Re: [Qemu-devel] [PATCH v2 2/5] pci: store PCI hole ranges in guestinfo structure

[Laszlo Ersek]

I can't offer any opinion about the values you put into w32 and w64, but I have 
some remarks.

First, please consider passing -O/path/to/some/order_file to git-format-patch, 
so that .h files show up at the top of each patch.

On 05/30/13 13:07, Michael S. Tsirkin wrote:
> Will be used to pass hole ranges to guests.
> 
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  hw/i386/pc.c              | 39 ++++++++++++++++++++++++++++++++++++++-
>  hw/i386/pc_piix.c         | 14 +++++++++++++-
>  hw/i386/pc_q35.c          |  6 +++++-
>  hw/pci-host/q35.c         |  4 ++++
>  include/hw/i386/pc.h      | 19 ++++++++++++++++++-
>  include/hw/pci-host/q35.h |  2 ++
>  include/qemu/typedefs.h   |  1 +
>  7 files changed, 81 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 4844a6b..c233161 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -978,6 +978,41 @@ void pc_cpus_init(const char *cpu_model, DeviceState 
> *icc_bridge)
>      }
>  }
>  
> +typedef struct PcGuestInfoState {
> +    PcGuestInfo info;
> +    Notifier machine_done;
> +} PcGuestInfoState;
> +
> +static
> +void pc_guest_info_machine_done(Notifier *notifier, void *data)
> +{
> +    PcGuestInfoState *guest_info_state = container_of(notifier,
> +                                                      PcGuestInfoState,
> +                                                      machine_done);
> +}
> +
> +PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
> +                                ram_addr_t above_4g_mem_size)
> +{
> +    PcGuestInfoState *guest_info_state = g_malloc0(sizeof *guest_info_state);
> +    PcGuestInfo *guest_info = &guest_info_state->info;
> +
> +    guest_info->pci_info.w32.end = IO_APIC_DEFAULT_ADDRESS;
> +    if (sizeof(hwaddr) == 4) {
> +        guest_info->pci_info.w64.begin = 0;
> +        guest_info->pci_info.w64.end = 0;
> +    } else {
> +        guest_info->pci_info.w64.begin = 0x100000000ULL + above_4g_mem_size;
> +        guest_info->pci_info.w64.end =  guest_info->pci_info.w64.begin +
> +            (0x1ULL << 62);
> +        assert(guest_info->pci_info.w64.begin <= 
> guest_info->pci_info.w64.end);
> +    }
> +
> +    guest_info_state->machine_done.notify = pc_guest_info_machine_done;
> +    qemu_add_machine_init_done_notifier(&guest_info_state->machine_done);
> +    return guest_info;
> +}
> +
>  void pc_acpi_init(const char *default_dsdt)
>  {
>      char *filename;
> @@ -1019,7 +1054,8 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>                             ram_addr_t below_4g_mem_size,
>                             ram_addr_t above_4g_mem_size,
>                             MemoryRegion *rom_memory,
> -                           MemoryRegion **ram_memory)
> +                           MemoryRegion **ram_memory,
> +                           PcGuestInfo *guest_info)
>  {
>      int linux_boot, i;
>      MemoryRegion *ram, *option_rom_mr;
> @@ -1071,6 +1107,7 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>      for (i = 0; i < nb_option_roms; i++) {
>          rom_add_option(option_rom[i].name, option_rom[i].bootindex);
>      }
> +    guest_info->fw_cfg = fw_cfg;
>      return fw_cfg;
>  }

I find this suboptimal style, ie. passing "guest_info" to pc_memory_init() just 
so that pc_memory_init() can set guest_info->fw_cfg to fw_cfg, when 
pc_memory_init() returns fw_cfg anyway.

More "philosophically":

> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index b4c8a74..1bf5219 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -9,8 +9,20 @@
>  #include "net/net.h"
>  #include "hw/i386/ioapic.h"
>  
> +#include "qemu/range.h"
> +
>  /* PC-style peripherals (also used by other machines).  */
>  
> +typedef struct PcPciInfo {
> +    Range w32;
> +    Range w64;
> +} PcPciInfo;
> +
> +struct PcGuestInfo {
> +    PcPciInfo pci_info;
> +    FWCfgState *fw_cfg;
> +};

Are you sure you need a private link to the global fw_cfg object? The pvpanic 
series added a global lookup possibility in commit 10a584b2 
(object_resolve_path()).

Anyway these are just subjective style notes.

> +
>  /* parallel.c */
>  static inline bool parallel_init(ISABus *bus, int index, CharDriverState 
> *chr)
>  {
> @@ -80,6 +92,10 @@ void pc_acpi_smi_interrupt(void *opaque, int irq, int 
> level);
>  void pc_cpus_init(const char *cpu_model, DeviceState *icc_bridge);
>  void pc_hot_add_cpu(const int64_t id, Error **errp);
>  void pc_acpi_init(const char *default_dsdt);
> +
> +PcGuestInfo *pc_guest_info_init(ram_addr_t below_4g_mem_size,
> +                                ram_addr_t above_4g_mem_size);
> +
>  FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>                             const char *kernel_filename,
>                             const char *kernel_cmdline,
> @@ -87,7 +103,8 @@ FWCfgState *pc_memory_init(MemoryRegion *system_memory,
>                             ram_addr_t below_4g_mem_size,
>                             ram_addr_t above_4g_mem_size,
>                             MemoryRegion *rom_memory,
> -                           MemoryRegion **ram_memory);
> +                           MemoryRegion **ram_memory,
> +                           PcGuestInfo *guest_info);
>  qemu_irq *pc_allocate_cpu_irq(void);
>  DeviceState *pc_vga_init(ISABus *isa_bus, PCIBus *pci_bus);
>  void pc_basic_device_init(ISABus *isa_bus, qemu_irq *gsi,

Going forward:

>  
> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> index d547548..eaff0b6 100644
> --- a/hw/i386/pc_piix.c
> +++ b/hw/i386/pc_piix.c
> @@ -90,6 +90,7 @@ static void pc_init1(MemoryRegion *system_memory,
>      MemoryRegion *rom_memory;
>      DeviceState *icc_bridge;
>      FWCfgState *fw_cfg = NULL;
> +    PcGuestInfo *guest_info;
>  
>      icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
>      object_property_add_child(qdev_get_machine(), "icc-bridge",
> @@ -119,12 +120,23 @@ static void pc_init1(MemoryRegion *system_memory,
>          rom_memory = system_memory;
>      }
>  
> +    guest_info = pc_guest_info_init(below_4g_mem_size, above_4g_mem_size);
> +
> +    /* Set PCI window size the way seabios has always done it. */
> +    /* TODO: consider just starting at below_4g_mem_size */
> +    if (ram_size <= 0x80000000)
> +        guest_info->pci_info.w32.begin = 0x80000000;
> +    else if (ram_size <= 0xc0000000)
> +        guest_info->pci_info.w32.begin = 0xc0000000;
> +    else
> +        guest_info->pci_info.w32.begin = 0xe0000000;
> +
>      /* allocate ram and load rom/bios */
>      if (!xen_enabled()) {
>          fw_cfg = pc_memory_init(system_memory,
>                         kernel_filename, kernel_cmdline, initrd_filename,
>                         below_4g_mem_size, above_4g_mem_size,
> -                       rom_memory, &ram_memory);
> +                       rom_memory, &ram_memory, guest_info);
>      }
>  
>      gsi_state = g_malloc0(sizeof(*gsi_state));

On PIIX you *almost* leak the guest_info structure at once; the only link to it 
is the machine-done-notifier registered in pc_guest_info_init(). Is this 
intended? (I guess a later patch in the series will change this.)

> diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> index 7888dfe..32d6357 100644
> --- a/hw/i386/pc_q35.c
> +++ b/hw/i386/pc_q35.c
> @@ -77,6 +77,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>      ICH9LPCState *ich9_lpc;
>      PCIDevice *ahci;
>      DeviceState *icc_bridge;
> +    PcGuestInfo *guest_info;
>  
>      icc_bridge = qdev_create(NULL, TYPE_ICC_BRIDGE);
>      object_property_add_child(qdev_get_machine(), "icc-bridge",
> @@ -105,11 +106,13 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>          rom_memory = get_system_memory();
>      }
>  
> +    guest_info = pc_guest_info_init(below_4g_mem_size, above_4g_mem_size);
> +
>      /* allocate ram and load rom/bios */
>      if (!xen_enabled()) {
>          pc_memory_init(get_system_memory(), kernel_filename, kernel_cmdline,
>                         initrd_filename, below_4g_mem_size, above_4g_mem_size,
> -                       rom_memory, &ram_memory);
> +                       rom_memory, &ram_memory, guest_info);
>      }
>  
>      /* irq lines */
> @@ -131,6 +134,7 @@ static void pc_q35_init(QEMUMachineInitArgs *args)
>      q35_host->mch.address_space_io = get_system_io();
>      q35_host->mch.below_4g_mem_size = below_4g_mem_size;
>      q35_host->mch.above_4g_mem_size = above_4g_mem_size;
> +    q35_host->mch.guest_info = guest_info;
>      /* pci */
>      qdev_init_nofail(DEVICE(q35_host));
>      host_bus = q35_host->host.pci.bus;

OK, a direct (owner) link is established here; which gives birth to the next 
question:

> diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
> index 24df6b5..63c64dd 100644
> --- a/hw/pci-host/q35.c
> +++ b/hw/pci-host/q35.c
> @@ -244,6 +244,10 @@ static int mch_init(PCIDevice *d)
>      hwaddr pci_hole64_size;
>      MCHPCIState *mch = MCH_PCI_DEVICE(d);
>  
> +    /* Leave enough space for the biggest MCFG BAR */
> +    mch->guest_info->pci_info.w32.begin = MCH_HOST_BRIDGE_PCIEXBAR_DEFAULT +
> +        MCH_HOST_BRIDGE_PCIEXBAR_MAX;
> +
>      /* setup pci memory regions */
>      memory_region_init_alias(&mch->pci_hole, "pci-hole",
>                               mch->pci_address_space,


> diff --git a/include/hw/pci-host/q35.h b/include/hw/pci-host/q35.h
> index e182c82..b083831 100644
> --- a/include/hw/pci-host/q35.h
> +++ b/include/hw/pci-host/q35.h
> @@ -55,6 +55,7 @@ typedef struct MCHPCIState {
>      uint8_t smm_enabled;
>      ram_addr_t below_4g_mem_size;
>      ram_addr_t above_4g_mem_size;
> +    PcGuestInfo *guest_info;
>  } MCHPCIState;

... how does this relate to migration? (I'm not suggesting anything, I'm just 
curious.)

Thanks,
Laszlo