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

[Igor Mammedov <imammedo@redhat.com>]

On Thu, 24 Sep 2020 09:00:09 +0200
Julia Suvorova <jusual@redhat.com> 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
> @@ -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);
> +
> +}
> +
>  /* 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;
> +    }
> +
>      pci_word_test_and_set_mask(dev->config + pos + PCI_EXP_FLAGS,
>                                 PCI_EXP_FLAGS_SLOT);
>  
why do you drop all slot caps instead of disabling just "if (s->hotplug) {" branch?