CI: Add emulated non-AVX2 x86_64 functional tests

Add a build_kat matrix row that builds the x86_64 C backend without
AVX2 (--no-auto, so the native backend self-disables) and runs it under
an emulated non-AVX2 CPU (qemu -cpu Snowridge), covering both opt and
no_opt. This keeps the portable build runnable on pre-AVX2 x86_64.

To wire this in cleanly, exec_wrapper is now plain matrix data instead
of being computed from vlen: the riscv rows carry their exec_wrapper
explicitly, and per-row build flags travel via a new extra_args field.

Jobs are now identified by the matrix 'name' field, with the target
descriptor baked into each name.

Drop the "external" exclusion since none of the jobs is hosted
on the pqcp runners anymore.

Signed-off-by: Matthias J. Kannwischer <matthias@zerorisc.com>

Author: mkannwischer

.github/workflows/ci.yml

@@ -13,136 +13,88 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        external:
-         - ${{ github.repository_owner != 'pq-code-package' }}
         target:
          - runner: macos-latest
-           name: 'MacOS (aarch64)'
+           name: 'macOS (aarch64)'
            arch: mac
            mode: native
            nix_shell: ci
          - runner: macos-15-intel
-           name: 'MacOS (x86_64)'
+           name: 'macOS (x86_64)'
            arch: mac
            mode: native
            nix_shell: ci
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'aarch64'
            arch: aarch64
            mode: native
            nix_shell: ci
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'x86_64, cross'
            arch: x86_64
            mode: cross-x86_64
            nix_shell: cross-x86_64
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'x86_64, cross, no AVX2'
+           arch: x86_64
+           mode: cross-x86_64
+           nix_shell: cross-x86_64
+           exec_wrapper: 'qemu-x86_64 -cpu Snowridge'
+           extra_args: '--no-auto'
+         - runner: ubuntu-24.04-arm
+           name: 'riscv64, cross, VLEN=128'
            arch: riscv64
            mode: cross-riscv64
            nix_shell: cross-riscv64
            vlen: 128
+           exec_wrapper: 'qemu-riscv64 -cpu rv64,v=true,vlen=128'
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'riscv64, cross, VLEN=256'
            arch: riscv64
            mode: cross-riscv64
            nix_shell: cross-riscv64
            vlen: 256
+           exec_wrapper: 'qemu-riscv64 -cpu rv64,v=true,vlen=256'
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'riscv64, cross, VLEN=512'
            arch: riscv64
            mode: cross-riscv64
            nix_shell: cross-riscv64
            vlen: 512
+           exec_wrapper: 'qemu-riscv64 -cpu rv64,v=true,vlen=512'
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'riscv64, cross, VLEN=1024'
            arch: riscv64
            mode: cross-riscv64
            nix_shell: cross-riscv64
            vlen: 1024
+           exec_wrapper: 'qemu-riscv64 -cpu rv64,v=true,vlen=1024'
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (aarch64)'
+           name: 'riscv32, cross'
            arch: riscv32
            mode: cross-riscv32
            nix_shell: cross-riscv32
          - runner: ubuntu-24.04-arm
-           name: 'ubuntu-latest (ppc64le)'
+           name: 'ppc64le, cross'
            arch: ppc64le
            mode: cross-ppc64le
            nix_shell: cross-ppc64le
          - runner: ubuntu-latest
-           name: 'ubuntu-latest (x86_64)'
+           name: 'x86_64'
            arch: x86_64
            mode: native
            nix_shell: ci
          - runner: ubuntu-latest
-           name: 'ubuntu-latest (x86_64)'
+           name: 'aarch64, cross'
            arch: aarch64
            mode: cross-aarch64
            nix_shell: cross-aarch64
          - runner: ubuntu-latest
-           name: 'ubuntu-latest (x86_64)'
+           name: 'aarch64_be, cross'
            arch: aarch64_be
            mode: cross-aarch64_be
            nix_shell: cross-aarch64_be
-        exclude:
-          - {external: true,
-             target: {
-               runner: ubuntu-24.04-arm,
-               name: 'ubuntu-latest (aarch64)',
-               arch: aarch64,
-               mode: native,
-               nix_shell: ci
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-24.04-arm,
-               name: 'ubuntu-latest (aarch64)',
-               arch: x86_64,
-               mode: cross-x86_64,
-               nix_shell: cross-x86_64
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-24.04-arm,
-               name: 'ubuntu-latest (aarch64)',
-               arch: riscv32,
-               mode: cross-riscv32,
-               nix_shell: cross-riscv32
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-24.04-arm,
-               name: 'ubuntu-latest (ppc64le)',
-               arch: ppc64le,
-               mode: cross-ppc64le,
-               nix_shell: cross-ppc64le
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-latest,
-               name: 'ubuntu-latest (x86_64)',
-               arch: x86_64,
-               mode: native,
-               nix_shell: ci
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-latest,
-               name: 'ubuntu-latest (x86_64)',
-               arch: aarch64,
-               mode: cross-aarch64,
-               nix_shell: cross-aarch64
-             }}
-          - {external: true,
-             target: {
-               runner: ubuntu-latest,
-               name: 'ubuntu-latest (x86_64)',
-               arch: aarch64_be,
-               mode: cross-aarch64_be,
-               nix_shell: cross-aarch64_be
-             }}
-    name: Functional tests (${{ matrix.target.arch }}${{ matrix.target.mode != 'native' && ', cross' || ''}}${{ matrix.target.vlen && format(', VLEN={0}', matrix.target.vlen) || '' }})
+    name: Functional tests (${{ matrix.target.name }})
     runs-on: ${{ matrix.target.runner }}
     steps:
       - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
@@ -155,7 +107,8 @@ jobs:
           nix-cache: ${{ matrix.target.mode == 'native' && 'false' || 'true' }}
           gh_token: ${{ secrets.GITHUB_TOKEN }}
           compile_mode: ${{ matrix.target.mode }}
-          exec_wrapper: ${{ matrix.target.vlen && format('qemu-riscv64 -cpu rv64,v=true,vlen={0}', matrix.target.vlen) || '' }}
+          extra_args: ${{ matrix.target.extra_args || '' }}
+          exec_wrapper: ${{ matrix.target.exec_wrapper || '' }}
           opt: 'no_opt'
       - name: build + test (+debug+memsan+ubsan, native)
         uses: ./.github/actions/multi-functest
@@ -175,7 +128,8 @@ jobs:
           nix-cache: ${{ matrix.target.mode == 'native' && 'false' || 'true' }}
           gh_token: ${{ secrets.GITHUB_TOKEN }}
           compile_mode: ${{ matrix.target.mode }}
-          exec_wrapper: ${{ matrix.target.vlen && format('qemu-riscv64 -cpu rv64,v=true,vlen={0}', matrix.target.vlen) || '' }}
+          extra_args: ${{ matrix.target.extra_args || '' }}
+          exec_wrapper: ${{ matrix.target.exec_wrapper || '' }}
           opt: 'opt'
       - name: build + test (cross, opt, +debug)
         uses: ./.github/actions/multi-functest
@@ -186,7 +140,8 @@ jobs:
           nix-cache: ${{ matrix.target.mode == 'native' && 'false' || 'true' }}
           gh_token: ${{ secrets.GITHUB_TOKEN }}
           compile_mode: ${{ matrix.target.mode }}
-          exec_wrapper: ${{ matrix.target.vlen && format('qemu-riscv64 -cpu rv64,v=true,vlen={0}', matrix.target.vlen) || '' }}
+          extra_args: ${{ matrix.target.extra_args || '' }}
+          exec_wrapper: ${{ matrix.target.exec_wrapper || '' }}
           cflags: "-DMLKEM_DEBUG"
           opt: 'opt'
       - name: build + test (cross, opt, C90)
@@ -197,7 +152,8 @@ jobs:
           nix-cache: 'true'
           gh_token: ${{ secrets.GITHUB_TOKEN }}
           compile_mode: ${{ matrix.target.mode }}
-          exec_wrapper: ${{ matrix.target.vlen && format('qemu-riscv64 -cpu rv64,v=true,vlen={0}', matrix.target.vlen) || '' }}
+          extra_args: ${{ matrix.target.extra_args || '' }}
+          exec_wrapper: ${{ matrix.target.exec_wrapper || '' }}
           cflags: "-std=c90"
           opt: 'opt'
   ppc64le_tests: