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

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2182619

commit a847234
Author: Dexuan Cui <decui@microsoft.com>
Date:   Wed Jun 14 21:44:50 2023 -0700

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

    This reverts commit d6af2ed.

    The statement "the hv_pci_bus_exit() call releases structures of all its
    child devices" in commit d6af2ed 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    The commit d6af2ed was originally made in July 2020 for RHEL 7.7,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: Vitaly Kuznetsov <vkuznets@redhat.com>

Author: vittyvk

drivers/pci/controller/pci-hyperv.c

@@ -3225,8 +3225,10 @@ 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
@@ -3253,6 +3255,38 @@ 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",
@@ -3498,7 +3532,6 @@ 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;
 
 	/*
@@ -3638,47 +3671,11 @@ 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;