Re: [Qemu-devel] [PATCH] spapr: make default PHB optionnal

[Greg Kurz <groug@kaod.org>]

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On Wed, 19 Jul 2017 14:34:42 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Tue, Jul 04, 2017 at 10:47:22AM +0200, Greg Kurz wrote:
> > On Tue, 4 Jul 2017 17:29:01 +1000
> > David Gibson <david@gibson.dropbear.id.au> wrote:
> >   
> > > On Mon, Jul 03, 2017 at 06:48:25PM +0200, Greg Kurz wrote:  
> > > > The sPAPR machine always create a default PHB during initialization, even
> > > > if -nodefaults was passed on the command line. This forces the user to
> > > > rely on -global if she wants to set properties of the default PHB, such
> > > > as numa_node.
> > > > 
> > > > This patch introduces a new machine create-default-phb property to control
> > > > whether the default PHB must be created or not. It defaults to on in order
> > > > to preserve old setups (which is also the motivation to not alter the
> > > > current behavior of -nodefaults).
> > > > 
> > > > If create-default-phb is set to off, the default PHB isn't created, nor
> > > > any other device usually created with it. It is mandatory to provide
> > > > a PHB on the command line to be able to use PCI devices (otherwise QEMU
> > > > won't start). For example, the following creates a PHB with the same
> > > > mappings as the default PHB and also sets the NUMA affinity:
> > > > 
> > > >     -machine type=pseries,create-default-phb=off \
> > > >     -numa node,nodeid=0 -device spapr-pci-host-bridge,index=0,numa_node=0
> > > > 
> > > > Signed-off-by: Greg Kurz <groug@kaod.org>    
> > > 
> > > So, I agree that the distinction between default devices that are
> > > disabled with -nodefaults and default devices that aren't is a big
> > > mess in qemu configuration.  But on the other hand this only addresses
> > > one tiny aspect of that, and in the meantime means we will silently
> > > ignore some other configuration options in some conditions.
> > > 
> > > So, what's the immediate benefit / use case for this?
> > >   
> > 
> > With the current code base, the only way to set properties of the default
> > PHB, is to pass -global spapr-pci-host-bridge.prop=value for each property.
> > The immediate benefit of this patch is to unify the way libvirt passes
> > PHB description to the command line:  
> 
> I thought you could use -set to set things more explicitly.  But I'll
> admit, I can never remember how the syntax of that works.

IIUC, -set is handled by qemu_set_option() which gets called way
earlier than ppc_spapr_init->spapr_create_phb(), ie, it only works
for devices created with -device, not for the default PHB.

> > 
> > ie, do:
> > 
> >     -machine type=pseries,create-default-phb=off \
> >     -device spapr-pci-host-bridge,prop1=a,prop2=b,prop3=c \
> >     -device spapr-pci-host-bridge,prop1=d,prop2=e,prop3=f
> > 
> > instead of:
> > 
> >     -machine type=pseries \
> >     -global spapr-pci-host-bridge.prop1=a \
> >     -global spapr-pci-host-bridge.prop2=b \
> >     -global spapr-pci-host-bridge.prop3=c \
> >     -device spapr-pci-host-bridge,prop1=d,prop2=e,prop3=f
> >   
> > > > ---
> > > >  hw/ppc/spapr.c         |   63 ++++++++++++++++++++++++++++++++++--------------
> > > >  include/hw/ppc/spapr.h |    2 ++
> > > >  2 files changed, 47 insertions(+), 18 deletions(-)
> > > > 
> > > > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
> > > > index ba8f57a5a054..3395bb3774b9 100644
> > > > --- a/hw/ppc/spapr.c
> > > > +++ b/hw/ppc/spapr.c
> > > > @@ -2103,7 +2103,7 @@ static void ppc_spapr_init(MachineState *machine)
> > > >      sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(machine);
> > > >      const char *kernel_filename = machine->kernel_filename;
> > > >      const char *initrd_filename = machine->initrd_filename;
> > > > -    PCIHostState *phb;
> > > > +    PCIHostState *phb = NULL;
> > > >      int i;
> > > >      MemoryRegion *sysmem = get_system_memory();
> > > >      MemoryRegion *ram = g_new(MemoryRegion, 1);
> > > > @@ -2294,7 +2294,9 @@ static void ppc_spapr_init(MachineState *machine)
> > > >      /* Set up PCI */
> > > >      spapr_pci_rtas_init();
> > > >  
> > > > -    phb = spapr_create_phb(spapr, 0);
> > > > +    if (spapr->create_default_phb) {
> > > > +        phb = spapr_create_phb(spapr, 0);
> > > > +    }
> > > >  
> > > >      for (i = 0; i < nb_nics; i++) {
> > > >          NICInfo *nd = &nd_table[i];
> > > > @@ -2305,7 +2307,7 @@ static void ppc_spapr_init(MachineState *machine)
> > > >  
> > > >          if (strcmp(nd->model, "ibmveth") == 0) {
> > > >              spapr_vlan_create(spapr->vio_bus, nd);
> > > > -        } else {
> > > > +        } else if (phb) {
> > > >              pci_nic_init_nofail(&nd_table[i], phb->bus, nd->model, NULL);
> > > >          }
> > > >      }
> > > > @@ -2314,24 +2316,26 @@ static void ppc_spapr_init(MachineState *machine)
> > > >          spapr_vscsi_create(spapr->vio_bus);
> > > >      }
> > > >  
> > > > -    /* Graphics */
> > > > -    if (spapr_vga_init(phb->bus, &error_fatal)) {
> > > > -        spapr->has_graphics = true;
> > > > -        machine->usb |= defaults_enabled() && !machine->usb_disabled;
> > > > -    }
> > > > -
> > > > -    if (machine->usb) {
> > > > -        if (smc->use_ohci_by_default) {
> > > > -            pci_create_simple(phb->bus, -1, "pci-ohci");
> > > > -        } else {
> > > > -            pci_create_simple(phb->bus, -1, "nec-usb-xhci");
> > > > +    if (phb) {
> > > > +        /* Graphics */
> > > > +        if (spapr_vga_init(phb->bus, &error_fatal)) {
> > > > +            spapr->has_graphics = true;
> > > > +            machine->usb |= defaults_enabled() && !machine->usb_disabled;
> > > >          }
> > > >  
> > > > -        if (spapr->has_graphics) {
> > > > -            USBBus *usb_bus = usb_bus_find(-1);
> > > > +        if (machine->usb) {
> > > > +            if (smc->use_ohci_by_default) {
> > > > +                pci_create_simple(phb->bus, -1, "pci-ohci");
> > > > +            } else {
> > > > +                pci_create_simple(phb->bus, -1, "nec-usb-xhci");
> > > > +            }
> > > > +
> > > > +            if (spapr->has_graphics) {
> > > > +                USBBus *usb_bus = usb_bus_find(-1);
> > > >  
> > > > -            usb_create_simple(usb_bus, "usb-kbd");
> > > > -            usb_create_simple(usb_bus, "usb-mouse");
> > > > +                usb_create_simple(usb_bus, "usb-kbd");
> > > > +                usb_create_simple(usb_bus, "usb-mouse");
> > > > +            }
> > > >          }
> > > >      }
> > > >  
> > > > @@ -2544,12 +2548,27 @@ static void spapr_set_modern_hotplug_events(Object *obj, bool value,
> > > >      spapr->use_hotplug_event_source = value;
> > > >  }
> > > >  
> > > > +static bool spapr_get_create_default_phb(Object *obj, Error **errp)
> > > > +{
> > > > +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> > > > +
> > > > +    return spapr->create_default_phb;
> > > > +}
> > > > +
> > > > +static void spapr_set_create_default_phb(Object *obj, bool value, Error **errp)
> > > > +{
> > > > +    sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> > > > +
> > > > +    spapr->create_default_phb = value;
> > > > +}
> > > > +
> > > >  static void spapr_machine_initfn(Object *obj)
> > > >  {
> > > >      sPAPRMachineState *spapr = SPAPR_MACHINE(obj);
> > > >  
> > > >      spapr->htab_fd = -1;
> > > >      spapr->use_hotplug_event_source = true;
> > > > +    spapr->create_default_phb = true;
> > > >      object_property_add_str(obj, "kvm-type",
> > > >                              spapr_get_kvm_type, spapr_set_kvm_type, NULL);
> > > >      object_property_set_description(obj, "kvm-type",
> > > > @@ -2568,6 +2587,14 @@ static void spapr_machine_initfn(Object *obj)
> > > >      ppc_compat_add_property(obj, "max-cpu-compat", &spapr->max_compat_pvr,
> > > >                              "Maximum permitted CPU compatibility mode",
> > > >                              &error_fatal);
> > > > +
> > > > +    object_property_add_bool(obj, "create-default-phb",
> > > > +                            spapr_get_create_default_phb,
> > > > +                            spapr_set_create_default_phb,
> > > > +                            NULL);
> > > > +    object_property_set_description(obj, "create-default-phb",
> > > > +                                    "Create a default PCI Host Bridge",
> > > > +                                    NULL);
> > > >  }
> > > >  
> > > >  static void spapr_machine_finalizefn(Object *obj)
> > > > diff --git a/include/hw/ppc/spapr.h b/include/hw/ppc/spapr.h
> > > > index a184ffab0ebc..6ee914764807 100644
> > > > --- a/include/hw/ppc/spapr.h
> > > > +++ b/include/hw/ppc/spapr.h
> > > > @@ -93,6 +93,8 @@ struct sPAPRMachineState {
> > > >      bool use_hotplug_event_source;
> > > >      sPAPREventSource *event_sources;
> > > >  
> > > > +    bool create_default_phb;
> > > > +
> > > >      /* ibm,client-architecture-support option negotiation */
> > > >      bool cas_reboot;
> > > >      bool cas_legacy_guest_workaround;
> > > >     
> > >   
> >   
> 
> 
> 


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