Re: [edk2-devel] [PATCH v7 1/6] MdeModulePkg/PciHostBridge: io range is not mandatory

["Ard Biesheuvel" <ardb@kernel.org>]

On Fri, 3 Jun 2022 at 10:29, Gerd Hoffmann <kraxel@redhat.com> wrote:
>
>   Hi,
>
> > This seems to be related to the padding logic, i.e., we are trying to
> > preserve some extra I/O space for the root port in case we hotplug
> > something that might need it.
>
> > --- a/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > +++ b/OvmfPkg/PciHotPlugInitDxe/PciHotPlugInit.c
> > @@ -733,7 +733,7 @@ GetResourcePadding (
> >      }
> >    }
> >
> > -  if (DefaultIo) {
> > +  if (DefaultIo && FALSE) {
> >      //
> >      // Request defaults.
> >      //
>
> Oh, *there* it comes from.  Given this is configurable already we can
> fix that one in qemu with a microvm tweak:
>
> diff --git a/hw/i386/microvm.c b/hw/i386/microvm.c
> index 4b3b1dd262f1..f01d972f5d28 100644
> --- a/hw/i386/microvm.c
> +++ b/hw/i386/microvm.c
> @@ -757,6 +757,12 @@ static void microvm_class_init(ObjectClass *oc, void *data)
>          "Set off to disable adding virtio-mmio devices to the kernel cmdline");
>
>      machine_class_allow_dynamic_sysbus_dev(mc, TYPE_RAMFB_DEVICE);
> +
> +    /*
> +     * pcie host bridge (gpex) on microvm has no io address window,
> +     * so reserving io space is not going to work.  Turn it off.
> +     */
> +    object_register_sugar_prop("pcie-root-port", "io-reserve", "0", true);
>  }
>
>  static const TypeInfo microvm_machine_info = {
>
> So, I think we can drop patch #1.  Want me respin the series, or can you
> simply drop the patch on merge?
>

I've already queued it up.