Re: [PATCH v4 05/13] hw/pci: Add a busnr property to pci_props and use for acpi/gi

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Thu, 11 Jul 2024 14:23:16 +0200
Igor Mammedov <imammedo@redhat.com> wrote:

> On Thu, 11 Jul 2024 13:53:31 +0200
> Igor Mammedov <imammedo@redhat.com> wrote:
> 
> > On Tue, 2 Jul 2024 14:14:10 +0100
> > Jonathan Cameron <Jonathan.Cameron@huawei.com> wrote:
> >   
> > > Using a property allows us to hide the internal details of the PCI device
> > > from the code to build a SRAT Generic Initiator Affinity Structure with
> > > PCI Device Handle.
> > > 
> > > Suggested-by: Igor Mammedov <imammedo@redhat.com>
> > > Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
> > > 
> > > ---
> > > V4: Avoid confusion with device creation parameter bus but renaming to
> > >     busnr
> > > ---
> > >  hw/acpi/acpi_generic_initiator.c | 11 ++++++-----
> > >  hw/pci/pci.c                     | 14 ++++++++++++++
> > >  2 files changed, 20 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/hw/acpi/acpi_generic_initiator.c b/hw/acpi/acpi_generic_initiator.c
> > > index 73bafaaaea..f2711c91ef 100644
> > > --- a/hw/acpi/acpi_generic_initiator.c
> > > +++ b/hw/acpi/acpi_generic_initiator.c
> > > @@ -9,6 +9,7 @@
> > >  #include "hw/boards.h"
> > >  #include "hw/pci/pci_device.h"
> > >  #include "qemu/error-report.h"
> > > +#include "qapi/error.h"
> > >  
> > >  typedef struct AcpiGenericInitiatorClass {
> > >      ObjectClass parent_class;
> > > @@ -79,7 +80,7 @@ static int build_acpi_generic_initiator(Object *obj, void *opaque)
> > >      MachineState *ms = MACHINE(qdev_get_machine());
> > >      AcpiGenericInitiator *gi;
> > >      GArray *table_data = opaque;
> > > -    PCIDevice *pci_dev;
> > > +    uint8_t bus, devfn;
> > >      Object *o;
> > >  
> > >      if (!object_dynamic_cast(obj, TYPE_ACPI_GENERIC_INITIATOR)) {
> > > @@ -100,10 +101,10 @@ static int build_acpi_generic_initiator(Object *obj, void *opaque)
> > >          exit(1);
> > >      }
> > >  
> > > -    pci_dev = PCI_DEVICE(o);
> > > -    build_srat_pci_generic_initiator(table_data, gi->node, 0,
> > > -                                     pci_bus_num(pci_get_bus(pci_dev)),
> > > -                                     pci_dev->devfn);
> > > +    bus = object_property_get_uint(o, "busnr", &error_fatal);
> > > +    devfn = object_property_get_uint(o, "addr", &error_fatal);    
> > 
> > devfn in PCI code is 32bit, while here it's declared as unit8_t,
> > which seems wrong.
> > It likely would work in case of PCIe root ports/switches where slot is 0,
> > but should quickly break elsewhere as soon as slot is more than 0.
> > 
> > If it's intentional, there should be fat comment here about why it this way
> > and an assert to catch silent cropping of the value.   
> 
> Ignore that, obviously the rest of the QEMU does not care about this downcast.
It's indeed odd that the storage is 32 bits.
> 
> Maybe add assert anyways to catch too big devfn returned,
> which unlikely to happen ever.

Will do. 
assert(devfn >= 0 && devfn < PCI_DEVFN_MAX);
with devfn locally as an int32_t and object_property_get_int()
to match with the type.

> 
> anyways:
> 
> Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> 
> >   
> > > +
> > > +    build_srat_pci_generic_initiator(table_data, gi->node, 0, bus, devfn);
> > >  
> > >      return 0;
> > >  }
> > > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > > index 50b86d5790..29d4852c21 100644
> > > --- a/hw/pci/pci.c
> > > +++ b/hw/pci/pci.c
> > > @@ -67,6 +67,19 @@ static char *pcibus_get_fw_dev_path(DeviceState *dev);
> > >  static void pcibus_reset_hold(Object *obj, ResetType type);
> > >  static bool pcie_has_upstream_port(PCIDevice *dev);
> > >  
> > > +static void prop_pci_busnr_get(Object *obj, Visitor *v, const char *name,
> > > +                             void *opaque, Error **errp)
> > > +{
> > > +    uint8_t busnr = pci_dev_bus_num(PCI_DEVICE(obj));
> > > +
> > > +    visit_type_uint8(v, name, &busnr, errp);
> > > +}
> > > +
> > > +static const PropertyInfo prop_pci_busnr = {
> > > +    .name = "busnr",
> > > +    .get = prop_pci_busnr_get,
> > > +};
> > > +
> > >  static Property pci_props[] = {
> > >      DEFINE_PROP_PCI_DEVFN("addr", PCIDevice, devfn, -1),
> > >      DEFINE_PROP_STRING("romfile", PCIDevice, romfile),
> > > @@ -85,6 +98,7 @@ static Property pci_props[] = {
> > >                      QEMU_PCIE_ERR_UNC_MASK_BITNR, true),
> > >      DEFINE_PROP_BIT("x-pcie-ari-nextfn-1", PCIDevice, cap_present,
> > >                      QEMU_PCIE_ARI_NEXTFN_1_BITNR, false),
> > > +    { .name = "busnr", .info = &prop_pci_busnr },
> > >      DEFINE_PROP_END_OF_LIST()
> > >  };
> > >      
> >   
> 
>