Re: [RFC PATCH v3 3/7] hw/pci/pcie: Do not initialize slot capability if acpihp is used

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

On Thu, Sep 24, 2020 at 10:23:13AM +0200, Julia Suvorova wrote:
> On Thu, Sep 24, 2020 at 9:36 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> >
> > On Thu, Sep 24, 2020 at 09:00:09AM +0200, Julia Suvorova wrote:
> > > Instead of changing the hot-plug type in _OSC register, do not
> > > initialize the slot capability or set the 'Slot Implemented' flag.
> > > This way guest will choose ACPI hot-plug if it is preferred and leave
> > > the option to use SHPC with pcie-pci-bridge.
> > >
> > > Signed-off-by: Julia Suvorova <jusual@redhat.com>
> > > ---
> > >  hw/i386/acpi-build.h |  2 ++
> > >  hw/i386/acpi-build.c |  2 +-
> > >  hw/pci/pcie.c        | 16 ++++++++++++++++
> > >  3 files changed, 19 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/hw/i386/acpi-build.h b/hw/i386/acpi-build.h
> > > index 487ec7710f..4c5bfb3d0b 100644
> > > --- a/hw/i386/acpi-build.h
> > > +++ b/hw/i386/acpi-build.h
> > > @@ -11,4 +11,6 @@ extern const struct AcpiGenericAddress x86_nvdimm_acpi_dsmio;
> > >
> > >  void acpi_setup(void);
> > >
> > > +Object *object_resolve_type_unambiguous(const char *typename);
> > > +
> > >  #endif
> > > diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> > > index cf503b16af..b7811a8912 100644
> > > --- a/hw/i386/acpi-build.c
> > > +++ b/hw/i386/acpi-build.c
> > > @@ -174,7 +174,7 @@ static void init_common_fadt_data(MachineState *ms, Object *o,
> > >      *data = fadt;
> > >  }
> > >
> > > -static Object *object_resolve_type_unambiguous(const char *typename)
> > > +Object *object_resolve_type_unambiguous(const char *typename)
> > >  {
> > >      bool ambig;
> > >      Object *o = object_resolve_path_type("", typename, &ambig);
> > > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > > index 5b48bae0f6..c1a082e8b9 100644
> > > --- a/hw/pci/pcie.c
> > > +++ b/hw/pci/pcie.c
> > > @@ -27,6 +27,8 @@
> > >  #include "hw/pci/pci_bus.h"
> > >  #include "hw/pci/pcie_regs.h"
> > >  #include "hw/pci/pcie_port.h"
> > > +#include "hw/i386/ich9.h"
> > > +#include "hw/i386/acpi-build.h"
> > >  #include "qemu/range.h"
> > >
> > >  //#define DEBUG_PCIE
> >
> >
> > Not really happy with pcie.c getting an i386 dependency.
> >
> >
> >
> > > @@ -515,12 +517,26 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
> > >      pcie_cap_slot_push_attention_button(hotplug_pdev);
> > >  }
> > >
> > > +static bool acpi_pcihp_enabled(void)
> > > +{
> > > +    Object *lpc = object_resolve_type_unambiguous(TYPE_ICH9_LPC_DEVICE);
> > > +
> > > +    return lpc &&
> > > +           object_property_get_bool(lpc, "acpi-pci-hotplug-with-bridge-support",
> > > +                                    NULL);
> > > +
> > > +}
> > > +
> >
> > Why not just check the property unconditionally?
> 
> Ok.
> 
> > >  /* pci express slot for pci express root/downstream port
> > >     PCI express capability slot registers */
> > >  void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
> > >  {
> > >      uint32_t pos = dev->exp.exp_cap;
> > >
> > > +    if (acpi_pcihp_enabled()) {
> > > +        return;
> > > +    }
> > > +
> >
> > I think I would rather not teach pcie about acpi. How about we
> > change the polarity, name the property
> > "pci-native-hotplug" or whatever makes sense.
> 
> I'd prefer not to change the property name since the common code in
> hw/i386/acpi-build.c depends on it, but I can add a new one if it
> makes any sense.

And maybe prefix with "x-" so we don't commit to it as an
external API.


> > >      pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_FLAGS,
> > >                                 PCI_EXP_FLAGS_SLOT);
> > >
> > > --
> > > 2.25.4
> >