Commit 788d2599 authored by Michael Roth's avatar Michael Roth Committed by David Gibson
Browse files

spapr_pci: fix multifunction hotplug 



Since 3f1e1478, QEMU has adopted a convention of supporting function
hotplug by deferring hotplug events until func 0 is hotplugged.
This is likely how management tools like libvirt would expose
such support going forward.

Since sPAPR guests rely on per-func events rather than
slot-based, our protocol has been to hotplug func 0 *first* to
avoid cases where devices appear within guests without func 0
present to avoid undefined behavior.

To remain compatible with new convention, defer hotplug in a
similar manner, but then generate events in 0-first order as we
did in the past. Once func 0 present, fail any attempts to plug
additional functions (as we do with PCIe).

For unplug, defer unplug operations in a similar manner, but
generate unplug events such that function 0 is removed last in guest.

Signed-off-by: default avatarMichael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: default avatarDavid Gibson <david@gibson.dropbear.id.au>
parent a88dced8

hw/ppc/spapr_pci.c

+86 −7
Original line number Diff line number Diff line
@@ -1142,14 +1142,21 @@ static void spapr_phb_remove_pci_device(sPAPRDRConnector *drc, 
    drck->detach(drc, DEVICE(pdev), spapr_phb_remove_pci_device_cb, phb, errp);

}



static sPAPRDRConnector *spapr_phb_get_pci_drc(sPAPRPHBState *phb,

                                               PCIDevice *pdev)

static sPAPRDRConnector *spapr_phb_get_pci_func_drc(sPAPRPHBState *phb,

                                                    uint32_t busnr,

                                                    int32_t devfn)

{

    uint32_t busnr = pci_bus_num(PCI_BUS(qdev_get_parent_bus(DEVICE(pdev))));

    return spapr_dr_connector_by_id(SPAPR_DR_CONNECTOR_TYPE_PCI,

                                    (phb->index << 16) |

                                    (busnr << 8) |

                                    pdev->devfn);

                                    devfn);

}



static sPAPRDRConnector *spapr_phb_get_pci_drc(sPAPRPHBState *phb,

                                               PCIDevice *pdev)

{

    uint32_t busnr = pci_bus_num(PCI_BUS(qdev_get_parent_bus(DEVICE(pdev))));

    return spapr_phb_get_pci_func_drc(phb, busnr, pdev->devfn);

}



static uint32_t spapr_phb_get_pci_drc_index(sPAPRPHBState *phb,
@@ -1173,6 +1180,8 @@ static void spapr_phb_hot_plug_child(HotplugHandler *plug_handler, 
    PCIDevice *pdev = PCI_DEVICE(plugged_dev);

    sPAPRDRConnector *drc = spapr_phb_get_pci_drc(phb, pdev);

    Error *local_err = NULL;

    PCIBus *bus = PCI_BUS(qdev_get_parent_bus(DEVICE(pdev)));

    uint32_t slotnr = PCI_SLOT(pdev->devfn);



    /* if DR is disabled we don't need to do anything in the case of

     * hotplug or coldplug callbacks
@@ -1190,13 +1199,44 @@ static void spapr_phb_hot_plug_child(HotplugHandler *plug_handler, 


    g_assert(drc);



    /* Following the QEMU convention used for PCIe multifunction

     * hotplug, we do not allow functions to be hotplugged to a

     * slot that already has function 0 present

     */

    if (plugged_dev->hotplugged && bus->devices[PCI_DEVFN(slotnr, 0)] &&

        PCI_FUNC(pdev->devfn) != 0) {

        error_setg(errp, "PCI: slot %d function 0 already ocuppied by %s,"

                   " additional functions can no longer be exposed to guest.",

                   slotnr, bus->devices[PCI_DEVFN(slotnr, 0)]->name);

        return;

    }



    spapr_phb_add_pci_device(drc, phb, pdev, &local_err);

    if (local_err) {

        error_propagate(errp, local_err);

        return;

    }

    if (plugged_dev->hotplugged) {

        spapr_hotplug_req_add_by_index(drc);



    /* If this is function 0, signal hotplug for all the device functions.

     * Otherwise defer sending the hotplug event.

     */

    if (plugged_dev->hotplugged && PCI_FUNC(pdev->devfn) == 0) {

        int i;



        for (i = 0; i < 8; i++) {

            sPAPRDRConnector *func_drc;

            sPAPRDRConnectorClass *func_drck;

            sPAPRDREntitySense state;



            func_drc = spapr_phb_get_pci_func_drc(phb, pci_bus_num(bus),

                                                  PCI_DEVFN(slotnr, i));

            func_drck = SPAPR_DR_CONNECTOR_GET_CLASS(func_drc);

            func_drck->entity_sense(func_drc, &state);



            if (state == SPAPR_DR_ENTITY_SENSE_PRESENT) {

                spapr_hotplug_req_add_by_index(func_drc);

            }

        }

    }

}
@@ -1219,12 +1259,51 @@ static void spapr_phb_hot_unplug_child(HotplugHandler *plug_handler, 


    drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);

    if (!drck->release_pending(drc)) {

        PCIBus *bus = PCI_BUS(qdev_get_parent_bus(DEVICE(pdev)));

        uint32_t slotnr = PCI_SLOT(pdev->devfn);

        sPAPRDRConnector *func_drc;

        sPAPRDRConnectorClass *func_drck;

        sPAPRDREntitySense state;

        int i;



        /* ensure any other present functions are pending unplug */

        if (PCI_FUNC(pdev->devfn) == 0) {

            for (i = 1; i < 8; i++) {

                func_drc = spapr_phb_get_pci_func_drc(phb, pci_bus_num(bus),

                                                      PCI_DEVFN(slotnr, i));

                func_drck = SPAPR_DR_CONNECTOR_GET_CLASS(func_drc);

                func_drck->entity_sense(func_drc, &state);

                if (state == SPAPR_DR_ENTITY_SENSE_PRESENT

                    && !func_drck->release_pending(func_drc)) {

                    error_setg(errp,

                               "PCI: slot %d, function %d still present. "

                               "Must unplug all non-0 functions first.",

                               slotnr, i);

                    return;

                }

            }

        }



        spapr_phb_remove_pci_device(drc, phb, pdev, &local_err);

        if (local_err) {

            error_propagate(errp, local_err);

            return;

        }

        spapr_hotplug_req_remove_by_index(drc);



        /* if this isn't func 0, defer unplug event. otherwise signal removal

         * for all present functions

         */

        if (PCI_FUNC(pdev->devfn) == 0) {

            for (i = 7; i >= 0; i--) {

                func_drc = spapr_phb_get_pci_func_drc(phb, pci_bus_num(bus),

                                                      PCI_DEVFN(slotnr, i));

                func_drck = SPAPR_DR_CONNECTOR_GET_CLASS(func_drc);

                func_drck->entity_sense(func_drc, &state);

                if (state == SPAPR_DR_ENTITY_SENSE_PRESENT) {

                    spapr_hotplug_req_remove_by_index(func_drc);

                }

            }

        }

    }

}