Commit e3ede02a authored by Dexuan Cui's avatar Dexuan Cui Committed by Sasha Levin
Browse files

Drivers: hv: vmbus: Ignore the offers when resuming from hibernation 



When the VM resumes, the host re-sends the offers. We should not add the
offers to the global vmbus_connection.chn_list again.

This patch assumes the RELIDs of the channels don't change across
hibernation. Actually this is not always true, especially in the case of
NIC SR-IOV the VF vmbus device's RELID sometimes can change. A later patch
will address this issue by mapping the new offers to the old channels and
fixing up the old channels, if necessary.

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 271b2224

drivers/hv/channel_mgmt.c

+57 −1
Original line number Diff line number Diff line
@@ -847,6 +847,37 @@ void vmbus_initiate_unload(bool crash) 
		vmbus_wait_for_unload();

}



/*

 * find_primary_channel_by_offer - Get the channel object given the new offer.

 * This is only used in the resume path of hibernation.

 */

static struct vmbus_channel *

find_primary_channel_by_offer(const struct vmbus_channel_offer_channel *offer)

{

	struct vmbus_channel *channel = NULL, *iter;

	const guid_t *inst1, *inst2;



	/* Ignore sub-channel offers. */

	if (offer->offer.sub_channel_index != 0)

		return NULL;



	mutex_lock(&vmbus_connection.channel_mutex);



	list_for_each_entry(iter, &vmbus_connection.chn_list, listentry) {

		inst1 = &iter->offermsg.offer.if_instance;

		inst2 = &offer->offer.if_instance;



		if (guid_equal(inst1, inst2)) {

			channel = iter;

			break;

		}

	}



	mutex_unlock(&vmbus_connection.channel_mutex);



	return channel;

}



/*

 * vmbus_onoffer - Handler for channel offers from vmbus in parent partition.

 *
@@ -854,12 +885,37 @@ void vmbus_initiate_unload(bool crash) 
static void vmbus_onoffer(struct vmbus_channel_message_header *hdr)

{

	struct vmbus_channel_offer_channel *offer;

	struct vmbus_channel *newchannel;

	struct vmbus_channel *oldchannel, *newchannel;

	size_t offer_sz;



	offer = (struct vmbus_channel_offer_channel *)hdr;



	trace_vmbus_onoffer(offer);



	oldchannel = find_primary_channel_by_offer(offer);



	if (oldchannel != NULL) {

		atomic_dec(&vmbus_connection.offer_in_progress);



		/*

		 * We're resuming from hibernation: we expect the host to send

		 * exactly the same offers that we had before the hibernation.

		 */

		offer_sz = sizeof(*offer);

		if (memcmp(offer, &oldchannel->offermsg, offer_sz) == 0)

			return;



		pr_debug("Mismatched offer from the host (relid=%d)\n",

			 offer->child_relid);



		print_hex_dump_debug("Old vmbus offer: ", DUMP_PREFIX_OFFSET,

				     16, 4, &oldchannel->offermsg, offer_sz,

				     false);

		print_hex_dump_debug("New vmbus offer: ", DUMP_PREFIX_OFFSET,

				     16, 4, offer, offer_sz, false);

		return;

	}



	/* Allocate the channel object and save this offer. */

	newchannel = alloc_channel();

	if (!newchannel) {

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