From: Wei Hu <[email protected]> Sent: Thursday, July 16, 2020 8:51 AM > > Kdump could fail sometime on HyperV guest over Accerlated Network > interface. This is because the retry in hv_pci_enter_d0() relies on > an asynchronous host event to arrive guest before calling > hv_send_resources_allocated(). This fixes the problem by moving retry > to hv_pci_probe(), removing this dependence and making the calling > sequence synchronous. > > Signed-off-by: Wei Hu <[email protected]>
I'd suggest adding a "Fixes:" tag referencing commit c81992e7f4aa. Otherwise, Reviewed-by: Michael Kelley <[email protected]> > --- > drivers/pci/controller/pci-hyperv.c | 66 ++++++++++++++--------------- > 1 file changed, 32 insertions(+), 34 deletions(-) > > diff --git a/drivers/pci/controller/pci-hyperv.c > b/drivers/pci/controller/pci-hyperv.c > index bf40ff09c99d..738ee30f3334 100644 > --- a/drivers/pci/controller/pci-hyperv.c > +++ b/drivers/pci/controller/pci-hyperv.c > @@ -2759,10 +2759,8 @@ static int hv_pci_enter_d0(struct hv_device *hdev) > struct pci_bus_d0_entry *d0_entry; > struct hv_pci_compl comp_pkt; > struct pci_packet *pkt; > - bool retry = true; > int ret; > > -enter_d0_retry: > /* > * Tell the host that the bus is ready to use, and moved into the > * powered-on state. This includes telling the host which region > @@ -2789,38 +2787,6 @@ static int hv_pci_enter_d0(struct hv_device *hdev) > if (ret) > goto exit; > > - /* > - * In certain case (Kdump) the pci device of interest was > - * not cleanly shut down and resource is still held on host > - * side, the host could return invalid device status. > - * We need to explicitly request host to release the resource > - * and try to enter D0 again. > - */ > - if (comp_pkt.completion_status < 0 && retry) { > - retry = false; > - > - dev_err(&hdev->device, "Retrying D0 Entry\n"); > - > - /* > - * Hv_pci_bus_exit() calls hv_send_resource_released() > - * to free up resources of its child devices. > - * In the kdump kernel we need to set the > - * wslot_res_allocated to 255 so it scans all child > - * devices to release resources allocated in the > - * normal kernel before panic happened. > - */ > - hbus->wslot_res_allocated = 255; > - > - ret = hv_pci_bus_exit(hdev, true); > - > - if (ret == 0) { > - kfree(pkt); > - goto enter_d0_retry; > - } > - dev_err(&hdev->device, > - "Retrying D0 failed with ret %d\n", ret); > - } > - > if (comp_pkt.completion_status < 0) { > dev_err(&hdev->device, > "PCI Pass-through VSP failed D0 Entry with status %x\n", > @@ -3058,6 +3024,7 @@ static int hv_pci_probe(struct hv_device *hdev, > struct hv_pcibus_device *hbus; > u16 dom_req, dom; > char *name; > + bool enter_d0_retry = true; > int ret; > > /* > @@ -3178,11 +3145,42 @@ static int hv_pci_probe(struct hv_device *hdev, > if (ret) > goto free_fwnode; > > +retry: > ret = hv_pci_query_relations(hdev); > if (ret) > goto free_irq_domain; > > ret = hv_pci_enter_d0(hdev); > + /* > + * In certain case (Kdump) the pci device of interest was > + * not cleanly shut down and resource is still held on host > + * side, the host could return invalid device status. > + * We need to explicitly request host to release the resource > + * and try to enter D0 again. > + * The retry should start from hv_pci_query_relations() call. > + */ > + if (ret == -EPROTO && enter_d0_retry) { > + enter_d0_retry = false; > + > + dev_err(&hdev->device, "Retrying D0 Entry\n"); > + > + /* > + * Hv_pci_bus_exit() calls hv_send_resources_released() > + * to free up resources of its child devices. > + * In the kdump kernel we need to set the > + * wslot_res_allocated to 255 so it scans all child > + * devices to release resources allocated in the > + * normal kernel before panic happened. > + */ > + hbus->wslot_res_allocated = 255; > + ret = hv_pci_bus_exit(hdev, true); > + > + if (ret == 0) > + goto retry; > + > + dev_err(&hdev->device, > + "Retrying D0 failed with ret %d\n", ret); > + } > if (ret) > goto free_irq_domain; > > -- > 2.20.1
