Re: [PATCH v4 1/3] virtio-gpu: validate host page alignment for MAP_FIXED blobs

[Lucas Amaral <lucaaamaral@gmail.com>]

On 2026-04-24, Alex Bennée wrote:
> Well we at least images for the Linux side which we can use. See
> tests/functional/aarch64/test_virt_gpu.py

Good pointer — that infrastructure should work. My local reproduction
is even simpler: a plain Ubuntu 24.04 ARM64 image, unmodified, with
stock Mesa. The failure surfaces immediately on:

  sudo vulkaninfo --summary
  sudo run_wayland timeout 120 vkmark

Without patch 1/3, virgl_renderer_resource_map_fixed() returns EINVAL
on the first 4KB-aligned blob and the guest renderer falls over.

> I wonder if TCG guests will also fail?

Yes — the MAP_FIXED requirement is a host kernel mmap() constraint,
not an accelerator one. The patch 1/3 guard sits in the
accelerator-agnostic path and protects all configurations, including
TCG.

> A lot of moving parts, do you have a rolled up branch I can test
> against?
> Any rolled up branch for this set as well?

Easier than a rolled-up branch — the three QEMU series apply cleanly
on current master in any order:

  Stack A (ISV=0 emulation):
    https://patchew.org/QEMU/20260409220614.65558-1-lucaaamaral@gmail.com/
  Stack B (this series):
    https://patchew.org/QEMU/20260424000544.9617-1-lucaaamaral@gmail.com/
  Stack C (Venus without OpenGL):
    https://patchew.org/QEMU/20260317182049.33848-1-lucaaamaral@gmail.com/

Renderer side just needs current virglrenderer main — the last macOS
Metal/Vulkan MR landed yesterday.

> This is a bit of a challenge - we will be loosing CirrusCI soon
> which has our only real MacOS build test. Either we get someone
> willing to host a custom runner or we need to find another CI
> runner that we can plug MacOS tests into.

Acknowledged — separate infrastructure problem, but I'm happy to
share my macOS test scripts/workflow if useful, and can ack-test
macOS-specific patches locally on Apple Silicon when asked.

Thanks,
Lucas