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

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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: Dexuan Cui <decui@microsoft.com>
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Dexuan Cui 2019-09-05 23:01:18 +00:00 committed by Sasha Levin
parent 271b2224d4
commit e3ede02add
1 changed files with 57 additions and 1 deletions
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58
drivers/hv/channel_mgmt.c
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@ -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) {