
> +         */
> +        fw_cfg_add_file(guest_info->fw_cfg, ACPI_BUILD_RSDP_FILE,
> +                        tables.rsdp->data, acpi_data_len(tables.rsdp));
> +    } else {
> +        build_state->rsdp_ram = acpi_add_rom_blob(build_state, tables.rsdp,
> +                                                  ACPI_BUILD_RSDP_FILE);
> +        build_state->rsdp_size = acpi_data_len(tables.rsdp);
> +    }
>  
>      qemu_register_reset(acpi_build_reset, build_state);
>      acpi_build_reset(build_state);
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 685fa54..69d4de2 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -60,6 +60,7 @@ static const int ide_iobase2[MAX_IDE_BUS] = { 0x3f6, 0x376 };
>  static const int ide_irq[MAX_IDE_BUS] = { 14, 15 };
>  
>  static bool has_acpi_build = true;
> +static bool has_imutable_rsdp;
>  static int legacy_acpi_table_size;
>  static bool smbios_defaults = true;
>  static bool smbios_legacy_mode;
> @@ -168,6 +169,7 @@ static void pc_init1(MachineState *machine,
>  
>      guest_info->isapc_ram_fw = !pci_enabled;
>      guest_info->has_reserved_memory = has_reserved_memory;
> +    guest_info->has_imutable_rsdp = has_imutable_rsdp;
>  
>      if (smbios_defaults) {
>          MachineClass *mc = MACHINE_GET_CLASS(machine);
> @@ -310,6 +312,7 @@ static void pc_init_pci(MachineState *machine)
>  
>  static void pc_compat_2_2(MachineState *machine)
>  {
> +    has_imutable_rsdp = true;
>  }
>  
>  static void pc_compat_2_1(MachineState *machine)
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 121f620..6bbc100 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -50,6 +50,7 @@
>  #define MAX_SATA_PORTS     6
>  
>  static bool has_acpi_build = true;
> +static bool has_imutable_rsdp;
>  static bool smbios_defaults = true;
>  static bool smbios_legacy_mode;
>  static bool smbios_uuid_encoded = true;
> @@ -154,6 +155,7 @@ static void pc_q35_init(MachineState *machine)
>      guest_info->isapc_ram_fw = false;
>      guest_info->has_acpi_build = has_acpi_build;
>      guest_info->has_reserved_memory = has_reserved_memory;
> +    guest_info->has_imutable_rsdp = has_imutable_rsdp;
>  
>      /* Migration was not supported in 2.0 for Q35, so do not bother
>       * with this hack (see hw/i386/acpi-build.c).
> @@ -289,6 +291,7 @@ static void pc_q35_init(MachineState *machine)
>  
>  static void pc_compat_2_2(MachineState *machine)
>  {
> +    has_imutable_rsdp = true;
>  }
>  
>  static void pc_compat_2_1(MachineState *machine)
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 69d9cf8..acc95ea 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -104,6 +104,7 @@ struct PcGuestInfo {
>      int legacy_acpi_table_size;
>      bool has_acpi_build;
>      bool has_reserved_memory;
> +    bool has_imutable_rsdp;
>  };
>  
>  /* parallel.c */
> -- 
> 1.8.3.1