Re: [PATCH 15/15] hw/i386/pc_piix: Move i440fx' realize near its qdev_new()

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 12 Jun 2023 16:51:55 +0200
Igor Mammedov <imammedo@redhat.com> wrote:

> On Sun, 11 Jun 2023 12:34:12 +0200
> Bernhard Beschow <shentey@gmail.com> wrote:
> 
> > I440FX realization is currently mixed with PIIX3 creation. Furthermore, it is
> > common practice to only set properties between a device's qdev_new() and
> > qdev_realize(). Clean up to resolve both issues.
> > 
> > Since I440FX spawns a PCI bus let's also move the pci_bus initialization there.
> > 
> > Note that when running `qemu-system-x86_64 -M pc -S` before and after this
> > patch, `info mtree` in the QEMU console doesn't show any differences except that
> > the ordering is different.
> > 
> > Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> > ---
> >  hw/i386/pc_piix.c | 57 ++++++++++++++++++++++++-----------------------
> >  1 file changed, 29 insertions(+), 28 deletions(-)
> > 
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index 22173b122b..23b9725c94 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -126,7 +126,6 @@ static void pc_init1(MachineState *machine,
> >      MemoryRegion *rom_memory;
> >      ram_addr_t lowmem;
> >      uint64_t hole64_size;
> > -    Object *i440fx_host;
> >  
> >      /*
> >       * Calculate ram split, for memory below and above 4G.  It's a bit
> > @@ -198,17 +197,43 @@ static void pc_init1(MachineState *machine,
> >      }
> >  
> >      if (pcmc->pci_enabled) {
> > +        Object *phb;
> > +
> >          pci_memory = g_new(MemoryRegion, 1);
> >          memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
> >          rom_memory = pci_memory;
> > -        i440fx_host = OBJECT(qdev_new(host_type));
> > -        hole64_size = object_property_get_uint(i440fx_host,
> > +
> > +        phb = OBJECT(qdev_new(host_type));
> > +        object_property_add_child(OBJECT(machine), "i440fx", phb);
> > +        object_property_set_link(phb, PCI_HOST_PROP_RAM_MEM,
> > +                                 OBJECT(ram_memory), &error_fatal);
> > +        object_property_set_link(phb, PCI_HOST_PROP_PCI_MEM,
> > +                                 OBJECT(pci_memory), &error_fatal);
> > +        object_property_set_link(phb, PCI_HOST_PROP_SYSTEM_MEM,
> > +                                 OBJECT(system_memory), &error_fatal);
> > +        object_property_set_link(phb, PCI_HOST_PROP_IO_MEM,
> > +                                 OBJECT(system_io), &error_fatal);
> > +        object_property_set_uint(phb, PCI_HOST_BELOW_4G_MEM_SIZE,
> > +                                 x86ms->below_4g_mem_size, &error_fatal);
> > +        object_property_set_uint(phb, PCI_HOST_ABOVE_4G_MEM_SIZE,
> > +                                 x86ms->above_4g_mem_size, &error_fatal);
> > +        object_property_set_str(phb, I440FX_HOST_PROP_PCI_TYPE, pci_type,
> > +                                &error_fatal);
> > +        sysbus_realize_and_unref(SYS_BUS_DEVICE(phb), &error_fatal);
> > +
> > +        pci_bus = PCI_BUS(qdev_get_child_bus(DEVICE(phb), "pci.0"));
> > +        pci_bus_map_irqs(pci_bus,
> > +                         xen_enabled() ? xen_pci_slot_get_pirq
> > +                                       : pc_pci_slot_get_pirq);
> > +        pcms->bus = pci_bus;
> > +
> > +        hole64_size = object_property_get_uint(phb,
> >                                                 PCI_HOST_PROP_PCI_HOLE64_SIZE,
> >                                                 &error_abort);  
> 
> before patch memory region links were set after the original
> regions were initialized by pc_memory_init(), but after this
> patch you 1st set links and only later pc_memory_init().
> I doesn't look to me as a safe thing to do.

or maybe it doesn't matter, but still I have hard time
convincing myself that it is so. 

> 
> >      } else {  
> 
> 
> >          pci_memory = NULL;
> >          rom_memory = system_memory;
> > -        i440fx_host = NULL;
> > +        pci_bus = NULL;
> >          hole64_size = 0;  
> 
> is it possible to turn these into initializers, and get rid of 
> 'else'  branch?
> 
> >      }
> >  
> > @@ -243,29 +268,6 @@ static void pc_init1(MachineState *machine,
> >          PIIX3State *piix3;
> >          PCIDevice *pci_dev;
> >  
> > -        object_property_add_child(OBJECT(machine), "i440fx", i440fx_host);
> > -        object_property_set_link(i440fx_host, PCI_HOST_PROP_RAM_MEM,
> > -                                 OBJECT(ram_memory), &error_fatal);
> > -        object_property_set_link(i440fx_host, PCI_HOST_PROP_PCI_MEM,
> > -                                 OBJECT(pci_memory), &error_fatal);
> > -        object_property_set_link(i440fx_host, PCI_HOST_PROP_SYSTEM_MEM,
> > -                                 OBJECT(system_memory), &error_fatal);
> > -        object_property_set_link(i440fx_host, PCI_HOST_PROP_IO_MEM,
> > -                                 OBJECT(system_io), &error_fatal);
> > -        object_property_set_uint(i440fx_host, PCI_HOST_BELOW_4G_MEM_SIZE,
> > -                                 x86ms->below_4g_mem_size, &error_fatal);
> > -        object_property_set_uint(i440fx_host, PCI_HOST_ABOVE_4G_MEM_SIZE,
> > -                                 x86ms->above_4g_mem_size, &error_fatal);
> > -        object_property_set_str(i440fx_host, I440FX_HOST_PROP_PCI_TYPE,
> > -                                pci_type, &error_fatal);
> > -        sysbus_realize_and_unref(SYS_BUS_DEVICE(i440fx_host), &error_fatal);
> > -
> > -        pci_bus = PCI_BUS(qdev_get_child_bus(DEVICE(i440fx_host), "pci.0"));
> > -        pci_bus_map_irqs(pci_bus,
> > -                         xen_enabled() ? xen_pci_slot_get_pirq
> > -                                       : pc_pci_slot_get_pirq);
> > -        pcms->bus = pci_bus;
> > -
> >          pci_dev = pci_create_simple_multifunction(pci_bus, -1, true,
> >                                                    TYPE_PIIX3_DEVICE);
> >  
> > @@ -290,7 +292,6 @@ static void pc_init1(MachineState *machine,
> >          rtc_state = ISA_DEVICE(object_resolve_path_component(OBJECT(pci_dev),
> >                                                               "rtc"));
> >      } else {
> > -        pci_bus = NULL;
> >          isa_bus = isa_bus_new(NULL, system_memory, system_io,
> >                                &error_abort);
> >    
>