gh: new action to run tests

We need to measure the impact of having only 2 CPUs and no KVM support.

Signed-off-by: Matthieu Baerts <matttbe@kernel.org>

.github/workflows/tests.yml

@@ -0,0 +1,93 @@
+name: "MPTCP Upstream Tests Validation"
+on:
+  push:
+    branches-ignore:
+      - 'archived/**'    # previous branches
+      - 't/**'           # TopGit tree
+      - 'net'            # part of the TopGit tree
+      - 'net-next'       # part of the TopGit tree
+      - 'for-review'     # part of the TopGit tree
+      - 'for-review-net' # part of the TopGit tree
+    tags:
+      - 'patchew/**'     # patchew is using tags
+      # ideally, we would take 'export/**' but the cache is per branch...
+      # In other words, when using tags, we can only use the cache if we re-tag.
+      # https://github.com/actions/cache/issues/556
+      # So we test the "export" branch and we try to find the tag later
+
+permissions: {}
+
+jobs:
+  tests:
+    name: "Tests (matrix)"
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        mode: ['normal', 'debug']
+        # TODO: selftest_mptcp_join: ['INPUT_RUN_TESTS_EXCEPT', 'INPUT_RUN_TESTS_ONLY']
+    permissions:
+      contents: read # to fetch code (actions/checkout)
+
+    steps:
+      - name: "Checkout"
+        uses: actions/checkout@v3
+
+      - name: "Find base branch"
+        id: branch
+        run: |
+          if [ "$(cat .git_markup)" = "MPTCP-related modifications only needed for our tests suite (mptcp-net)." ]; then
+            echo "name=export-net" >> ${GITHUB_OUTPUT}
+          else
+            echo "name=export" >> ${GITHUB_OUTPUT}
+          fi
+
+      - name: "Restore cache for CCache"
+        uses: actions/cache/restore@v3
+        id: restore-ccache
+        with:
+          path: ${{ github.workspace }}/.ccache
+          key: ${{ runner.os }}_tests_${{ steps.branch.outputs.name }}-${{ github.run_id }}-${{ github.run_attempt }}-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}_tests_${{ steps.branch.outputs.name }}-${{ github.run_id }}-${{ github.run_attempt }}-${{ github.sha }}
+            ${{ runner.os }}_tests_${{ steps.branch.outputs.name }}-${{ github.run_id }}-${{ github.run_attempt }}-
+            ${{ runner.os }}_tests_${{ steps.branch.outputs.name }}-${{ github.run_id }}-
+            ${{ runner.os }}_tests_${{ steps.branch.outputs.name }}-
+
+      - name: "Tests"
+        uses: multipath-tcp/mptcp-upstream-virtme-docker@latest
+        with:
+          ccache_maxsize: 600M ## 10/2^3/2=625: 10GB = project limit ; 2^3 = matrix ; 2: -net and net-next
+          mode: ${{ matrix.mode }}
+          # TODO: selftest_mptcp_join_only_except: ${{ matrix.selftest_mptcp_join }}
+
+      - name: "Artifacts (always)"
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: results
+          path: |
+            conclusion.txt
+            summary.txt
+            *.tap
+            config.zstd
+            *.tap.xml
+
+      - name: "Artifacts (failure)"
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: results
+          path: |
+            vmlinux.zstd
+            kmemleak.txt
+
+      - name: "Save cache for CCache"
+        if: github.ref == 'refs/heads/export' || github.ref == 'refs/heads/export-net'
+        uses: actions/cache/save@v3
+        with:
+          path: ${{ github.workspace }}/.ccache
+          key: ${{ steps.restore-ccache.outputs.cache-primary-key }}
+
+  # TODO: see build-validation.yml
+  # notif: