Re: [PATCH] hw/pci/pci: Fix slot check for plugged devices

[Julia Suvorova]

On Wed, Sep 23, 2020 at 5:03 PM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Wed, Sep 23, 2020 at 11:26:36AM +0200, Julia Suvorova wrote:
> > If devfn is assigned automatically, 'else' clauses will never be
> > executed. And if it does not matter for the reserved and available
> > devfn, because we have already checked it, the check for function0
> > needs to be done again.
> >
> > Signed-off-by: Julia Suvorova <jusual@redhat.com>
>
> This is just cosmetics right? I wouldn't describe this as
> a "fix" then - "simplify" would be clearer.

No, this is a bug fix. For example, if you had a root port with a
device on it already, and you do
'device_add new_device,bus=the_same_root_port', then it will miss the
last 'if' and will be added to slot 1.

> > ---
> >  hw/pci/pci.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> > index de0fae10ab..ae132b0b52 100644
> > --- a/hw/pci/pci.c
> > +++ b/hw/pci/pci.c
> > @@ -1034,8 +1034,9 @@ static PCIDevice *do_pci_register_device(PCIDevice 
> > *pci_dev,
> >                     PCI_SLOT(devfn), PCI_FUNC(devfn), name,
> >                     bus->devices[devfn]->name);
> >          return NULL;
> > -    } else if (dev->hotplugged &&
> > -               pci_get_function_0(pci_dev)) {
> > +    };
> > +
> > +    if (dev->hotplugged && pci_get_function_0(pci_dev)) {
> >          error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"
> >                     " new func %s cannot be exposed to guest.",
> >                     PCI_SLOT(pci_get_function_0(pci_dev)->devfn),
> > --
> > 2.25.4
>