Re: [PATCH 1/1] pci/pcie: refuse another hotplug/unplug event if attention button is pending

[Igor Mammedov]

On Wed, 29 Jul 2020 08:09:37 +0300
Maxim Levitsky <mlevitsk@redhat.com> wrote:

> On Wed, 2020-07-22 at 19:19 +0300, Maxim Levitsky wrote:
> > On Wed, 2020-07-22 at 19:17 +0300, Maxim Levitsky wrote:  
> > > Curently it is possible to hotplug a device and then immediatly
> > > hotunplug it before the OS notices, and that will result
> > > in missed unplug event since we can only send one attention button event.
> > > 
> > > Moreover the device will stuck in unplugging state forever.
> > > 
> > > Error out in such cases and rely on the caller (e.g libvirt) to retry
> > > the unplug a bit later
> > > 
> > > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> > > ---
> > >  hw/pci/pcie.c | 11 +++++++++++
> > >  1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > > index 5b48bae0f6..9e836cf2f4 100644
> > > --- a/hw/pci/pcie.c
> > > +++ b/hw/pci/pcie.c
> > > @@ -402,6 +402,17 @@ static void pcie_cap_slot_plug_common(PCIDevice 
> > > *hotplug_dev, DeviceState *dev,
> > >           */
> > >          error_setg_errno(errp, EBUSY, "slot is electromechanically 
> > > locked");
> > >      }
> > > +
> > > +    if (sltsta & PCI_EXP_SLTSTA_ABP) {
> > > +        /*
> > > +         * Attention button is pressed, thus we can't send another
> > > +         * hotpplug event  
> > Typo here, forgot to refresh the commit.  
> > > +         */
> > > +        error_setg_errno(errp, EBUSY,
> > > +                         "attention button is already pressed, can't "
> > > +                         "send another hotplug event");
> > > +    }
> > > +
> > >  }
> > >  
> > >  void pcie_cap_slot_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState 
> > > *dev,  
> ping.

CCing Julia since she was looking into PCI hotplug/unplug code recently.

> 
> Best regards,
>       Maxim Levitsky
> 
>