Re: [PATCH] Fix a gap where acpi_pcihp_find_hotplug_bus() returns a non-hotpluggable bus

[Ani Sinha]

On Thu, Sep 3, 2020 at 3:46 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Thu, Sep 03, 2020 at 03:41:13PM +0530, Ani Sinha wrote:
> > On Sep 3, 2020, 15:35 +0530, Michael S. Tsirkin <mst@redhat.com>, wrote:
> >
> >     On Sat, Aug 29, 2020 at 01:42:33PM +0530, Ani Sinha wrote:
> >
> >         When ACPI hotplug for the root bus is disabled, the bsel property 
> > for
> >         that
> >
> >         bus is not set. Please see the following commit:
> >
> >
> >
> >         3d7e78aa7777f ("Introduce a new flag for i440fx to disable PCI 
> > hotplug
> >         on the root bus").
> >
> >
> >
> >         As a result, when acpi_pcihp_find_hotplug_bus() is called
> >
> >         with bsel set to 0, it may return the root bus. This would be wrong
> >         since the
> >
> >         root bus is not hotpluggable. In general, this can potentially 
> > happen
> >         to other
> >
> >         buses as well.
> >
> >         In this patch, we fix the issue in this function by checking if the 
> > bus
> >         returned
> >
> >         by the function is actually hotpluggable. If not, we simply return
> >         NULL. This
> >
> >         avoids the scenario where we are actually returning a 
> > non-hotpluggable
> >         bus.
> >
> >
> >
> >         Signed-off-by: Ani Sinha <ani@anisinha.ca>
> >
> >
> >
> >     What exactly are the consequences though?
> >
> >
> > The root bus might get ejected by the user when it should not if the user 
> > does
> > the following:
> >
> > outl 0xae10 0
> > outl 0xae08 your_slot
> >
> > Please see Julia’s comment:
> > https://www.mail-archive.com/qemu-devel@nongnu.org/msg734548.html
>
> OK so patch looks good, but please add all this in the commit log.

Done. V2 sent.