Re: [PATCH RFC v2] vfio: Documentation for the migration region

[Jason Gunthorpe <jgg@nvidia.com>]

On Wed, Dec 01, 2021 at 09:54:27AM +0000, Shameerali Kolothum Thodi wrote:

> So just to make it clear , if a device declares that it doesn't support NDMA
> and P2P, is the v1 version of the spec good enough or we still need to take
> care the case that a malicious user might try MMIO access in !RUNNING
> state and should have kernel infrastructure in place to safe guard that?

My thinking is so long as the hostile user space cannot compromise the
kernel it is OK. A corrupted migration is acceptable if userspace is
not following the rules.

From a qemu perspective it should prevent a hostile VM from corrupting
the migration, as that is allowing the VM to attack the infrastructure
even if it hopefully only harms itself.

> (Just a note to clarify that these are not HNS devices per se. HNS actually
> stands for HiSilicon Network Subsystem and doesn't currently have live
> migration capability. The devices capable of live migration are HiSilicon
> Accelerator devices).

Sorry, I mostly talk to the hns team ;)

Jason