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Re: [PATCH] hw/pci/pcie: Move hot plug capability check to pre_plug call
From: |
Julia Suvorova |
Subject: |
Re: [PATCH] hw/pci/pcie: Move hot plug capability check to pre_plug callback |
Date: |
Tue, 2 Jun 2020 09:16:40 +0200 |
On Tue, Jun 2, 2020 at 5:54 AM Michael S. Tsirkin <mst@redhat.com> wrote:
>
> On Mon, Jun 01, 2020 at 06:29:34PM +0200, Julia Suvorova wrote:
> > Check for hot plug capability earlier to avoid removing devices attached
> > during the initialization process.
> >
> > Run qemu with an unattached drive:
> > -drive file=$FILE,if=none,id=drive0 \
> > -device pcie-root-port,id=rp0,slot=3,bus=pcie.0,hotplug=off
> > Hotplug a block device:
> > device_add virtio-blk-pci,id=blk0,drive=drive0,bus=rp0
> > If hotplug fails on plug_cb, drive0 will be deleted.
> >
> > Signed-off-by: Julia Suvorova <jusual@redhat.com>
>
>
> Fixes: 0501e1aa1d32a6 ("hw/pci/pcie: Forbid hot-plug if it's disabled on the
> slot")
>
> correct?
Yes.
> > ---
> > Hard to say if it's a bug or generally acceptable behaviour, but seems like
> > hotplug_handler_plug should never fail.
> >
> > hw/pci/pcie.c | 19 +++++++++++--------
> > 1 file changed, 11 insertions(+), 8 deletions(-)
> >
> > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > index f50e10b8fb..5b9c022d91 100644
> > --- a/hw/pci/pcie.c
> > +++ b/hw/pci/pcie.c
> > @@ -407,6 +407,17 @@ static void pcie_cap_slot_plug_common(PCIDevice
> > *hotplug_dev, DeviceState *dev,
> > void pcie_cap_slot_pre_plug_cb(HotplugHandler *hotplug_dev, DeviceState
> > *dev,
> > Error **errp)
> > {
> > + 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);
> > +
> > + /* Check if hot-plug is disabled on the slot */
> > + if (dev->hotplugged && (sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> > + error_setg(errp, "Hot-plug failed: unsupported by the port device
> > '%s'",
> > + DEVICE(hotplug_pdev)->id);
> > + return;
> > + }
> > +
> > pcie_cap_slot_plug_common(PCI_DEVICE(hotplug_dev), dev, errp);
> > }
> >
> > @@ -415,7 +426,6 @@ 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:
> > @@ -431,13 +441,6 @@ void pcie_cap_slot_plug_cb(HotplugHandler
> > *hotplug_dev, DeviceState *dev,
> > return;
> > }
> >
> > - /* Check if hot-plug is disabled on the slot */
> > - if ((sltcap & PCI_EXP_SLTCAP_HPC) == 0) {
> > - error_setg(errp, "Hot-plug failed: unsupported by the port device
> > '%s'",
> > - DEVICE(hotplug_pdev)->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.
> > --
> > 2.25.4
>