Re: [Qemu-devel] [PATCH V2] hw/pxb-pcie: fix PCI Express hotplug support

[Igor Mammedov]

On Thu, 23 Feb 2017 13:59:17 +0200
Marcel Apfelbaum <address@hidden> wrote:

> Add the missing osc method for pxb-pcie devices as APCI spec recommends,
> see 6.2.10.3 OSC Implementation Example for PCI Host Bridge Devices, ACPI 5.0:
> 
>     It is recommended that a machine with multiple host bridge devices
>     should report the same capabilities for all host bridges, and also
>     negotiate control of the features described in the Control Field in
>     the same way for all host bridges.
> 
> Signed-off-by: Marcel Apfelbaum <address@hidden>
> ---
> 
> Note to maintainer:
>  Please update ACPI test files.
> 
> V1 -> V2:
>     Addressed Michael S. Tsirkin's comments:
>       - Added documentation to q35 osc function
>       - Made _osc serialized. I did not add compat property
>         since it seems guest OSs do not care anyway about the OSC
>         being serialized.
>       - Kept the SUPP field even if is not used and also
>         left both SUPP and CTRL out of the _osc because all
>         systems I checked and the ACPI spec keep them that way,
>         maybe is some kind of documentation contract.
> 
> Thanks,
> Marcel
> 
> 
>  hw/i386/acpi-build.c | 41 +++++++++++++++++++++++++++++++++++------
>  1 file changed, 35 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index 1c928ab..dca4609 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -1796,7 +1796,7 @@ static void build_piix4_pci_hotplug(Aml *table)
>      aml_append(table, scope);
>  }
>  
> -static Aml *build_q35_osc_method(void)
> +static void build_q35_osc_method(Aml *dev)
>  {
>      Aml *if_ctx;
>      Aml *if_ctx2;
> @@ -1805,7 +1805,35 @@ static Aml *build_q35_osc_method(void)
>      Aml *a_cwd1 = aml_name("CDW1");
>      Aml *a_ctrl = aml_name("CTRL");
>  
> -    method = aml_method("_OSC", 4, AML_NOTSERIALIZED);
> +    /*
> +     * Bits defined in the Support Field provide information
> +     * regarding OS supported features.
> +     *
> +     * This field is not actually used and can be removed,
> +     * however it appears even if unused on most DSDTs.
> +     *
> +     * See:
> +     *     Table 6-148 Interpretation of _OSC Support Field,
> +     *     Passed in via Arg2, APCI 5.0
it's 2nd dword in Arg3

with this fixed 
Reviewed-by: Igor Mammedov <address@hidden>


> +     */
> +    aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> +
> +    /*
> +     * Bits defined in the Control Field are used to submit
> +     * request by the OS for control/handling of the associated feature
> +     *
> +     * See: Table 6-149 Interpretation of _OSC Control Field,
> +     *      Passed in via Arg3, ACPI 5.0
> +     *      Table 6-150 Interpretation of _OSC Control Field,
> +     *      Returned Value, APCI 5.0
> +     */
> +    aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
> +
> +
> +
> +   /*
> +    * 6.2.10 _OSC (Operating System Capabilities), APCI 5.0
> +    */
> +    method = aml_method("_OSC", 4, AML_SERIALIZED);
>      aml_append(method, aml_create_dword_field(aml_arg(3), aml_int(0), 
> "CDW1"));
>  
>      if_ctx = aml_if(aml_equal(
> @@ -1842,7 +1870,7 @@ static Aml *build_q35_osc_method(void)
>      aml_append(method, else_ctx);
>  
>      aml_append(method, aml_return(aml_arg(3)));
> -    return method;
> +    aml_append(dev, method);
>  }
>  
>  static void
> @@ -1898,9 +1926,7 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>          aml_append(dev, aml_name_decl("_CID", aml_eisaid("PNP0A03")));
>          aml_append(dev, aml_name_decl("_ADR", aml_int(0)));
>          aml_append(dev, aml_name_decl("_UID", aml_int(1)));
> -        aml_append(dev, aml_name_decl("SUPP", aml_int(0)));
> -        aml_append(dev, aml_name_decl("CTRL", aml_int(0)));
> -        aml_append(dev, build_q35_osc_method());
> +        build_q35_osc_method(dev);
>          aml_append(sb_scope, dev);
>          aml_append(dsdt, sb_scope);
>  
> @@ -1964,6 +1990,9 @@ build_dsdt(GArray *table_data, BIOSLinker *linker,
>              aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
>              aml_append(dev, aml_name_decl("_HID", aml_eisaid("PNP0A03")));
>              aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
> +            if (pci_bus_is_express(bus)) {
> +                build_q35_osc_method(dev);
> +            }
>  
>              if (numa_node != NUMA_NODE_UNASSIGNED) {
>                  aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));