[PATCH 2/4] PCI: hv: Add the support of hibernation

[Dexuan Cui <decui@microsoft.com>]

Implement the suspend/resume callbacks for hibernation.

hv_pci_suspend() needs to prevent any new work from being queued: a later
patch will address this issue.

Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/pci/controller/pci-hyperv.c | 76 +++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 03fa039..3b77a3a 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1398,6 +1398,23 @@ static void prepopulate_bars(struct hv_pcibus_device *hbus)
 
 	spin_lock_irqsave(&hbus->device_list_lock, flags);
 
+	/*
+	 * Clear the memory enable bit, in case it's already set. This occurs
+	 * in the suspend path of hibernation, where the device is suspended,
+	 * resumed and suspended again: see hibernation_snapshot() and
+	 * hibernation_platform_enter().
+	 *
+	 * If the memory enable bit is already set, Hyper-V sliently ignores
+	 * the below BAR updates, and the related PCI device driver can not
+	 * work, because reading from the device register(s) always returns
+	 * 0xFFFFFFFF.
+	 */
+	list_for_each_entry(hpdev, &hbus->children, list_entry) {
+		_hv_pcifront_read_config(hpdev, PCI_COMMAND, 2, &command);
+		command &= ~PCI_COMMAND_MEMORY;
+		_hv_pcifront_write_config(hpdev, PCI_COMMAND, 2, command);
+	}
+
 	/* Pick addresses for the BARs. */
 	do {
 		list_for_each_entry(hpdev, &hbus->children, list_entry) {
@@ -2737,6 +2754,63 @@ static int hv_pci_remove(struct hv_device *hdev)
 	return ret;
 }
 
+static int hv_pci_suspend(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	int ret;
+
+	/* XXX: Need to prevent any new work from being queued. */
+	flush_workqueue(hbus->wq);
+
+	ret = hv_pci_bus_exit(hdev, true);
+	if (ret)
+		return ret;
+
+	vmbus_close(hdev->channel);
+
+	return 0;
+}
+
+static int hv_pci_resume(struct hv_device *hdev)
+{
+	struct hv_pcibus_device *hbus = hv_get_drvdata(hdev);
+	enum pci_protocol_version_t version[1];
+	int ret;
+
+	hbus->state = hv_pcibus_init;
+
+	ret = vmbus_open(hdev->channel, pci_ring_size, pci_ring_size, NULL, 0,
+			 hv_pci_onchannelcallback, hbus);
+	if (ret)
+		return ret;
+
+	/* Only use the version that was in use before hibernation. */
+	version[0] = pci_protocol_version;
+	ret = hv_pci_protocol_negotiation(hdev, version, 1);
+	if (ret)
+		goto out;
+
+	ret = hv_pci_query_relations(hdev);
+	if (ret)
+		goto out;
+
+	ret = hv_pci_enter_d0(hdev);
+	if (ret)
+		goto out;
+
+	ret = hv_send_resources_allocated(hdev);
+	if (ret)
+		goto out;
+
+	prepopulate_bars(hbus);
+
+	hbus->state = hv_pcibus_installed;
+	return 0;
+out:
+	vmbus_close(hdev->channel);
+	return ret;
+}
+
 static const struct hv_vmbus_device_id hv_pci_id_table[] = {
 	/* PCI Pass-through Class ID */
 	/* 44C4F61D-4444-4400-9D52-802E27EDE19F */
@@ -2751,6 +2825,8 @@ static int hv_pci_remove(struct hv_device *hdev)
 	.id_table	= hv_pci_id_table,
 	.probe		= hv_pci_probe,
 	.remove		= hv_pci_remove,
+	.suspend	= hv_pci_suspend,
+	.resume		= hv_pci_resume,
 };
 
 static void __exit exit_hv_pci_drv(void)
-- 
1.8.3.1