Re: [PATCH v3] Drivers: hv: vmbus: Add /sys/bus/vmbus/hibernation

[Wei Liu]

On Thu, Jan 07, 2021 at 06:08:51PM +0000, Michael Kelley wrote:
> From: Dexuan Cui <decui@xxxxxxxxxxxxx> Sent: Wednesday, January 6, 2021 5:46 PM
> > 
> > When a Linux VM runs on Hyper-V, if the host toolstack doesn't support
> > hibernation for the VM (this happens on old Hyper-V hosts like Windows
> > Server 2016, or new Hyper-V hosts if the admin or user doesn't declare
> > the hibernation intent for the VM), the VM is discouraged from trying
> > hibernation (because the host doesn't guarantee that the VM's virtual
> > hardware configuration will remain exactly the same across hibernation),
> > i.e. the VM should not try to set up the swap partition/file for
> > hibernation, etc.
> > 
> > x86 Hyper-V uses the presence of the virtual ACPI S4 state as the
> > indication of the host toolstack support for a VM. Currently there is
> > no easy and reliable way for the userspace to detect the presence of
> > the state (see https://lkml.org/lkml/2020/12/11/1097).  Add
> > /sys/bus/vmbus/hibernation for this purpose.
> > 
> > Signed-off-by: Dexuan Cui <decui@xxxxxxxxxxxxx>
[...]
> 
> Reviewed-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>

Queued for hyperv-next. Thanks.

Wei.

>