From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Friday, September 4, 2020 7:56 PM > > After we Stop and later Start a VM that uses Accelerated Networking (NIC > SR-IOV), currently the VF vmbus device's Instance GUID can change, so after > vmbus_bus_resume() -> vmbus_request_offers(), vmbus_onoffer() can not find > the original vmbus channel of the VF, and hence we can't complete() > vmbus_connection.ready_for_resume_event in check_ready_for_resume_event(), > and the VM hangs in vmbus_bus_resume() forever. > > Fix the issue by adding a timeout, so the resuming can still succeed, and > the saved state is not lost, and according to my test, the user can disable > Accelerated Networking and then will be able to SSH into the VM for > further recovery. Also prevent the VM in question from suspending again. > > The host will be fixed so in future the Instance GUID will stay the same > across hibernation. > > Fixes: d8bd2d442bb2 ("Drivers: hv: vmbus: Resume after fixing up old primary channels") > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx> > --- > drivers/hv/vmbus_drv.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx> > > diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c > index 910b6e90866c..946d0aba101f 100644 > --- a/drivers/hv/vmbus_drv.c > +++ b/drivers/hv/vmbus_drv.c > @@ -2382,7 +2382,10 @@ static int vmbus_bus_suspend(struct device *dev) > if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0) > wait_for_completion(&vmbus_connection.ready_for_suspend_event); > > - WARN_ON(atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0); > + if (atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0) { > + pr_err("Can not suspend due to a previous failed resuming\n"); > + return -EBUSY; > + } > > mutex_lock(&vmbus_connection.channel_mutex); > > @@ -2456,7 +2459,9 @@ static int vmbus_bus_resume(struct device *dev) > > vmbus_request_offers(); > > - wait_for_completion(&vmbus_connection.ready_for_resume_event); > + if (wait_for_completion_timeout( > + &vmbus_connection.ready_for_resume_event, 10 * HZ) == 0) > + pr_err("Some vmbus device is missing after suspending?\n"); > > /* Reset the event for the next suspend. */ > reinit_completion(&vmbus_connection.ready_for_suspend_event); > -- > 2.19.1