Re: [PATCH] microvm: turn off io reservations for pcie root ports

[Michael S. Tsirkin]

On Fri, Jun 03, 2022 at 10:59:20AM +0200, Gerd Hoffmann wrote:
> The pcie host bridge has no io window on microvm,
> so io reservations will not work.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

I don't much like overriding user like this. We end up users
setting it to silly values and then if we do want to
support this things just break. Thoughts?

> ---
>  hw/i386/microvm.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> 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 = {
> -- 
> 2.36.1