From: Dexuan Cui <de...@microsoft.com> 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 <de...@microsoft.com>
> ---
> drivers/hv/vmbus_drv.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
Reviewed-by: Michael Kelley <mikel...@microsoft.com>
>
> 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
