Revert "PCI: hv: Fix a timing issue which causes kdump to fail occasionally"

commit a847234e24d03d01a9566d1d9dcce018cc018d67 upstream.

This reverts commit d6af2ed29c7c1c311b96dac989dcb991e90ee195.

The statement "the hv_pci_bus_exit() call releases structures of all its
child devices" in commit d6af2ed29c7c is not true: in the path
hv_pci_probe() -> hv_pci_enter_d0() -> hv_pci_bus_exit(hdev, true): the
parameter "keep_devs" is true, so hv_pci_bus_exit() does *not* release the
child "struct hv_pci_dev *hpdev" that is created earlier in
pci_devices_present_work() -> new_pcichild_device().

The commit d6af2ed29c7c was originally made in July 2020 for RHEL 7.7,
where the old version of hv_pci_bus_exit() was used; when the commit was
rebased and merged into the upstream, people didn't notice that it's
not really necessary. The commit itself doesn't cause any issue, but it
makes hv_pci_probe() more complicated. Revert it to facilitate some
upcoming changes to hv_pci_probe().

Signed-off-by: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Acked-by: Wei Hu <weh@microsoft.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20230615044451.5580-5-decui@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 115910e..3c3c325 100644 (file)
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3251,8 +3251,10 @@ 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
@@ -3279,6 +3281,38 @@ 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",
@@ -3524,7 +3558,6 @@ 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;
 
        /*
@@ -3664,47 +3697,11 @@ 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;