qemu: tcg: use max by default

The previous default value `qemu64` for Intel on ARM was unable to boot
recent guests as it only supports x86_64 v1 instructions.

CentOS Stream 10 is known to need x86_64 v3 or later.

Fix issue 3063

Signed-off-by: Akihiro Suda <[email protected]>

Author: AkihiroSuda

pkg/limayaml/defaults.go

@@ -62,33 +62,30 @@ var (
 
 func defaultCPUType() CPUType {
 	cpuType := map[Arch]string{
-		AARCH64: "cortex-a76", // available since QEMU 7.1 (Aug 2022)
-		ARMV7L:  "cortex-a7",
-		// Since https://github.com/lima-vm/lima/pull/494, we use qemu64 cpu for better emulation of x86_64.
-		X8664:   "qemu64",
+		AARCH64: "max",
+		ARMV7L:  "max",
+		// x86_64 + TCG + max was previously unstable until 2021.
+		// https://bugzilla.redhat.com/show_bug.cgi?id=1999700
+		// https://bugs.launchpad.net/qemu/+bug/1748296
+		X8664:   "max",
 		RISCV64: "max",
-		S390X:   "qemu", // FIXME: what is the right choice for s390x?
+		S390X:   "max",
 	}
 	for arch := range cpuType {
 		if IsNativeArch(arch) && IsAccelOS() {
 			if HasHostCPU() {
 				cpuType[arch] = "host"
-			} else if HasMaxCPU() {
-				cpuType[arch] = "max"
 			}
 		}
 		if arch == X8664 && runtime.GOOS == "darwin" {
-			switch cpuType[arch] {
-			case "host", "max":
-				// disable AVX-512, since it requires trapping instruction faults in guest
-				// Enterprise Linux requires either v2 (SSE4) or v3 (AVX2), but not yet v4.
-				cpuType[arch] += ",-avx512vl"
-
-				// Disable pdpe1gb on Intel Mac
-				// https://github.com/lima-vm/lima/issues/1485
-				// https://stackoverflow.com/a/72863744/5167443
-				cpuType[arch] += ",-pdpe1gb"
-			}
+			// disable AVX-512, since it requires trapping instruction faults in guest
+			// Enterprise Linux requires either v2 (SSE4) or v3 (AVX2), but not yet v4.
+			cpuType[arch] += ",-avx512vl"
+
+			// Disable pdpe1gb on Intel Mac
+			// https://github.com/lima-vm/lima/issues/1485
+			// https://stackoverflow.com/a/72863744/5167443
+			cpuType[arch] += ",-pdpe1gb"
 		}
 	}
 	return cpuType
@@ -1273,11 +1270,6 @@ func HasHostCPU() bool {
 	return false
 }
 
-func HasMaxCPU() bool {
-	// windows: WHPX: Unexpected VP exit code 4
-	return HasHostCPU()
-}
-
 func IsNativeArch(arch Arch) bool {
 	nativeX8664 := arch == X8664 && runtime.GOARCH == "amd64"
 	nativeAARCH64 := arch == AARCH64 && runtime.GOARCH == "arm64"

pkg/qemu/qemu.go

@@ -548,7 +548,7 @@ func Cmdline(ctx context.Context, cfg Config) (exe string, args []string, err er
 	// Machine
 	switch *y.Arch {
 	case limayaml.X8664:
-		if strings.HasPrefix(cpu, "qemu64") && runtime.GOOS != "windows" {
+		if accel == "tcg" && runtime.GOOS != "windows" { // FIXME: Any reason to exclude windows here?
 			// use q35 machine with vmware io port disabled.
 			args = appendArgsIfNoConflict(args, "-machine", "q35,vmport=off")
 			// use tcg accelerator with multi threading with 512MB translation block size

templates/_images/centos-stream-10.yaml

@@ -31,9 +31,3 @@ firmware:
   # CentOS Stream 10 still requires legacyBIOS
   # https://issues.redhat.com/browse/CS-2672
   legacyBIOS: true
-
-cpuType:
-  # When emulating Intel on ARM hosts, Lima uses the "qemu64" CPU by default (https://github.com/lima-vm/lima/pull/494).
-  # However, CentOS Stream 10 kernel reboots indefinitely due to lack of the support for x86_64-v3 instructions.
-  # This issue is tracked in <https://github.com/lima-vm/lima/issues/3063>.
-  x86_64: "Haswell-v4"

templates/default.yaml

@@ -334,10 +334,10 @@ os: null
 # Setting of instructions is supported like this: "qemu64,+ssse3".
 # 🟢 Builtin default: hard-coded arch map with type (see the output of `limactl info | jq .defaultTemplate.cpuType`)
 cpuType:
-#   aarch64: "cortex-a76" # (or "host" when running on aarch64 host)
-#   armv7l: "cortex-a7" # (or "host" when running on armv7l host)
-#   riscv64: "rv64" # (or "host" when running on riscv64 host)
-#   x86_64: "qemu64" # (or "host,-pdpe1gb" when running on x86_64 host)
+#   aarch64: "max" # (or "host" when running on aarch64 host)
+#   armv7l:  "max" # (or "host" when running on armv7l host)
+#   riscv64: "max" # (or "host" when running on riscv64 host)
+#   x86_64:  "max" # (or "host,-pdpe1gb" when running on x86_64 host)
 
 rosetta:
   # Enable Rosetta inside the VM; needs `vmType: vz`