Add support for lscpu_check TuneD built-in

This change adds support for lscpu_check TuneD built-in.

Other changes
  * Drop the severity from ERROR to WARNING in execTuneDBuiltin()
  * Be more specific what is the impact of calling unsupported TuneD
    built-in function

Resolves: OCPBUGS-66214

Author: jmencak

pkg/tuned/tuned_parser.go

@@ -6,6 +6,7 @@ import (
 	"io"      // io.EOF
 	"os"      // os.Stat()
 	"os/exec" // os.Exec()
+	"regexp"  // regexp.Compile()
 	"strings" // strings.Split()
 	"syscall" // syscall.SIGHUP, ...
 	"time"    // time.Second, ...
@@ -309,6 +310,49 @@ func execCmd(command []string) (string, error) {
 	return out, nil
 }
 
+// lscpu_check checks `lscpuStr` (lscpu output) against regular expressions.
+// Accepts args in the form: REGEX1, STR1, REGEX2, STR2, ...[, STR_FALLBACK]
+// If REGEX1 matches something in the output it returns STR1,
+// if REGEX2 matches it returns STR2, etc.
+// It stops on the first match. If no regex matches, it returns STR_FALLBACK
+// (or empty string if no fallback is provided).
+func lscpu_check(lscpuStr string, args []string) (string, error) {
+	var fallback string
+
+	if len(args) < 2 {
+		return "", fmt.Errorf("lscpu_check requires at least 2 arguments, got %d", len(args))
+	}
+
+	// See if we have a fallback (odd number of args).
+	if len(args)%2 == 1 {
+		fallback = args[len(args)-1]
+		args = args[:len(args)-1]
+	}
+
+	for i := 0; i < len(args); i += 2 {
+		regexStr := args[i]
+		resultStr := args[i+1]
+
+		// Enable multi-line matching: (?m) makes ^ and $ match line boundaries.
+		// Only add (?m) if not already present.
+		if len(regexStr) < 4 || regexStr[:4] != "(?m)" {
+			regexStr = "(?m)" + regexStr
+		}
+
+		re, err := regexp.Compile(regexStr)
+		if err != nil {
+			return "", fmt.Errorf("invalid regex '%s': %w", regexStr, err)
+		}
+
+		if re.MatchString(lscpuStr) {
+			return resultStr, nil
+		}
+	}
+
+	// No match found, return fallback.
+	return fallback, nil
+}
+
 // execTuneDBuiltin executes TuneD built-in function 'function' with
 // arguments 'args'.  Returns the result/expansion of running the built-in.
 // If the execution of the built-in fails, returns the string 'onFail'.
@@ -317,7 +361,7 @@ func execTuneDBuiltin(function string, args []string, onFail string) string {
 	case "exec":
 		out, err := execCmd(args)
 		if err != nil {
-			klog.Errorf("error calling built-in exec: %v", err)
+			klog.Warningf("failure calling built-in exec: %v", err)
 			return onFail
 		}
 		return out
@@ -330,21 +374,35 @@ func execTuneDBuiltin(function string, args []string, onFail string) string {
 		// argument 2.  Note the expansion to argument 2 is done also on error
 		// to match the semantics of the TuneD "virt_check".
 		if len(args) != 2 {
-			klog.Errorf("built-in \"virt_check\" requires 2 arguments")
+			klog.Warningf("built-in \"virt_check\" requires 2 arguments")
 			return onFail
 		}
 		out, err := execCmd([]string{"virt-what"})
 		if err == nil && len(out) > 0 {
 			return args[0]
 		}
 		if err != nil {
-			klog.Errorf("failure calling built-in exec: %v", err)
+			klog.Warningf("failure calling built-in exec: %v", err)
 		}
 
 		return args[1]
 
+	case "lscpu_check":
+		lscpuOut, err := execCmd([]string{"lscpu"})
+		if err != nil {
+			klog.Warningf("failure calling built-in lscpu_check: %v", err)
+			return onFail
+		}
+		out, err := lscpu_check(lscpuOut, args)
+		if err != nil {
+			klog.Warningf("failure calling built-in lscpu_check: %v", err)
+			return onFail
+		}
+
+		return out
+
 	default:
-		klog.Errorf("calling unsupported built-in: %v", function)
+		klog.Warningf("calling unsupported built-in: %q, TuneD reloads on config changes may not work properly", function)
 		// unsupported built-in
 	}
 

pkg/tuned/tuned_parser_test.go

@@ -67,3 +67,116 @@ func TestBuiltinExpansion(t *testing.T) {
 		}
 	}
 }
+
+func TestLscpuCheckARM(t *testing.T) {
+	lscpuARM := `Architecture:                         aarch64
+CPU op-mode(s):                       32-bit, 64-bit
+Byte Order:                           Little Endian
+CPU(s):                               80
+On-line CPU(s) list:                  0-79
+Vendor ID:                            ARM
+BIOS Vendor ID:                       Ampere(R)
+Model name:                           Neoverse-N1
+BIOS Model name:                      Ampere(R) Altra(R) Processor Q80-30 CPU @ 3.0GHz
+BIOS CPU family:                      257
+Model:                                1
+Thread(s) per core:                   1
+Core(s) per socket:                   80
+Socket(s):                            1
+Stepping:                             r3p1
+Frequency boost:                      disabled
+CPU(s) scaling MHz:                   100%
+CPU max MHz:                          3000.0000
+CPU min MHz:                          1000.0000
+BogoMIPS:                             50.00
+Flags:                                fp asimd evtstrm aes pmull sha1 sha2 crc32 atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp
+L1d cache:                            5 MiB (80 instances)
+L1i cache:                            5 MiB (80 instances)
+L2 cache:                             80 MiB (80 instances)
+NUMA node(s):                         1
+NUMA node0 CPU(s):                    0-79
+Vulnerability Gather data sampling:   Not affected
+Vulnerability Itlb multihit:          Not affected
+Vulnerability L1tf:                   Not affected
+Vulnerability Mds:                    Not affected
+Vulnerability Meltdown:               Not affected
+Vulnerability Mmio stale data:        Not affected
+Vulnerability Reg file data sampling: Not affected
+Vulnerability Retbleed:               Not affected
+Vulnerability Spec rstack overflow:   Not affected
+Vulnerability Spec store bypass:      Mitigation; Speculative Store Bypass disabled via prctl
+Vulnerability Spectre v1:             Mitigation; __user pointer sanitization
+Vulnerability Spectre v2:             Mitigation; CSV2, BHB
+Vulnerability Srbds:                  Not affected
+Vulnerability Tsx async abort:        Not affected
+`
+
+	tests := []struct {
+		name    string
+		args    []string
+		want    string
+		wantErr bool
+	}{
+		{
+			name:    "Match ARM Vendor ID",
+			args:    []string{"Vendor ID\\:\\s*GenuineIntel", "intel", "Vendor ID\\:\\s*AuthenticAMD", "amd", "Architecture\\:\\s*aarch64", "arm", "unknown"},
+			want:    "arm",
+			wantErr: false,
+		},
+		{
+			name:    "Match aarch64 architecture",
+			args:    []string{"Architecture\\:\\s*x86_64", "x86", "Architecture\\:\\s*aarch64", "aarch64"},
+			want:    "aarch64",
+			wantErr: false,
+		},
+		{
+			name:    "No match returns fallback",
+			args:    []string{"NonExistentPattern", "result", "fallback"},
+			want:    "fallback",
+			wantErr: false,
+		},
+		{
+			name:    "No match no fallback returns empty string",
+			args:    []string{"AuthenticAMD", "amd"},
+			want:    "",
+			wantErr: false,
+		},
+		{
+			name:    "First match wins",
+			args:    []string{"^Architecture", "aarch64", "ARM", "arm", "unknown"},
+			want:    "aarch64",
+			wantErr: false,
+		},
+		{
+			name:    "One argument returns error",
+			args:    []string{"fallback"},
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "Zero arguments returns error",
+			args:    []string{},
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "Invalid regex returns error",
+			args:    []string{"[invalid(regex", "result"},
+			want:    "",
+			wantErr: true,
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := lscpu_check(lscpuARM, tc.args)
+			if (err != nil) != tc.wantErr {
+				t.Errorf("lscpu_check() error = %v, wantErr %v", err, tc.wantErr)
+				return
+			}
+			if got != tc.want {
+				t.Errorf("lscpu_check() = %v, want %v", got, tc.want)
+			}
+		})
+	}
+}