Drivers: hv: balloon: Add logging for dynamic memory operations

Added logging to help troubleshoot common ballooning, hot add,
and versioning issues.
Signed-off-by: Alex Ng <alexng@microsoft.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/hv/hv_balloon.c

@@ -564,6 +564,11 @@ struct hv_dynmem_device {
 	 * next version to try.
 	 */
 	__u32 next_version;
+
+	/*
+	 * The negotiated version agreed by host.
+	 */
+	__u32 version;
 };
 
 static struct hv_dynmem_device dm_device;
@@ -645,6 +650,7 @@ static void hv_bring_pgs_online(struct hv_hotadd_state *has,
 {
 	int i;
 
+	pr_debug("Online %lu pages starting at pfn 0x%lx\n", size, start_pfn);
 	for (i = 0; i < size; i++)
 		hv_page_online_one(has, pfn_to_page(start_pfn + i));
 }
@@ -685,7 +691,7 @@ static void hv_mem_hot_add(unsigned long start, unsigned long size,
 				(HA_CHUNK << PAGE_SHIFT));
 
 		if (ret) {
-			pr_info("hot_add memory failed error is %d\n", ret);
+			pr_warn("hot_add memory failed error is %d\n", ret);
 			if (ret == -EEXIST) {
 				/*
 				 * This error indicates that the error
@@ -814,6 +820,9 @@ static unsigned long handle_pg_range(unsigned long pg_start,
 	unsigned long old_covered_state;
 	unsigned long res = 0, flags;
 
+	pr_debug("Hot adding %lu pages starting at pfn 0x%lx.\n", pg_count,
+		pg_start);
+
 	spin_lock_irqsave(&dm_device.ha_lock, flags);
 	list_for_each_entry(has, &dm_device.ha_region_list, list) {
 		/*
@@ -1196,8 +1205,6 @@ static unsigned int alloc_balloon_pages(struct hv_dynmem_device *dm,
 	return num_pages;
 }
 
-
-
 static void balloon_up(struct work_struct *dummy)
 {
 	unsigned int num_pages = dm_device.balloon_wrk.num_pages;
@@ -1224,6 +1231,10 @@ static void balloon_up(struct work_struct *dummy)
 
 	/* Refuse to balloon below the floor, keep the 2M granularity. */
 	if (avail_pages < num_pages || avail_pages - num_pages < floor) {
+		pr_warn("Balloon request will be partially fulfilled. %s\n",
+			avail_pages < num_pages ? "Not enough memory." :
+			"Balloon floor reached.");
+
 		num_pages = avail_pages > floor ? (avail_pages - floor) : 0;
 		num_pages -= num_pages % PAGES_IN_2M;
 	}
@@ -1245,6 +1256,9 @@ static void balloon_up(struct work_struct *dummy)
 		}
 
 		if (num_ballooned == 0 || num_ballooned == num_pages) {
+			pr_debug("Ballooned %u out of %u requested pages.\n",
+				num_pages, dm_device.balloon_wrk.num_pages);
+
 			bl_resp->more_pages = 0;
 			done = true;
 			dm_device.state = DM_INITIALIZED;
@@ -1292,12 +1306,16 @@ static void balloon_down(struct hv_dynmem_device *dm,
 	int range_count = req->range_count;
 	struct dm_unballoon_response resp;
 	int i;
+	unsigned int prev_pages_ballooned = dm->num_pages_ballooned;
 
 	for (i = 0; i < range_count; i++) {
 		free_balloon_pages(dm, &range_array[i]);
 		complete(&dm_device.config_event);
 	}
 
+	pr_debug("Freed %u ballooned pages.\n",
+		prev_pages_ballooned - dm->num_pages_ballooned);
+
 	if (req->more_pages == 1)
 		return;
 
@@ -1365,6 +1383,7 @@ static void version_resp(struct hv_dynmem_device *dm,
 	version_req.hdr.size = sizeof(struct dm_version_request);
 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
 	version_req.version.version = dm->next_version;
+	dm->version = version_req.version.version;
 
 	/*
 	 * Set the next version to try in case current version fails.
@@ -1557,6 +1576,7 @@ static int balloon_probe(struct hv_device *dev,
 	version_req.hdr.trans_id = atomic_inc_return(&trans_id);
 	version_req.version.version = DYNMEM_PROTOCOL_VERSION_WIN10;
 	version_req.is_last_attempt = 0;
+	dm_device.version = version_req.version.version;
 
 	ret = vmbus_sendpacket(dev->channel, &version_req,
 				sizeof(struct dm_version_request),
@@ -1579,6 +1599,11 @@ static int balloon_probe(struct hv_device *dev,
 		ret = -ETIMEDOUT;
 		goto probe_error2;
 	}
+
+	pr_info("Using Dynamic Memory protocol version %u.%u\n",
+		DYNMEM_MAJOR_VERSION(dm_device.version),
+		DYNMEM_MINOR_VERSION(dm_device.version));
+
 	/*
 	 * Now submit our capabilities to the host.
 	 */