Re: [PATCH v4 1/9] hw/pci-host/i440fx: Inline sysbus_add_io()

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 13/2/23 17:19, Bernhard Beschow wrote:
> sysbus_add_io() just wraps memory_region_add_subregion() while also
> obscuring where the memory is attached. So use
> memory_region_add_subregion() directly and attach it to the existing
> memory region s->bus->address_space_io which is set as an alias to
> get_system_io() by the pc machine.
> 
> Signed-off-by: Bernhard Beschow <shentey@gmail.com>
> Reviewed-by: Thomas Huth <thuth@redhat.com>
> ---
>   hw/pci-host/i440fx.c | 5 +++--
>   1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci-host/i440fx.c b/hw/pci-host/i440fx.c
> index 262f82c303..9c6882d3fc 100644
> --- a/hw/pci-host/i440fx.c
> +++ b/hw/pci-host/i440fx.c
> @@ -27,6 +27,7 @@
>   #include "qemu/range.h"
>   #include "hw/i386/pc.h"
>   #include "hw/pci/pci.h"
> +#include "hw/pci/pci_bus.h"
>   #include "hw/pci/pci_host.h"
>   #include "hw/pci-host/i440fx.h"
>   #include "hw/qdev-properties.h"
> @@ -217,10 +218,10 @@ static void i440fx_pcihost_realize(DeviceState *dev, Error **errp)
>       PCIHostState *s = PCI_HOST_BRIDGE(dev);
>       SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
>   
> -    sysbus_add_io(sbd, 0xcf8, &s->conf_mem);
> +    memory_region_add_subregion(s->bus->address_space_io, 0xcf8, &s->conf_mem);

To avoid accessing internal fields we should stick to the PCI API:

     memory_region_add_subregion(pci_address_space_io(PCI_DEVICE(dev)),
                                 0xcf8, &s->conf_mem);

>       sysbus_init_ioports(sbd, 0xcf8, 4);
>   
> -    sysbus_add_io(sbd, 0xcfc, &s->data_mem);
> +    memory_region_add_subregion(s->bus->address_space_io, 0xcfc, &s->data_mem);
>       sysbus_init_ioports(sbd, 0xcfc, 4);

Now all classes implementing PCI_HOST_BRIDGE register conf/data in I/O
space, so this could be a pattern justifying reworking a bit the
PCIHostBridgeClass or adding an helper in "hw/pci/pci_host.h" to do
that generically.