Re: [PATCH v3 06/29] hw/pci-host/gpex-acpi: Split host bridge OSC and DSM generation

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 16 Jun 2025 11:46:35 +0200
Eric Auger <eric.auger@redhat.com> wrote:

> acpi_dsdt_add_pci_osc() name is confusing as it gives the impression
> it appends the _OSC method but in fact it also appends the _DSM method
> for the host bridge. Let's split the function into two separate ones
> and let them return the method Aml pointer instead. This matches the
> way it is done on x86 (build_q35_osc_method). In a subsequent patch
> we will replace the gpex method by the q35 implementation that will
> become shared between ARM and x86.
> 
> acpi_dsdt_add_host_bridge_methods is a new top helper that generates
> both the _OSC and _DSM methods.

I'd get rid of wrapper, but it's not something that worth to fight over,
so

Reviewed-by: Igor Mammedov <imammedo@redhat.com>

> 
> We take the opportunity to move SUPP and CTRL in the _osc method
> that use them.
> 
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> 
> ---
> 
> v2 -> v3:
> - moved
>     aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
>     aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
>   into the _osc function. (Jonathan)
>   hence discarded Gustavo's and Igor's R-bs
> ---
>  hw/pci-host/gpex-acpi.c | 32 +++++++++++++++++++++-----------
>  1 file changed, 21 insertions(+), 11 deletions(-)
> 
> diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
> index f34b7cf25e..80fc2bf032 100644
> --- a/hw/pci-host/gpex-acpi.c
> +++ b/hw/pci-host/gpex-acpi.c
> @@ -50,14 +50,12 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq,
>      }
>  }
>  
> -static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
> +static Aml *build_host_bridge_osc(bool enable_native_pcie_hotplug)
>  {
> -    Aml *method, *UUID, *ifctx, *ifctx1, *elsectx, *buf;
> -
> -    /* Declare an _OSC (OS Control Handoff) method */
> -    aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> -    aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
> +    Aml *method, *UUID, *ifctx, *ifctx1, *elsectx;
>      method = aml_method("_OSC", 4, AML_NOTSERIALIZED);
> +    aml_append(method, aml_name_decl("SUPP", aml_int(0)));
> +    aml_append(method, aml_name_decl("CTRL", aml_int(0)));
>      aml_append(method,
>          aml_create_dword_field(aml_arg(3), aml_int(0), "CDW1"));
>  
> @@ -103,9 +101,13 @@ static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
>                                 aml_name("CDW1")));
>      aml_append(elsectx, aml_return(aml_arg(3)));
>      aml_append(method, elsectx);
> -    aml_append(dev, method);
> +    return method;
> +}
>  
> -    method = aml_method("_DSM", 4, AML_NOTSERIALIZED);
> +static Aml *build_host_bridge_dsm(void)
> +{
> +    Aml *method = aml_method("_DSM", 4, AML_NOTSERIALIZED);
> +    Aml *UUID, *ifctx, *ifctx1, *buf;
>  
>      /* PCI Firmware Specification 3.0
>       * 4.6.1. _DSM for PCI Express Slot Information
> @@ -124,7 +126,15 @@ static void acpi_dsdt_add_pci_osc(Aml *dev, bool enable_native_pcie_hotplug)
>      byte_list[0] = 0;
>      buf = aml_buffer(1, byte_list);
>      aml_append(method, aml_return(buf));
> -    aml_append(dev, method);
> +    return method;
> +}
> +
> +static void acpi_dsdt_add_host_bridge_methods(Aml *dev,
> +                                              bool enable_native_pcie_hotplug)
> +{
> +    /* Declare an _OSC (OS Control Handoff) method */
> +    aml_append(dev, build_host_bridge_osc(enable_native_pcie_hotplug));
> +    aml_append(dev, build_host_bridge_dsm());
>  }
>  
>  void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
> @@ -193,7 +203,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>              if (is_cxl) {
>                  build_cxl_osc_method(dev);
>              } else {
> -                acpi_dsdt_add_pci_osc(dev, true);
> +                acpi_dsdt_add_host_bridge_methods(dev, true);
>              }
>  
>              aml_append(scope, dev);
> @@ -268,7 +278,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
>      }
>      aml_append(dev, aml_name_decl("_CRS", rbuf));
>  
> -    acpi_dsdt_add_pci_osc(dev, true);
> +    acpi_dsdt_add_host_bridge_methods(dev, true);
>  
>      Aml *dev_res0 = aml_device("%s", "RES0");
>      aml_append(dev_res0, aml_name_decl("_HID", aml_string("PNP0C02")));