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

[Julia Suvorova]

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.

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