Re: [PATCH 1/5] hw/pci/pcie_port: Rename 'native-hotplug' to 'native-hpc-bit'

[Michael S. Tsirkin]

On Wed, Nov 10, 2021 at 02:30:27PM +0100, Igor Mammedov wrote:
> On Wed, 10 Nov 2021 09:08:34 +0000
> Daniel P. Berrangé <berrange@redhat.com> wrote:
> 
> > On Wed, Nov 10, 2021 at 01:04:54AM -0500, Michael S. Tsirkin wrote:
> > > On Wed, Nov 10, 2021 at 06:30:10AM +0100, Julia Suvorova wrote:  
> > > > Rename the option to better represent its function - toggle Hot-Plug
> > > > Capable bit in the PCIe Slot Capability.
> > > > 
> > > > Signed-off-by: Julia Suvorova <jusual@redhat.com>
> > > > ---
> > > >  include/hw/pci/pcie_port.h         | 2 +-
> > > >  hw/i386/pc_q35.c                   | 2 +-
> > > >  hw/pci-bridge/gen_pcie_root_port.c | 6 +++++-
> > > >  hw/pci/pcie.c                      | 2 +-
> > > >  hw/pci/pcie_port.c                 | 2 +-
> > > >  5 files changed, 9 insertions(+), 5 deletions(-)
> > > > 
> > > > diff --git a/include/hw/pci/pcie_port.h b/include/hw/pci/pcie_port.h
> > > > index e25b289ce8..0da6d66c95 100644
> > > > --- a/include/hw/pci/pcie_port.h
> > > > +++ b/include/hw/pci/pcie_port.h
> > > > @@ -60,7 +60,7 @@ struct PCIESlot {
> > > >      /* Indicates whether any type of hot-plug is allowed on the slot */
> > > >      bool        hotplug;
> > > >  
> > > > -    bool        native_hotplug;
> > > > +    bool        native_hpc_bit;
> > > >  
> > > >      QLIST_ENTRY(PCIESlot) next;
> > > >  };
> > > > diff --git a/hw/i386/pc_q35.c b/hw/i386/pc_q35.c  
> > > 
> > > 
> > > This is ok.
> > > 
> > >   
> > > > index 797e09500b..ded61f8ef7 100644
> > > > --- a/hw/i386/pc_q35.c
> > > > +++ b/hw/i386/pc_q35.c
> > > > @@ -243,7 +243,7 @@ static void pc_q35_init(MachineState *machine)
> > > >                                            NULL);
> > > >  
> > > >      if (acpi_pcihp) {
> > > > -        object_register_sugar_prop(TYPE_PCIE_SLOT, "native-hotplug",
> > > > +        object_register_sugar_prop(TYPE_PCIE_SLOT, "native-hpc-bit",
> > > >                                     "false", true);
> > > >      }
> > > >  
> > > 
> > > 
> > > This part is problematic since we made the feature user-settable in 6.1.
> > > We can have two features if we really want to ...
> > > I don't think we have a way to mark properties deprecated, do we? 
> 
> describe them in deprecated.rst
>  
> > 
> > IMHO just leave the feature with its current name. It won't be the
> > first thing without a "perfect" name and the name doesn't have a
> > negative impact on mgmt apps. Changing the name will cause more
> > pain than it solves.
> 
> looking at the code, it was introduced in 6.1 for internal needs mostly
> 
>  3f3cbbb23 hw/pci/pcie: Do not set HPC flag if acpihp is used
> 
> to hide slot from guest's native-hotplug module.
> Even if user tried explicitly to set native-hoplug=on on a slot
> with ACPI hotplug enabled, native hotplug will not work properly
> as slot's hotplug is still handled by acpi_pcihp_device_plug_cb().
> 
> Given above and that it shouldn't been used by users,
> I'd rather rename it to x-native-hotplug now than go through deprecation
> process and expose it for 2 more releases.
> 

Well what works is disabling native hotplug. Has same effect as
disabling hotplug really. Yes, I see little point
in keeping it. Technically an ABI breakage but hey.
And I would also try to backport a patch renaming it to stable
(if another stable release happens). So users don't start
using this.

> > >     
> > > > diff --git a/hw/pci-bridge/gen_pcie_root_port.c 
> > > > b/hw/pci-bridge/gen_pcie_root_port.c
> > > > index 20099a8ae3..ed079d72b3 100644
> > > > --- a/hw/pci-bridge/gen_pcie_root_port.c
> > > > +++ b/hw/pci-bridge/gen_pcie_root_port.c
> > > > @@ -87,7 +87,11 @@ static void gen_rp_realize(DeviceState *dev, Error 
> > > > **errp)
> > > >          return;
> > > >      }
> > > >  
> > > > -    if (grp->res_reserve.io == -1 && s->hotplug && !s->native_hotplug) 
> > > > {
> > > > +    /*
> > > > +     * Make sure that IO is assigned in case the slot is hot-pluggable
> > > > +     * but it is not visible through the PCIe Slot Capabilities
> > > > +     */
> > > > +    if (grp->res_reserve.io == -1 && s->hotplug && !s->native_hpc_bit) 
> > > > {
> > > >          grp->res_reserve.io = GEN_PCIE_ROOT_DEFAULT_IO_RANGE;
> > > >      }
> > > >      int rc = pci_bridge_qemu_reserve_cap_init(d, 0,
> > > > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > > > index 914a9bf3d1..ebe002831e 100644
> > > > --- a/hw/pci/pcie.c
> > > > +++ b/hw/pci/pcie.c
> > > > @@ -535,7 +535,7 @@ void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
> > > >       * hot-plug is disabled on the slot.
> > > >       */
> > > >      if (s->hotplug &&
> > > > -        (s->native_hotplug || DEVICE(dev)->hotplugged)) {
> > > > +        (s->native_hpc_bit || DEVICE(dev)->hotplugged)) {
> > > >          pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
> > > >                                     PCI_EXP_SLTCAP_HPS |
> > > >                                     PCI_EXP_SLTCAP_HPC);
> > > > diff --git a/hw/pci/pcie_port.c b/hw/pci/pcie_port.c
> > > > index da850e8dde..eae06d10e2 100644
> > > > --- a/hw/pci/pcie_port.c
> > > > +++ b/hw/pci/pcie_port.c
> > > > @@ -148,7 +148,7 @@ static Property pcie_slot_props[] = {
> > > >      DEFINE_PROP_UINT8("chassis", PCIESlot, chassis, 0),
> > > >      DEFINE_PROP_UINT16("slot", PCIESlot, slot, 0),
> > > >      DEFINE_PROP_BOOL("hotplug", PCIESlot, hotplug, true),
> > > > -    DEFINE_PROP_BOOL("native-hotplug", PCIESlot, native_hotplug, true),
> > > > +    DEFINE_PROP_BOOL("native-hpc-bit", PCIESlot, native_hpc_bit, true),
> > > >      DEFINE_PROP_END_OF_LIST()
> > > >  };
> > > >  
> > > > -- 
> > > > 2.31.1  
> > > 
> > >   
> > 
> > Regards,
> > Daniel