Re: [Qemu-devel] [v4][PATCH 3/5] I440FX_PCI_DEVICE: add pci_type to index

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

On Mon, Aug 11, 2014 at 10:50:48AM +0800, Chen, Tiejun wrote:
> On 2014/8/11 4:27, Michael S. Tsirkin wrote:
> >On Thu, Aug 07, 2014 at 09:40:49AM +0800, Chen, Tiejun wrote:
> >>
> >>
> >>On 2014/8/7 5:07, Michael S. Tsirkin wrote:
> >>>On Wed, Aug 06, 2014 at 06:17:02PM +0800, Chen, Tiejun wrote:
> >>>>On 2014/8/6 17:45, Michael S. Tsirkin wrote:
> >>>>>On Wed, Aug 06, 2014 at 02:50:33PM +0800, Tiejun Chen wrote:
> >>>>>>We need to use this index to reuse this macro later
> >>>>>>
> >>>>>>Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> >>>>>
> >>>>>Which index?
> >>>>>Most users don't need to change.
> >>>>>Just open-code OBJECT_CHECK where necessary, or add
> >>>>>a new wrapper.
> >>>>
> >>>>Okay so what about this?
> >>>>
> >>>>     hw:pci-host:piix: define I440FX_PCI_DEVICE_FROM_TYPE
> >>>>
> >>>>     We need to introduce I440FX_PCI_DEVICE_FROM_TYPE to get
> >>>>     object with type, then we can reuse i440fx_init() simply.
> >>>>
> >>>>     Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> >>>>
> >>>>diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> >>>>index 0cd82b8..8c74653 100644
> >>>>--- a/hw/pci-host/piix.c
> >>>>+++ b/hw/pci-host/piix.c
> >>>>@@ -93,6 +93,9 @@ typedef struct PIIX3State {
> >>>>  #define I440FX_PCI_DEVICE(obj) \
> >>>>      OBJECT_CHECK(PCII440FXState, (obj), TYPE_I440FX_PCI_DEVICE)
> >>>>
> >>>>+#define I440FX_PCI_DEVICE_FROM_TYPE(obj, type) \
> >>>>+    OBJECT_CHECK(PCII440FXState, (obj), type)
> >>>
> >>>This is just wrong. If you are casting to PCII440FXState,
> >>
> >>Why? We will have two different QOM typenames of PCII440FXStates.
> >>
> >>>there is no reason not to use TYPE_I440FX_PCI_DEVICE.
> >>
> >>As you know we already have this original,
> >>
> >>static const TypeInfo i440fx_info = {
> >>     .name          = TYPE_I440FX_PCI_DEVICE,
> >>     .parent        = TYPE_PCI_DEVICE,
> >>     .instance_size = sizeof(PCII440FXState),
> >>     .class_init    = i440fx_class_init,
> >>};
> >>
> >>and in patch #4, we will register that new host bridge to IGD passthrough:
> >>
> >>static const TypeInfo xen_igd_passthrough_i440fx_info = {
> >>     .name          = TYPE_XEN_IGD_PASSTHROUGH_I440FX_PCI_DEVICE,
> >>     .parent        = TYPE_PCI_DEVICE,
> >>     .instance_size = sizeof(PCII440FXState),
> >>     .class_init    = xen_igd_passthrough_i440fx_class_init,
> >>};
> >
> >My idea is to inherit TYPE_I440FX_PCI_DEVICE instead.
> 
> So here, this mean xen_igd_passthrough_i440fx_info's parent should be
> TYPE_I440FX_PCI_DEVICE, right?
> 
> >Then you can reuse regular piix code which casts to
> >TYPE_I440FX_PCI_DEVICE because
> >TYPE_XEN_IGD_PASSTHROUGH_I440FX_PCI_DEVICE would
> >be a subclass of TYPE_I440FX_PCI_DEVICE.
> >
> 
> So since then, we can reuse i440fx_initfn.
> 
> As a summary, what we should do is like the following,
> 
> xen:hw:pci-host:piix: create host bridge to passthrough
> 
> Implement a pci host bridge specific to passthrough. Actually
> this just inherits the standard one.
> 
> This is based on http://patchwork.ozlabs.org/patch/363810/.
> 
> Signed-off-by: Tiejun Chen <tiejun.chen@intel.com>
> ---
>  hw/pci-host/piix.c   | 28 ++++++++++++++++++++++++++++
>  include/hw/i386/pc.h |  2 ++
>  2 files changed, 30 insertions(+)
> 
> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> index 0cd82b8..2ccd9ee 100644
> --- a/hw/pci-host/piix.c
> +++ b/hw/pci-host/piix.c
> @@ -703,6 +703,33 @@ static const TypeInfo i440fx_info = {
>      .class_init    = i440fx_class_init,
>  };
> 
> +static void xen_igd_passthrough_i440fx_class_init(ObjectClass *klass, void
> *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
> +
> +    k->init = i440fx_initfn;
> +    k->vendor_id = PCI_VENDOR_ID_INTEL;
> +    k->device_id = PCI_DEVICE_ID_INTEL_82441;
> +    k->revision = 0x02;
> +    k->class_id = PCI_CLASS_BRIDGE_HOST;
> +    dc->desc = "IGD PT XEN Host bridge";
> +    dc->vmsd = &vmstate_i440fx;
> +    /*
> +     * PCI-facing part of the host bridge, not usable without the
> +     * host-facing part, which can't be device_add'ed, yet.
> +     */
> +    dc->cannot_instantiate_with_device_add_yet = true;
> +    dc->hotpluggable   = false;
> +}
> +

A bunch of code still duplicated here. Only override what you have to.


> +static const TypeInfo xen_igd_passthrough_i440fx_info = {
> +    .name          = TYPE_XEN_IGD_PASSTHROUGH_I440FX_PCI_DEVICE,
> +    .parent        = TYPE_I440FX_PCI_DEVICE,
> +    .instance_size = sizeof(PCII440FXState),
> +    .class_init    = xen_igd_passthrough_i440fx_class_init,
> +};
> +
>  static const char *i440fx_pcihost_root_bus_path(PCIHostState *host_bridge,
>                                                  PCIBus *rootbus)
>  {
> @@ -744,6 +771,7 @@ static const TypeInfo i440fx_pcihost_info = {
>  static void i440fx_register_types(void)
>  {
>      type_register_static(&i440fx_info);
> +    type_register_static(&xen_igd_passthrough_i440fx_info);
>      type_register_static(&piix3_info);
>      type_register_static(&piix3_xen_info);
>      type_register_static(&i440fx_pcihost_info);
> diff --git a/include/hw/i386/pc.h b/include/hw/i386/pc.h
> index 11fb72f..de34aa6 100644
> --- a/include/hw/i386/pc.h
> +++ b/include/hw/i386/pc.h
> @@ -238,6 +238,8 @@ typedef struct PCII440FXState PCII440FXState;
>  #define TYPE_I440FX_PCI_HOST_BRIDGE "i440FX-pcihost"
>  #define TYPE_I440FX_PCI_DEVICE "i440FX"
> 
> +#define TYPE_XEN_IGD_PASSTHROUGH_I440FX_PCI_DEVICE
> "xen-igd-passthrough-i440FX"
> +
>  PCIBus *i440fx_init(const char *host_type, const char *pci_type,
>                      PCII440FXState **pi440fx_state, int *piix_devfn,
>                      ISABus **isa_bus, qemu_irq *pic,
> -- 
> 1.9.1
> 
> Thanks
> Tiejun