Drivers: hv: vmbus: Log on missing offers if any

When resuming from hibernation, log any channels that were present
before hibernation but now are gone.
In general, the boot-time devices configured for a resuming VM should be
the same as the devices in the VM at the time of hibernation. It's
uncommon for the configuration to have been changed such that offers
are missing. Changing the configuration violates the rules for
hibernation anyway.
The cleanup of missing channels is not straight-forward and dependent
on individual device driver functionality and implementation,
so it can be added in future with separate changes.

Signed-off-by: John Starks <jostarks@microsoft.com>
Co-developed-by: Naman Jain <namjain@linux.microsoft.com>
Signed-off-by: Naman Jain <namjain@linux.microsoft.com>
Reviewed-by: Easwar Hariharan <eahariha@linux.microsoft.com>
Reviewed-by: Saurabh Sengar <ssengar@linux.microsoft.com>
Reviewed-by: Michael Kelley <mhklinux@outlook.com>
Link: https://lore.kernel.org/r/20250102130712.1661-3-namjain@linux.microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
Message-ID: <20250102130712.1661-3-namjain@linux.microsoft.com>

drivers/hv/vmbus_drv.c

@@ -2462,6 +2462,7 @@ static int vmbus_bus_suspend(struct device *dev)
 
 static int vmbus_bus_resume(struct device *dev)
 {
+	struct vmbus_channel *channel;
 	struct vmbus_channel_msginfo *msginfo;
 	size_t msgsize;
 	int ret;
@@ -2494,6 +2495,22 @@ static int vmbus_bus_resume(struct device *dev)
 
 	vmbus_request_offers();
 
+	mutex_lock(&vmbus_connection.channel_mutex);
+	list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
+		if (channel->offermsg.child_relid != INVALID_RELID)
+			continue;
+
+		/* hvsock channels are not expected to be present. */
+		if (is_hvsock_channel(channel))
+			continue;
+
+		pr_err("channel %pUl/%pUl not present after resume.\n",
+		       &channel->offermsg.offer.if_type,
+		       &channel->offermsg.offer.if_instance);
+		/* ToDo: Cleanup these channels here */
+	}
+	mutex_unlock(&vmbus_connection.channel_mutex);
+
 	/* Reset the event for the next suspend. */
 	reinit_completion(&vmbus_connection.ready_for_suspend_event);