RE: [virtio-comment] [PATCH 5/5] virtio-pci: implement VIRTIO_F_QUEUE_STATE

[Parav Pandit <parav@nvidia.com>]

> From: Zhu, Lingshan <lingshan.zhu@intel.com>
> Sent: Tuesday, September 12, 2023 6:39 PM
> 
> On 9/12/2023 6:41 PM, Parav Pandit wrote:
> >> From: Zhu, Lingshan <lingshan.zhu@intel.com>
> >> Sent: Tuesday, September 12, 2023 4:05 PM I mean, why do you think my
> >> series can not work with P2P
> > Because it misses the intermediate mode STOP that we have in series [1].
> >
> > [1]
> > https://lists.oasis-open.org/archives/virtio-comment/202309/msg00071.h
> > tml
> Again, when SUSPEND:
> 1) the device freezes, means stop operation in both data-path and control-path,
> except the device status
Exactly, including the RESET_VQ command also cannot be served because device is frozen.

> 2) a new feature bit will be introduced in V2, to allow RESET_VQ after SUSPEND
RESET_VQ after suspend is simply wrong. Because device is already suspended to not respond to some  extra RESET_VQ command.

> 3) if there is a device doing P2P against the device.
> They should be pass-through-ed to the same guest and should be suspended as
> well for LM, or it is a security problem.
There is no security problem. Multiple passthrough devices and P2P is already there in PCI using ACS for probably a decade now.