From d0527a928aa32ad9f34d3f6ba223aa72845e644f Mon Sep 17 00:00:00 2001
From: Daniel Rossbach <daniel@family-neuner.de>
Date: Fri, 10 Jun 2022 16:03:51 +0200
Subject: [PATCH] qemu driver: Add option to configure drive_interface (#11864)

---
 .changelog/11864.txt                  |  3 +++
 drivers/qemu/driver.go                | 25 ++++++++++++++++++++++++-
 drivers/qemu/driver_test.go           | 21 ++++++++++++++++++---
 website/content/docs/drivers/qemu.mdx |  4 ++++
 4 files changed, 49 insertions(+), 4 deletions(-)
 create mode 100644 .changelog/11864.txt

diff --git a/.changelog/11864.txt b/.changelog/11864.txt
new file mode 100644
index 000000000000..9ca1db038bda
--- /dev/null
+++ b/.changelog/11864.txt
@@ -0,0 +1,3 @@
+```release-note:improvement
+qemu: Added option to configure `drive_interface`
+```
diff --git a/drivers/qemu/driver.go b/drivers/qemu/driver.go
index aaa8d03018cc..23c127ee5457 100644
--- a/drivers/qemu/driver.go
+++ b/drivers/qemu/driver.go
@@ -95,6 +95,7 @@ var (
 	// a taskConfig within a job. It is returned in the TaskConfigSchema RPC
 	taskConfigSpec = hclspec.NewObject(map[string]*hclspec.Spec{
 		"image_path":        hclspec.NewAttr("image_path", "string", true),
+		"drive_interface":   hclspec.NewAttr("drive_interface", "string", false),
 		"accelerator":       hclspec.NewAttr("accelerator", "string", false),
 		"graceful_shutdown": hclspec.NewAttr("graceful_shutdown", "bool", false),
 		"guest_agent":       hclspec.NewAttr("guest_agent", "bool", false),
@@ -125,6 +126,7 @@ type TaskConfig struct {
 	Args             []string           `codec:"args"`     // extra arguments to qemu executable
 	PortMap          hclutils.MapStrInt `codec:"port_map"` // A map of host port and the port name defined in the image manifest file
 	GracefulShutdown bool               `codec:"graceful_shutdown"`
+	DriveInterface   string             `codec:"drive_interface"` // Use interface for image
 	GuestAgent       bool               `codec:"guest_agent"`
 }
 
@@ -344,6 +346,19 @@ func isAllowedImagePath(allowedPaths []string, allocDir, imagePath string) bool
 	return false
 }
 
+// hardcoded list of drive interfaces, Qemu currently supports
+var allowedDriveInterfaces = []string{"ide", "scsi", "sd", "mtd", "floppy", "pflash", "virtio", "none"}
+
+func isAllowedDriveInterface(driveInterface string) bool {
+	for _, ai := range allowedDriveInterfaces {
+		if driveInterface == ai {
+			return true
+		}
+	}
+
+	return false
+}
+
 // validateArgs ensures that all QEMU command line params are in the
 // allowlist. This function must be called after all interpolation has
 // taken place.
@@ -414,12 +429,20 @@ func (d *Driver) StartTask(cfg *drivers.TaskConfig) (*drivers.TaskHandle, *drive
 		return nil, nil, err
 	}
 
+	driveInterface := "ide"
+	if driverConfig.DriveInterface != "" {
+		driveInterface = driverConfig.DriveInterface
+	}
+	if !isAllowedDriveInterface(driveInterface) {
+		return nil, nil, fmt.Errorf("Unsupported drive_interface")
+	}
+
 	args := []string{
 		absPath,
 		"-machine", "type=pc,accel=" + accelerator,
 		"-name", vmID,
 		"-m", mem,
-		"-drive", "file=" + vmPath,
+		"-drive", "file=" + vmPath + ",if=" + driveInterface,
 		"-nographic",
 	}
 
diff --git a/drivers/qemu/driver_test.go b/drivers/qemu/driver_test.go
index 5d2b71538e91..7bb27d1a7885 100644
--- a/drivers/qemu/driver_test.go
+++ b/drivers/qemu/driver_test.go
@@ -390,6 +390,7 @@ func TestConfig_ParseAllHCL(t *testing.T) {
 	cfgStr := `
 config {
   image_path = "/tmp/image_path"
+  drive_interface = "virtio"
   accelerator = "kvm"
   args = ["arg1", "arg2"]
   port_map {
@@ -400,9 +401,10 @@ config {
 }`
 
 	expected := &TaskConfig{
-		ImagePath:   "/tmp/image_path",
-		Accelerator: "kvm",
-		Args:        []string{"arg1", "arg2"},
+		ImagePath:      "/tmp/image_path",
+		DriveInterface: "virtio",
+		Accelerator:    "kvm",
+		Args:           []string{"arg1", "arg2"},
 		PortMap: map[string]int{
 			"http":  80,
 			"https": 443,
@@ -416,6 +418,19 @@ config {
 	require.EqualValues(t, expected, tc)
 }
 
+func TestIsAllowedDriveInterface(t *testing.T) {
+	validInterfaces := []string{"ide", "scsi", "sd", "mtd", "floppy", "pflash", "virtio", "none"}
+	invalidInterfaces := []string{"foo", "virtio-foo"}
+
+	for _, i := range validInterfaces {
+		require.Truef(t, isAllowedDriveInterface(i), "drive_interface should be allowed: %v", i)
+	}
+
+	for _, i := range invalidInterfaces {
+		require.Falsef(t, isAllowedDriveInterface(i), "drive_interface should be not allowed: %v", i)
+	}
+}
+
 func TestIsAllowedImagePath(t *testing.T) {
 	ci.Parallel(t)
 
diff --git a/website/content/docs/drivers/qemu.mdx b/website/content/docs/drivers/qemu.mdx
index 30cb1bf0ee98..a5e874ceea92 100644
--- a/website/content/docs/drivers/qemu.mdx
+++ b/website/content/docs/drivers/qemu.mdx
@@ -42,6 +42,10 @@ The `qemu` driver supports the following configuration in the job spec:
   contains the image in a subfolder, the path will need to be the relative path
   (`subdir/from_archive/my.img`).
 
+- `drive_interface` - (Optional) This option defines on which type of interface
+  the drive is connected. Available types are: `ide`, `scsi`, `sd`, `mtd`,
+  `floppy`, `pflash`, `virtio` and `none`. Default is `ide`.
+
 - `accelerator` - (Optional) The type of accelerator to use in the invocation.
   If the host machine has `qemu` installed with KVM support, users can specify
   `kvm` for the `accelerator`. Default is `tcg`.