From 23a14e4f0ebc744ff39240561b2d7cc6a596af85 Mon Sep 17 00:00:00 2001
From: Isaac True <isaac.true@canonical.com>
Date: Wed, 12 Apr 2023 13:52:05 +0200
Subject: [PATCH] qemu: allow specifying the machine type

This allows QEMU machine types to be used other than the default "pc",
such as "q35". Valid alternative machine types can be identified with
the `qemu-system-x86_64 -M help` command.

Signed-off-by: Isaac True <isaac.true@canonical.com>
---
 spread/project.go   |  4 ++++
 spread/qemu.go      |  8 ++++++++
 spread/qemu_test.go | 33 +++++++++++++++++++++++++++++++++
 3 files changed, 45 insertions(+)

diff --git a/spread/project.go b/spread/project.go
index e70470f0..8ea19628 100644
--- a/spread/project.go
+++ b/spread/project.go
@@ -139,6 +139,10 @@ type System struct {
 
 	Priority OptionalInt
 	Manual   bool
+
+	// Type of machine emulated, only for qemu. Defaults to "pc", which is
+	// the QEMU default for x86_64
+	MachineType string `yaml:"machine-type"`
 }
 
 func (system *System) String() string { return system.Backend + ":" + system.Name }
diff --git a/spread/qemu.go b/spread/qemu.go
index 20f0bdb0..7dfed16a 100644
--- a/spread/qemu.go
+++ b/spread/qemu.go
@@ -121,6 +121,13 @@ func biosPath(biosName string) (string, error) {
 	return "", fmt.Errorf("cannot find bios path for %q", biosName)
 }
 
+func machineType(system *System) string {
+	if system.MachineType == "" {
+		return "pc"
+	}
+	return system.MachineType
+}
+
 func qemuCmd(system *System, path string, mem, port int) (*exec.Cmd, error) {
 	serial := fmt.Sprintf("telnet:127.0.0.1:%d,server,nowait", port+100)
 	monitor := fmt.Sprintf("telnet:127.0.0.1:%d,server,nowait", port+200)
@@ -133,6 +140,7 @@ func qemuCmd(system *System, path string, mem, port int) (*exec.Cmd, error) {
 		"-net", fwd,
 		"-serial", serial,
 		"-monitor", monitor,
+		"-M", machineType(system),
 		path)
 	if os.Getenv("SPREAD_QEMU_GUI") != "1" {
 		cmd.Args = append([]string{cmd.Args[0], "-nographic"}, cmd.Args[1:]...)
diff --git a/spread/qemu_test.go b/spread/qemu_test.go
index 619448ec..4e444611 100644
--- a/spread/qemu_test.go
+++ b/spread/qemu_test.go
@@ -1,6 +1,7 @@
 package spread_test
 
 import (
+	"fmt"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -91,3 +92,35 @@ func (s *qemuSuite) TestQemuCmdWithEfi(c *C) {
 		c.Check(strings.Contains(s, ":-bios:/usr/share/OVMF/OVMF_CODE.fd:"), Equals, tc.UseBiosQemuOption)
 	}
 }
+
+func (s *qemuSuite) TestQemuMachineTypes(c *C) {
+	imageName := "ubuntu-20.06-64"
+
+	restore := makeMockQemuImg(c, imageName)
+	defer restore()
+
+	tests := []struct {
+		MachineType         string
+		ExpectedMachineType string
+	}{
+		// Make sure the default is "pc"
+		{"", "pc"},
+		// Make sure the specified machine type is used
+		{"q35", "q35"},
+	}
+
+	for _, tc := range tests {
+		ms := &spread.System{
+			Name:        "some-name",
+			Image:       imageName,
+			Backend:     "qemu",
+			MachineType: tc.MachineType,
+		}
+		cmd, err := spread.QemuCmd(ms, "/path/to/image", 512, 9999)
+		c.Assert(err, IsNil)
+
+		s := strings.Join(cmd.Args, " ")
+		// Make sure the QEMU command specifies the given machine type, e.g. "-M pc"
+		c.Assert(s, Matches, fmt.Sprintf("^.*-M %s.*$", tc.ExpectedMachineType))
+	}
+}