Re: [PATCH v2] drivers/virt: vmgenid: add vm generation id driver

[Jann Horn <jannh@google.com>]

[resend in the hope that amazon will accept my mail this time instead
of replying "550 Too many invalid recipients" again]

On Fri, Nov 20, 2020 at 11:29 PM Jann Horn <jannh@google.com> wrote:
> On Mon, Nov 16, 2020 at 4:35 PM Catangiu, Adrian Costin
> <acatan@amazon.com> wrote:
> > This patch is a driver that exposes a monotonic incremental Virtual
> > Machine Generation u32 counter via a char-dev FS interface that
> > provides sync and async VmGen counter updates notifications. It also
> > provides VmGen counter retrieval and confirmation mechanisms.
> >
> > The hw provided UUID is not exposed to userspace, it is internally
> > used by the driver to keep accounting for the exposed VmGen counter.
> > The counter starts from zero when the driver is initialized and
> > monotonically increments every time the hw UUID changes (the VM
> > generation changes).
> >
> > On each hw UUID change, the new hypervisor-provided UUID is also fed
> > to the kernel RNG.
>
> As for v1:
>
> Is there a reasonable usecase for the "confirmation" mechanism? It
> doesn't seem very useful to me.
>
> How do you envision integrating this with libraries that have to work
> in restrictive seccomp sandboxes? If this was in the vDSO, that would
> be much easier.