Re: [PATCH] hw/pci/pcie: Forbid hot-plug via QMP if it's disabled on the slot

[Julia Suvorova]

On Tue, Apr 14, 2020 at 10:07 AM Marcel Apfelbaum
<address@hidden> wrote:
>
> Hi Julia,
>
> On 4/7/20 5:50 PM, Julia Suvorova wrote:
> > Raise an error when trying to hot-plug/unplug a device through QMP to a 
> > device
> > with disabled hot-plug capability. This makes the device behaviour more
> > consistent and provides an explanation of the failure in the case of
> > asynchronous unplug.
> >
> > Signed-off-by: Julia Suvorova <address@hidden>
> > ---
> >   hw/pci/pcie.c | 24 +++++++++++++++++++++---
> >   1 file changed, 21 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > index 0eb3a2a5d2..e9798caa8a 100644
> > --- a/hw/pci/pcie.c
> > +++ b/hw/pci/pcie.c
> > @@ -415,6 +415,7 @@ void pcie_cap_slot_plug_cb(HotplugHandler *hotplug_dev, 
> > DeviceState *dev,
> >   {
> >       PCIDevice *hotplug_pdev = PCI_DEVICE(hotplug_dev);
> >       uint8_t *exp_cap = hotplug_pdev->config + hotplug_pdev->exp.exp_cap;
> > +    uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
> >       PCIDevice *pci_dev = PCI_DEVICE(dev);
> >
> >       /* Don't send event when device is enabled during qemu machine 
> > creation:
> > @@ -430,6 +431,13 @@ void pcie_cap_slot_plug_cb(HotplugHandler 
> > *hotplug_dev, DeviceState *dev,
> >           return;
> >       }
> >
> > +    /* Hot-plug is disabled on the slot */
> > +    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> > +        error_setg(errp, "Device '%s' does not support hot-plug",
> > +                         DEVICE(hotplug_dev)->id);
> > +        return;
> > +    }
> > +
> >       /* To enable multifunction hot-plug, we just ensure the function
> >        * 0 added last. When function 0 is added, we set the sltsta and
> >        * inform OS via event notification.
> > @@ -464,14 +472,24 @@ static void pcie_unplug_device(PCIBus *bus, PCIDevice 
> > *dev, void *opaque)
> >       object_unparent(OBJECT(dev));
> >   }
> >
> > -void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
> > +void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_handler,
> >                                        DeviceState *dev, Error **errp)
> >   {
> >       Error *local_err = NULL;
> >       PCIDevice *pci_dev = PCI_DEVICE(dev);
> >       PCIBus *bus = pci_get_bus(pci_dev);
> > +    PCIDevice *hotplug_dev = PCI_DEVICE(hotplug_handler);
> > +    uint8_t *exp_cap = hotplug_dev->config + hotplug_dev->exp.exp_cap;
> > +    uint32_t sltcap = pci_get_word(exp_cap + PCI_EXP_SLTCAP);
> > +
> > +    /* Hot-unplug is disabled on the slot */
> > +    if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> > +        error_setg(errp, "Device '%s' does not support hot-unplug",
> > +                         DEVICE(hotplug_dev)->id);
> > +        return;
> > +    }
>
> Since this chunk appears twice I would consider refactoring it into
> a helper function. (I see the error message is different, but I suppose
> it can be tweaked)

Okay.

> >
> > -    pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, &local_err);
> > +    pcie_cap_slot_plug_common(hotplug_dev, dev, &local_err);
>
> It doesn't seems related to this patch.
>
> >       if (local_err) {
> >           error_propagate(errp, local_err);
> >           return;
> > @@ -490,7 +508,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler 
> > *hotplug_dev,
> >           return;
> >       }
> >
> > -    pcie_cap_slot_push_attention_button(PCI_DEVICE(hotplug_dev));
> > +    pcie_cap_slot_push_attention_button(hotplug_dev);
>
> Same here, maybe you can split it in 2 patches.

Yes, but it doesn't make sense by itself. Just cleaning necessary with
a new variable introduced.

Best regards, Julia Suvorova.