1 files changed, 111 insertions, 3 deletions
diff --git a/pkg/sentry/fsimpl/cgroupfs/cpuset.go b/pkg/sentry/fsimpl/cgroupfs/cpuset.go
index ac547f8e2..62e7029da 100644
--- a/pkg/sentry/fsimpl/cgroupfs/cpuset.go
+++ b/pkg/sentry/fsimpl/cgroupfs/cpuset.go
@@ -15,25 +15,133 @@
 package cgroupfs
 
 import (
+	"bytes"
+	"fmt"
+
+	"gvisor.dev/gvisor/pkg/bitmap"
 	"gvisor.dev/gvisor/pkg/context"
+	"gvisor.dev/gvisor/pkg/errors/linuxerr"
+	"gvisor.dev/gvisor/pkg/hostarch"
+	"gvisor.dev/gvisor/pkg/log"
 	"gvisor.dev/gvisor/pkg/sentry/fsimpl/kernfs"
+	"gvisor.dev/gvisor/pkg/sentry/kernel"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // +stateify savable
 type cpusetController struct {
 	controllerCommon
+
+	maxCpus uint32
+	maxMems uint32
+
+	cpus *bitmap.Bitmap
+	mems *bitmap.Bitmap
 }
 
 var _ controller = (*cpusetController)(nil)
 
-func newCPUSetController(fs *filesystem) *cpusetController {
-	c := &cpusetController{}
+func newCPUSetController(k *kernel.Kernel, fs *filesystem) *cpusetController {
+	cores := uint32(k.ApplicationCores())
+	cpus := bitmap.New(cores)
+	cpus.FlipRange(0, cores)
+	mems := bitmap.New(1)
+	mems.FlipRange(0, 1)
+	c := &cpusetController{
+		cpus:    &cpus,
+		mems:    &mems,
+		maxCpus: uint32(k.ApplicationCores()),
+		maxMems: 1, // We always report a single NUMA node.
+	}
 	c.controllerCommon.init(controllerCPUSet, fs)
 	return c
 }
 
 // AddControlFiles implements controller.AddControlFiles.
 func (c *cpusetController) AddControlFiles(ctx context.Context, creds *auth.Credentials, _ *cgroupInode, contents map[string]kernfs.Inode) {
-	// This controller is currently intentionally empty.
+	contents["cpuset.cpus"] = c.fs.newControllerWritableFile(ctx, creds, &cpusData{c: c})
+	contents["cpuset.mems"] = c.fs.newControllerWritableFile(ctx, creds, &memsData{c: c})
+}
+
+// +stateify savable
+type cpusData struct {
+	c *cpusetController
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *cpusData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	fmt.Fprintf(buf, "%s\n", formatBitmap(d.c.cpus))
+	return nil
+}
+
+// Write implements vfs.WritableDynamicBytesSource.Write.
+func (d *cpusData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
+	src = src.DropFirst64(offset)
+	if src.NumBytes() > hostarch.PageSize {
+		return 0, linuxerr.EINVAL
+	}
+
+	t := kernel.TaskFromContext(ctx)
+	buf := t.CopyScratchBuffer(hostarch.PageSize)
+	n, err := src.CopyIn(ctx, buf)
+	if err != nil {
+		return 0, err
+	}
+	buf = buf[:n]
+
+	b, err := parseBitmap(string(buf), d.c.maxCpus)
+	if err != nil {
+		log.Warningf("cgroupfs cpuset controller: Failed to parse bitmap: %v", err)
+		return 0, linuxerr.EINVAL
+	}
+
+	if got, want := b.Maximum(), d.c.maxCpus; got > want {
+		log.Warningf("cgroupfs cpuset controller: Attempted to specify cpuset.cpus beyond highest available cpu: got %d, want %d", got, want)
+		return 0, linuxerr.EINVAL
+	}
+
+	d.c.cpus = b
+	return int64(n), nil
+}
+
+// +stateify savable
+type memsData struct {
+	c *cpusetController
+}
+
+// Generate implements vfs.DynamicBytesSource.Generate.
+func (d *memsData) Generate(ctx context.Context, buf *bytes.Buffer) error {
+	fmt.Fprintf(buf, "%s\n", formatBitmap(d.c.mems))
+	return nil
+}
+
+// Write implements vfs.WritableDynamicBytesSource.Write.
+func (d *memsData) Write(ctx context.Context, src usermem.IOSequence, offset int64) (int64, error) {
+	src = src.DropFirst64(offset)
+	if src.NumBytes() > hostarch.PageSize {
+		return 0, linuxerr.EINVAL
+	}
+
+	t := kernel.TaskFromContext(ctx)
+	buf := t.CopyScratchBuffer(hostarch.PageSize)
+	n, err := src.CopyIn(ctx, buf)
+	if err != nil {
+		return 0, err
+	}
+	buf = buf[:n]
+
+	b, err := parseBitmap(string(buf), d.c.maxMems)
+	if err != nil {
+		log.Warningf("cgroupfs cpuset controller: Failed to parse bitmap: %v", err)
+		return 0, linuxerr.EINVAL
+	}
+
+	if got, want := b.Maximum(), d.c.maxMems; got > want {
+		log.Warningf("cgroupfs cpuset controller: Attempted to specify cpuset.mems beyond highest available node: got %d, want %d", got, want)
+		return 0, linuxerr.EINVAL
+	}
+
+	d.c.mems = b
+	return int64(n), nil
 }