Re: [Qemu-devel] [PATCH 03/27] pc: add 'etc/reserved-memory-end' fw_cfg interface for SeaBIOS

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

On Thu, Nov 21, 2013 at 03:38:24AM +0100, Igor Mammedov wrote:
> 'etc/reserved-memory-end' will allow QEMU to tell BIOS where PCI
> BARs mapping could safely start in high memory.
> 
> Allowing BIOS to start mapping 64-bit PCI BARs at address where it
> wouldn't conflict with other mappings QEMU might place before it.
> 
> That permits QEMU to reserve extra address space before
> 64-bit PCI hole for memory hotplug.
> 
> Signed-off-by: Igor Mammedov <imammedo@redhat.com>
> ---
> v2:
>    * disable 'etc/reserved-memory-end' for 1.7 and older machine types
> ---
>  hw/i386/pc.c         |   27 +++++++++++++++++++++++++--
>  hw/i386/pc_piix.c    |    1 +
>  hw/i386/pc_q35.c     |    1 +
>  hw/pci-host/piix.c   |    3 ++-
>  hw/pci-host/q35.c    |    3 ++-
>  include/hw/i386/pc.h |   11 +++++++++--
>  6 files changed, 40 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 6c82ada..ba82c67 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -1094,14 +1094,37 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
>  }
>  
>  /* setup pci memory address space mapping into system address space */
> -void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> -                            MemoryRegion *pci_address_space)
> +void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
> +                                MemoryRegion *pci_address_space,
> +                                uint64_t reserved_memory_end)
>  {
>      /* Set to lower priority than RAM */
>      memory_region_add_subregion_overlap(system_memory, 0x0,
>                                          pci_address_space, -1);
>  }
>  
> +static
> +void pc_pci_as_mapping_init_1_8(Object *owner, MemoryRegion *system_memory,
> +                                MemoryRegion *pci_address_space,
> +                                uint64_t reserved_memory_end)
> +{
> +    uint64_t *val;
> +    FWCfgState *fw_cfg = fw_cfg_find();
> +    g_assert(fw_cfg);
> +    /*
> +     *  Align address at 1G, this makes sure it can be exactly covered
> +     *  with a PAT entry even when using huge pages.
> +     */
> +    val = g_malloc(sizeof(*val));
> +    *val = cpu_to_le64(ROUND_UP(reserved_memory_end, 0x1ULL << 30));
> +    fw_cfg_add_file(fw_cfg, "etc/reserved-memory-end", val, sizeof(*val));
> +
> +    pc_pci_as_mapping_init_1_7(owner, system_memory, pci_address_space,
> +                               reserved_memory_end);
> +}
> +
> +pc_pci_as_mapping_init_fn pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_8;
> +
>  void pc_acpi_init(const char *default_dsdt)
>  {
>      char *filename;
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index 36f2495..e1fe85a 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -249,6 +249,7 @@ static void pc_init_pci(QEMUMachineInitArgs *args)
>  static void pc_compat_1_7(QEMUMachineInitArgs *args)
>  {
>      smbios_type1_defaults = false;
> +    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
>  }
>  
>  static void pc_compat_1_6(QEMUMachineInitArgs *args)
> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 50ca458..5525465 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -233,6 +233,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>  static void pc_compat_1_7(QEMUMachineInitArgs *args)
>  {
>      smbios_type1_defaults = false;
> +    pc_pci_as_mapping_init = pc_pci_as_mapping_init_1_7;
>  }
>  
>  static void pc_compat_1_6(QEMUMachineInitArgs *args)

I don't much like this: why not use a global flag like we do
for other properties?

Also, 1_8 should be replaced with 2_0 now.

> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> index 63be7f6..615ab0d 100644
> --- a/hw/pci-host/piix.c
> +++ b/hw/pci-host/piix.c
> @@ -352,7 +352,8 @@ PCIBus *i440fx_init(PCII440FXState **pi440fx_state,
>  
>      /* setup pci memory mapping */
>      pc_pci_as_mapping_init(OBJECT(f), f->system_memory,
> -                           f->pci_address_space);
> +                           f->pci_address_space,
> +                           0x100000000ULL + above_4g_mem_size);
>  
>      memory_region_init_alias(&f->smram_region, OBJECT(d), "smram-region",
>                               f->pci_address_space, 0xa0000, 0x20000);
> diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> index 81c8240..6e28418 100644
> --- a/hw/pci-host/q35.c
> +++ b/hw/pci-host/q35.c
> @@ -359,7 +359,8 @@ static int mch_init(PCIDevice *d)
>  
>      /* setup pci memory mapping */
>      pc_pci_as_mapping_init(OBJECT(mch), mch->system_memory,
> -                           mch->pci_address_space);
> +                           mch->pci_address_space,
> +                           0x100000000ULL + mch->above_4g_mem_size);
>  
>      /* smram */
>      cpu_smm_register(&mch_set_smm, mch);
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 9af09d3..c4e8048 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -129,8 +129,15 @@ PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
>  #define DEFAULT_PCI_HOLE64_SIZE (~0x0ULL)
>  
>  
> -void pc_pci_as_mapping_init(Object *owner, MemoryRegion *system_memory,
> -                            MemoryRegion *pci_address_space);
> +typedef
> +void (*pc_pci_as_mapping_init_fn)(Object *owner, MemoryRegion *system_memory,
> +                                  MemoryRegion *pci_address_space,
> +                                  uint64_t reserved_memory_end);
> +extern pc_pci_as_mapping_init_fn pc_pci_as_mapping_init;
> +
> +void pc_pci_as_mapping_init_1_7(Object *owner, MemoryRegion *system_memory,
> +                                MemoryRegion *pci_address_space,
> +                                uint64_t reserved_memory_end);
>  
>  FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>                             const char *kernel_filename,
> -- 
> 1.7.1