Kdump could fail sometime on Hyper-V guest over Accelerated Network
interface. This is because the retry in hv_pci_enter_d0() releases
child device strurctures in hv_pci_bus_exit(). Although there is
a second asynchronous device relations message sending from the host,
if this message arrives guest after hv_send_resource_allocated() is
called, the retry would fail.
Fix the problem by moving retry to hv_pci_probe() and starting retry
from hv_pci_query_relations() call. This will cause a device relations
message to arrive guest synchronously. The guest would be able to
rebuild the child device structures before calling
hv_send_resource_allocated().
This problem only happens on Accelerated Network or SRIOV devices as
only such devices currently are attached under vmbus PCI bridge.
Fixes: c81992e7f4aa ("PCI: hv: Retry PCI bus D0 entry on invalid device state")
Signed-off-by: Wei Hu <weh@xxxxxxxxxxxxx>
Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
---
v2: Adding Fixes tag according to Michael Kelley's review comment.
v3: Fix couple typos and reword commit message to make it clearer.
Thanks the comments from Bjorn Helgaas.
v4: Adding more problem descritpions in the commit message
and code upon request from Lorenze Pieralisi.
drivers/pci/controller/pci-hyperv.c | 71 +++++++++++++++--------------
1 file changed, 37 insertions(+), 34 deletions(-)
diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index bf40ff09c99d..d1758986fbc9 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 +3145,47 @@ 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.
+ * Since the hv_pci_bus_exit() call releases structures
+ * of all its child devices, we need to start the retry from
+ * hv_pci_query_relations() call, requesting host to send
+ * the synchronous child device relations message before this
+ * information is needed in hv_send_resources_allocated()
+ * call later .
+ */
+ 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
