Add kselftest comparison

Signed-off-by: Shreeya Patel <spatel@ciq.com>

Author: shreeya-patel98

.github/workflows/kernel-build-and-test-x86_64.yml

@@ -189,3 +189,42 @@ jobs:
           output/kselftests-*.log
           output/dmesg-*.log
         retention-days: 7
+
+  compare-results:
+    name: Compare with previous run
+    runs-on: kernel-build
+    needs: test-kselftest
+    if: success() || failure()
+
+    steps:
+    - name: Download current kselftest logs
+      uses: actions/download-artifact@v4
+      with:
+        name: kselftest-logs-x86_64
+        path: output-current
+
+    - name: Download previous kselftest logs
+      uses: dawidd6/action-download-artifact@v3
+      with:
+        workflow: kernel-build-and-test-x86_64.yml
+        name: kselftest-logs-x86_64
+        path: output-previous
+        branch: ${{ github.ref_name }}
+        search_artifacts: true
+        skip_unpack: false
+        if_no_artifact_found: warn
+      continue-on-error: true
+
+    - name: Compare test results
+      run: |
+        if [ -f output-previous/kselftests-*.log ]; then
+          BEFORE=$(grep -a '^ok' output-previous/kselftests-*.log | wc -l)
+          AFTER=$(grep -a '^ok' output-current/kselftests-*.log | wc -l)
+          echo "Previous run: $BEFORE passing tests"
+          echo "Current run: $AFTER passing tests"
+          if [ "$AFTER" -lt "$BEFORE" ]; then
+            echo "::warning::Regression detected: $BEFORE -> $AFTER"
+          fi
+        else
+          echo "No previous results found, skipping comparison"
+        fi