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

[Ani Sinha <ani@anisinha.ca>]

On Thu, 24 Sep 2020, Igor Mammedov wrote:

> 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?

+1 to Igor's suggestion.


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