Re: [PATCH v2 1/2] drm/hyperv: validate resolution_count and harden VSP request paths

[Berkant Koc <me@berkoc.com>]

Hello Michael,

Thanks for the CoCo context, that lines up with what is in
vmbus_devs[] for the framebuffer device. The piecemeal approach is
what I am aiming for here.

v3 is on the list and addresses your three concrete points:

> This change should probably be a separate patch, as it's not really
> related to the bounds checking issue.
> [...]
> All that notwithstanding, I don't think your fix is needed in its
> current form.

Dropped from v3. You are right that the negotiate-version and
update-vram-location timeouts let hyperv_vmbus_probe() bail out and
free the device, so the stale-completion path is only reachable from
hyperv_vmbus_resume() after a get_supported_resolution() timeout.
That is a narrower fix and belongs in a separate patch against the
resume path, which I will send afterwards.

> Is there a separate problem here in that preferred_width and
> preferred_height are not set in the pre-WIN10 case?

Yes, separate problem, and I missed it in v2. The pre-WIN10 branch
in hyperv_connect_vsp() sets only screen_*_max and leaves preferred_*
at zero, which is inconsistent with the WIN10-failure path.

> Also, having to duplicate the fallback code is distasteful. Instead
> of having an "else" clause, maybe have a follow-up test for
> screen_width_max [...] being zero as an indicator [...]

Adopted in v3. The else branch is gone; the WIN10 path runs the probe
and the post-probe block applies the WIN8 defaults whenever
screen_width_max is still zero. One source of truth, both paths
converge on it.

> In my view, your commit message is a bit too detailed.

Rewritten in v3. The bounds check and the WIN8 fallback are now one
short paragraph each, focused on the "why".

Series: <cover.1779221339.git.me@berkoc.com>

The v3 patches carry an `Assisted-by: Claude:claude-opus-4-7
berkoc-pipeline` trailer per the kernel coding-assistants policy.
Code, analysis and review responses are mine; the model is used as
a structured reviewer under human verification.

Thanks,
Berkant