Re: [PATCH v5 2/5] i386/pc: create pci-host qdev prior to pc_memory_init()

[Mark Cave-Ayland]

On 16/06/2022 14:21, Reviewed-by: Igor Mammedov wrote:

> On Fri, 20 May 2022 11:45:29 +0100
> Joao Martins <joao.m.martins@oracle.com> wrote:
>
> > At the start of pc_memory_init() we usually pass a range of
> > 0..UINT64_MAX as pci_memory, when really its 2G (i440fx) or
> > 32G (q35). To get the real user value, we need to get pci-host
> > passed property for default pci_hole64_size. Thus to get that,
> > create the qdev prior to memory init to better make estimations
> > on max used/phys addr.
> >
> > This is in preparation to determine that host-phys-bits are
> > enough and also for pci-hole64-size to be considered to relocate
> > ram-above-4g to be at 1T (on AMD platforms).
>
> with comments below fixed
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
>   
> > Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
> > ---
> >   hw/i386/pc_piix.c            | 5 ++++-
> >   hw/i386/pc_q35.c             | 6 +++---
> >   hw/pci-host/i440fx.c         | 3 +--
> >   include/hw/pci-host/i440fx.h | 2 +-
> >   4 files changed, 9 insertions(+), 7 deletions(-)
> >
> > diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c
> > index 578e537b3525..12d4a279c793 100644
> > --- a/hw/i386/pc_piix.c
> > +++ b/hw/i386/pc_piix.c
> > @@ -91,6 +91,7 @@ static void pc_init1(MachineState *machine,
> >       MemoryRegion *pci_memory;
> >       MemoryRegion *rom_memory;
> >       ram_addr_t lowmem;
> > +    DeviceState *i440fx_dev;
> >   
> >       /*
> >        * Calculate ram split, for memory below and above 4G.  It's a bit
> > @@ -164,9 +165,11 @@ static void pc_init1(MachineState *machine,
> >           pci_memory = g_new(MemoryRegion, 1);
> >           memory_region_init(pci_memory, NULL, "pci", UINT64_MAX);
> >           rom_memory = pci_memory;
> > +        i440fx_dev = qdev_new(host_type);
> >       } else {
> >           pci_memory = NULL;
> >           rom_memory = system_memory;
> > +        i440fx_dev = NULL;
> >       }
> >   
> >       pc_guest_info_init(pcms);
> > @@ -199,7 +202,7 @@ static void pc_init1(MachineState *machine,
> >   
> >           pci_bus = i440fx_init(host_type,
> >                                 pci_type,
> > -                              &i440fx_state,
> > +                              i440fx_dev, &i440fx_state,
> confusing names, suggest to rename i440fx_state -> pci_i440fx and i440fx_dev -> 
> i440fx_host
> or something like this

It might be worth considering this series on top of Bernhard's patch here: 
https://lists.gnu.org/archive/html/qemu-devel/2022-06/msg02206.html.

> >                                 system_memory, system_io, machine->ram_size,
> >                                 x86ms->below_4g_mem_size,
> >                                 x86ms->above_4g_mem_size,
> > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c
> > index 42eb8b97079a..8d867bdb274a 100644
> > --- a/hw/i386/pc_q35.c
> > +++ b/hw/i386/pc_q35.c
> > @@ -203,12 +203,12 @@ static void pc_q35_init(MachineState *machine)
> >                               pcms->smbios_entry_point_type);
> >       }
> >   
> > -    /* allocate ram and load rom/bios */
> > -    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory);
> > -
> >       /* create pci host bus */
> >       q35_host = Q35_HOST_DEVICE(qdev_new(TYPE_Q35_HOST_DEVICE));
> >   
> > +    /* allocate ram and load rom/bios */
> > +    pc_memory_init(pcms, get_system_memory(), rom_memory, &ram_memory);
> > +
> >       object_property_add_child(qdev_get_machine(), "q35", OBJECT(q35_host));
> >       object_property_set_link(OBJECT(q35_host), MCH_HOST_PROP_RAM_MEM,
> >                                OBJECT(ram_memory), NULL);
> > diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> > index e08716142b6e..5c1bab5c58ed 100644
> > --- a/hw/pci-host/i440fx.c
> > +++ b/hw/pci-host/i440fx.c
> > @@ -238,6 +238,7 @@ static void i440fx_realize(PCIDevice *dev, Error **errp)
> >   }
> >   
> >   PCIBus *i440fx_init(const char *host_type, const char *pci_type,
>
> does it still need 'host_type'?
>
> > +                    DeviceState *dev,
> >                       PCII440FXState **pi440fx_state,
> >                       MemoryRegion *address_space_mem,
> >                       MemoryRegion *address_space_io,
> > @@ -247,7 +248,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
> > *pci_type,
> >                       MemoryRegion *pci_address_space,
> >                       MemoryRegion *ram_memory)
> >   {
> > -    DeviceState *dev;
> >       PCIBus *b;
> >       PCIDevice *d;
> >       PCIHostState *s;
> > @@ -255,7 +255,6 @@ PCIBus *i440fx_init(const char *host_type, const char 
> > *pci_type,
> >       unsigned i;
> >       I440FXState *i440fx;
> >   
> > -    dev = qdev_new(host_type);
> >       s = PCI_HOST_BRIDGE(dev);
> >       b = pci_root_bus_new(dev, NULL, pci_address_space,
> >                            address_space_io, 0, TYPE_PCI_BUS);
> > diff --git a/include/hw/pci-host/i440fx.h b/include/hw/pci-host/i440fx.h
> > index f068aaba8fda..c4710445e30a 100644
> > --- a/include/hw/pci-host/i440fx.h
> > +++ b/include/hw/pci-host/i440fx.h
> > @@ -36,7 +36,7 @@ struct PCII440FXState {
> >   #define TYPE_IGD_PASSTHROUGH_I440FX_PCI_DEVICE "igd-passthrough-i440FX"
> >   
> >   PCIBus *i440fx_init(const char *host_type, const char *pci_type,
> > -                    PCII440FXState **pi440fx_state,
> > +                    DeviceState *dev, PCII440FXState **pi440fx_state,
> >                       MemoryRegion *address_space_mem,
> >                       MemoryRegion *address_space_io,
> >                       ram_addr_t ram_size,


ATB,

Mark.