gpu: mount by-path directory

cmd/gpu_plugin/gpu_plugin.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"os"
 	"path"
+	"path/filepath"
 	"regexp"
 	"sort"
 	"strings"
@@ -39,6 +40,7 @@ const (
 	devfsDriDirectory = "/dev/dri"
 	gpuDeviceRE       = `^card[0-9]+$`
 	controlDeviceRE   = `^controlD[0-9]+$`
+	pciAddressRE      = "^[0-9a-f]{4}:[0-9a-f]{2}:[0-9a-f]{2}\\.[0-9a-f]{1}$"
 	vendorString      = "0x8086"
 
 	// Device plugin settings.
@@ -145,32 +147,85 @@ func packedPolicy(req *pluginapi.ContainerPreferredAllocationRequest) []string {
 	return deviceIds
 }
 
+// Returns a slice of by-path Mounts for a cardPath&Name.
+// by-path files are searched from the given bypathDir.
+// In the by-path dir, any files that start with "pci-<pci addr>" will be added to mounts.
+func (dp *devicePlugin) bypathMountsForPci(cardPath, cardName, bypathDir string) []pluginapi.Mount {
+	linkPath, err := os.Readlink(cardPath)
+	if err != nil {
+		return nil
+	}
+
+	// Fetches the pci address for a drm card by reading the
+	// symbolic link that the /sys/class/drm/cardX points to.
+	// ../../devices/pci0000:00/0000:00:02.0/drm/card
+	// -------------------------^^^^^^^^^^^^---------.
+	pciAddress := filepath.Base(strings.TrimSuffix(linkPath, filepath.Join("drm", cardName)))
+
+	if !dp.pciAddressReg.MatchString(pciAddress) {
+		klog.Warningf("Invalid pci address for %s: %s", cardPath, pciAddress)
+
+		return nil
+	}
+
+	files, err := os.ReadDir(bypathDir)
+	if err != nil {
+		klog.Warningf("Failed to read by-path directory: %+v", err)
+
+		return nil
+	}
+
+	linkPrefix := "pci-" + pciAddress
+
+	var mounts []pluginapi.Mount
+
+	for _, f := range files {
+		if strings.HasPrefix(f.Name(), linkPrefix) {
+			absPath := path.Join(bypathDir, f.Name())
+			mounts = append(mounts, pluginapi.Mount{
+				ContainerPath: absPath,
+				HostPath:      absPath,
+				ReadOnly:      true,
+			})
+		}
+	}
+
+	return mounts
+}
+
 type devicePlugin struct {
 	gpuDeviceReg     *regexp.Regexp
 	controlDeviceReg *regexp.Regexp
+	pciAddressReg    *regexp.Regexp
 
 	scanTicker *time.Ticker
 	scanDone   chan bool
 
 	resMan rm.ResourceManager
 
-	sysfsDir string
-	devfsDir string
+	sysfsDir  string
+	devfsDir  string
+	bypathDir string
 
 	// Note: If restarting the plugin with a new policy, the allocations for existing pods remain with old policy.
 	policy  preferredAllocationPolicyFunc
 	options cliOptions
+
+	bypathFound bool
 }
 
 func newDevicePlugin(sysfsDir, devfsDir string, options cliOptions) *devicePlugin {
 	dp := &devicePlugin{
 		sysfsDir:         sysfsDir,
 		devfsDir:         devfsDir,
+		bypathDir:        path.Join(devfsDir, "/by-path"),
 		options:          options,
 		gpuDeviceReg:     regexp.MustCompile(gpuDeviceRE),
 		controlDeviceReg: regexp.MustCompile(controlDeviceRE),
+		pciAddressReg:    regexp.MustCompile(pciAddressRE),
 		scanTicker:       time.NewTicker(scanPeriod),
 		scanDone:         make(chan bool, 1), // buffered as we may send to it before Scan starts receiving from it
+		bypathFound:      true,
 	}
 
 	if options.resourceManagement {
@@ -192,6 +247,12 @@ func newDevicePlugin(sysfsDir, devfsDir string, options cliOptions) *devicePlugi
 		dp.policy = nonePolicy
 	}
 
+	if _, err := os.ReadDir(dp.bypathDir); err != nil {
+		klog.Warningf("failed to read by-path dir: $+v", err)
+
+		dp.bypathFound = false
+	}
+
 	return dp
 }
 
@@ -299,7 +360,9 @@ func (dp *devicePlugin) scan() (dpapi.DeviceTree, error) {
 			continue
 		}
 
-		drmFiles, err := os.ReadDir(path.Join(dp.sysfsDir, f.Name(), "device/drm"))
+		cardPath := path.Join(dp.sysfsDir, f.Name())
+
+		drmFiles, err := os.ReadDir(path.Join(cardPath, "device/drm"))
 		if err != nil {
 			return nil, errors.Wrap(err, "Can't read device folder")
 		}
@@ -338,15 +401,20 @@ func (dp *devicePlugin) scan() (dpapi.DeviceTree, error) {
 		}
 
 		if len(nodes) > 0 {
-			deviceInfo := dpapi.NewDeviceInfo(pluginapi.Healthy, nodes, nil, nil, nil)
+			mounts := []pluginapi.Mount{}
+			if dp.bypathFound {
+				mounts = dp.bypathMountsForPci(cardPath, f.Name(), dp.bypathDir)
+			}
+
+			deviceInfo := dpapi.NewDeviceInfo(pluginapi.Healthy, nodes, mounts, nil, nil)
 
 			for i := 0; i < dp.options.sharedDevNum; i++ {
 				devID := fmt.Sprintf("%s-%d", f.Name(), i)
 				// Currently only one device type (i915) is supported.
 				// TODO: check model ID to differentiate device models.
 				devTree.AddDevice(deviceType, devID, deviceInfo)
 
-				rmDevInfos[devID] = rm.NewDeviceInfo(nodes, nil, nil)
+				rmDevInfos[devID] = rm.NewDeviceInfo(nodes, mounts, nil)
 			}
 		}
 	}

cmd/gpu_plugin/gpu_plugin_test.go

@@ -18,11 +18,13 @@ import (
 	"flag"
 	"os"
 	"path"
+	"path/filepath"
 	"reflect"
 	"testing"
 
 	"github.com/pkg/errors"
 	"k8s.io/kubelet/pkg/apis/deviceplugin/v1beta1"
+	"k8s.io/utils/strings/slices"
 
 	"github.com/intel/intel-device-plugins-for-kubernetes/cmd/gpu_plugin/rm"
 	dpapi "github.com/intel/intel-device-plugins-for-kubernetes/pkg/deviceplugin"
@@ -43,6 +45,7 @@ type mockNotifier struct {
 func (n *mockNotifier) Notify(newDeviceTree dpapi.DeviceTree) {
 	n.monitorCount = len(newDeviceTree[monitorType])
 	n.devCount = len(newDeviceTree[deviceType])
+
 	n.scanDone <- true
 }
 
@@ -190,7 +193,11 @@ func TestScan(t *testing.T) {
 			sysfsfiles: map[string][]byte{
 				"card0/device/vendor": []byte("0x8086"),
 			},
-			devfsdirs:    []string{"card0"},
+			devfsdirs: []string{
+				"card0",
+				"by-path/pci-0000:00:00.0-card",
+				"by-path/pci-0000:00:00.0-render",
+			},
 			expectedDevs: 1,
 		},
 		{
@@ -314,3 +321,126 @@ func TestScan(t *testing.T) {
 		})
 	}
 }
+
+// Would be nice to combine these with the overall Scan unit tests.
+func createBypathTestFiles(t *testing.T, card, root, linkFile string, bypathFiles []string) (string, string) {
+	drmPath := path.Join(root, "sys/class/drm/", card)
+	devPath := path.Join(root, "sys", linkFile)
+	byPath := path.Join(root, "by-path")
+
+	if linkFile != "" {
+		if err := os.MkdirAll(filepath.Dir(devPath), os.ModePerm); err != nil {
+			t.Fatal("Couldn't create test dev dir", err)
+		}
+
+		if err := os.MkdirAll(filepath.Dir(drmPath), os.ModePerm); err != nil {
+			t.Fatal("Couldn't create test drm dir", err)
+		}
+
+		if err := os.WriteFile(devPath, []byte{0}, os.ModePerm); err != nil {
+			t.Fatal("Couldn't create card file", err)
+		}
+
+		if err := os.Symlink(devPath, drmPath); err != nil {
+			t.Fatal("Couldn't create symlink between pci path and sysfs drm path")
+		}
+	}
+
+	if len(bypathFiles) > 0 {
+		if err := os.MkdirAll(byPath, os.ModePerm); err != nil {
+			t.Fatal("Mkdir failed:", byPath)
+		}
+
+		for _, f := range bypathFiles {
+			if err := os.WriteFile(path.Join(byPath, f), []byte{1}, os.ModePerm); err != nil {
+				t.Fatal("WriteFile failed:", path.Join(byPath, f))
+			}
+		}
+	}
+
+	return drmPath, byPath
+}
+
+func TestBypath(t *testing.T) {
+	type testData struct {
+		desc        string
+		linkpath    string
+		bypathFiles []string
+		mountCount  int
+	}
+
+	const cardName string = "card0"
+
+	tds := []testData{
+		{
+			"card with two by-path files",
+			"00.10.2/00.334.302/0.0.1.00/0000:0f:05.0/drm/" + cardName,
+			[]string{"pci-0000:0f:05.0-card", "pci-0000:0f:05.0-render"},
+			2,
+		},
+		{
+			"different by-path files",
+			"00.10.2/00.334.302/0.0.1.00/0000:ff:05.0/drm/" + cardName,
+			[]string{"pci-0000:0f:05.0-card", "pci-0000:0f:05.0-render"},
+			0,
+		},
+		{
+			"invalid pci address",
+			"00.10.2/00.334.302/0.0.1.00/000:ff:05.1/drm/" + cardName,
+			[]string{"pci-0000:0f:05.0-card", "pci-0000:0f:05.0-render"},
+			0,
+		},
+		{
+			"symlink without card",
+			"00.10.2/00.334.302/0.0.1.00/0000:0f:05.0/drm",
+			[]string{"pci-0000:0f:05.0-card", "pci-0000:0f:05.0-render"},
+			0,
+		},
+		{
+			"no symlink",
+			"",
+			[]string{"pci-0000:0f:05.0-card", "pci-0000:0f:05.0-render"},
+			0,
+		},
+		{
+			"no by-path files",
+			"00.10.2/00.334.302/0.0.1.00/0000:0f:05.0/drm/" + cardName,
+			[]string{},
+			0,
+		},
+	}
+
+	for _, td := range tds {
+		root, err := os.MkdirTemp("", "test_bypath_mounting")
+		if err != nil {
+			t.Fatalf("can't create temporary directory: %+v", err)
+		}
+		// dirs/files need to be removed for the next test
+		defer os.RemoveAll(root)
+
+		plugin := newDevicePlugin("/", "/", cliOptions{})
+
+		drmPath, byPath := createBypathTestFiles(t, cardName, root, td.linkpath, td.bypathFiles)
+
+		mounts := plugin.bypathMountsForPci(drmPath, cardName, byPath)
+
+		if len(mounts) != td.mountCount {
+			t.Errorf("%s: Wrong number of mounts %d vs. %d", td.desc, len(mounts), td.mountCount)
+		}
+
+		absPaths := []string{}
+		for _, link := range td.bypathFiles {
+			absPaths = append(absPaths, path.Join(byPath, link))
+		}
+
+		for _, mount := range mounts {
+			if !slices.Contains(absPaths, mount.ContainerPath) {
+				t.Errorf("%s: containerpath is incorrect: %s", td.desc, mount.ContainerPath)
+			}
+
+			if !slices.Contains(absPaths, mount.HostPath) {
+				t.Errorf("%s: hostpath is incorrect: %s", td.desc, mount.HostPath)
+			}
+		}
+	}
+}