clh,qemu: Adapt to using default_maxmemory

Let's adapt Cloud Hypervisor's and QEMU's code to properly behave to the
newly added `default_maxmemory` config.

While implementing this, a change of behaviour (or a bug fix, depending
on how you see it) has been introduced as if a pod requests more memory
than the amount avaiable in the host, instead of failing to start the
pod, we simply hotplug the maximum amount of memory available, mimicing
better the runc behaviour.

Fixes: #4516

Signed-off-by: Fabiano Fidêncio <fabiano.fidencio@intel.com>

src/runtime/virtcontainers/clh.go

@@ -480,12 +480,9 @@ func (clh *cloudHypervisor) CreateVM(ctx context.Context, id string, network Net
 	// Enable hugepages if needed
 	clh.vmconfig.Memory.Hugepages = func(b bool) *bool { return &b }(clh.config.HugePages)
 	if !clh.config.ConfidentialGuest {
-		hostMemKb, err := GetHostMemorySizeKb(procMemInfo)
+		hotplugSize := clh.config.DefaultMaxMemorySize
-		if err != nil {
-			return nil
-		}
 		// OpenAPI only supports int64 values
-		clh.vmconfig.Memory.HotplugSize = func(i int64) *int64 { return &i }(int64((utils.MemUnit(hostMemKb) * utils.KiB).ToBytes()))
+		clh.vmconfig.Memory.HotplugSize = func(i int64) *int64 { return &i }(int64((utils.MemUnit(hotplugSize) * utils.MiB).ToBytes()))
 	}
 	// Set initial amount of cpu's for the virtual machine
 	clh.vmconfig.Cpus = chclient.NewCpusConfig(int32(clh.config.NumVCPUs), int32(clh.config.DefaultMaxVCPUs))
@@ -882,6 +879,11 @@ func (clh *cloudHypervisor) ResizeMemory(ctx context.Context, reqMemMB uint32, m
 		return 0, MemoryDevice{}, err
 	}
 
+	maxHotplugSize := utils.MemUnit(*info.Config.Memory.HotplugSize) * utils.Byte
+	if reqMemMB > uint32(maxHotplugSize.ToMiB()) {
+		reqMemMB = uint32(maxHotplugSize.ToMiB())
+	}
+
 	currentMem := utils.MemUnit(info.Config.Memory.Size) * utils.Byte
 	newMem := utils.MemUnit(reqMemMB) * utils.MiB
 

src/runtime/virtcontainers/qemu.go

@@ -315,11 +315,7 @@ func (q *qemu) hostMemMB() (uint64, error) {
 }
 
 func (q *qemu) memoryTopology() (govmmQemu.Memory, error) {
-	hostMemMb, err := q.hostMemMB()
+	hostMemMb := q.config.DefaultMaxMemorySize
-	if err != nil {
-		return govmmQemu.Memory{}, err
-	}
-
 	memMb := uint64(q.config.MemorySize)
 
 	return q.arch.memoryTopology(memMb, hostMemMb, uint8(q.config.MemSlots)), nil
@@ -779,12 +775,8 @@ func (q *qemu) getMemArgs() (bool, string, string, error) {
 }
 
 func (q *qemu) setupVirtioMem(ctx context.Context) error {
-	maxMem, err := q.hostMemMB()
-	if err != nil {
-		return err
-	}
 	// backend memory size must be multiple of 4Mib
-	sizeMB := (int(maxMem) - int(q.config.MemorySize)) >> 2 << 2
+	sizeMB := (int(q.config.DefaultMaxMemorySize) - int(q.config.MemorySize)) >> 2 << 2
 
 	share, target, memoryBack, err := q.getMemArgs()
 	if err != nil {
@@ -1970,8 +1962,6 @@ func (q *qemu) hotplugMemory(memDev *MemoryDevice, op Operation) (int, error) {
 		return 0, err
 	}
 
-	currentMemory := int(q.config.MemorySize) + q.state.HotpluggedMemory
-
 	if memDev.SizeMB == 0 {
 		memLog.Debug("hotplug is not required")
 		return 0, nil
@@ -1985,17 +1975,7 @@ func (q *qemu) hotplugMemory(memDev *MemoryDevice, op Operation) (int, error) {
 		return 0, nil
 	case AddDevice:
 		memLog.WithField("operation", "add").Debugf("Requested to add memory: %d MB", memDev.SizeMB)
-		maxMem, err := q.hostMemMB()
-		if err != nil {
-			return 0, err
-		}
 
-		// Don't exceed the maximum amount of memory
-		if currentMemory+memDev.SizeMB > int(maxMem) {
-			// Fixme: return a typed error
-			return 0, fmt.Errorf("Unable to hotplug %d MiB memory, the SB has %d MiB and the maximum amount is %d MiB",
-				memDev.SizeMB, currentMemory, maxMem)
-		}
 		memoryAdded, err := q.hotplugAddMemory(memDev)
 		if err != nil {
 			return memoryAdded, err
@@ -2231,6 +2211,11 @@ func (q *qemu) ResizeMemory(ctx context.Context, reqMemMB uint32, memoryBlockSiz
 	case currentMemory < reqMemMB:
 		//hotplug
 		addMemMB := reqMemMB - currentMemory
+
+		if currentMemory+addMemMB > uint32(q.config.DefaultMaxMemorySize) {
+			addMemMB = uint32(q.config.DefaultMaxMemorySize) - currentMemory
+		}
+
 		memHotplugMB, err := calcHotplugMemMiBSize(addMemMB, memoryBlockSizeMB)
 		if err != nil {
 			return currentMemory, MemoryDevice{}, err

src/runtime/virtcontainers/qemu_test.go

@@ -21,6 +21,7 @@ import (
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/persist"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/types"
 	"github.com/kata-containers/kata-containers/src/runtime/virtcontainers/utils"
+	"github.com/pbnjay/memory"
 	"github.com/pkg/errors"
 	"github.com/stretchr/testify/assert"
 )
@@ -172,6 +173,7 @@ func TestQemuCPUTopology(t *testing.T) {
 
 func TestQemuMemoryTopology(t *testing.T) {
 	mem := uint32(1000)
+	maxMem := memory.TotalMemory() / 1024 / 1024 //MiB
 	slots := uint32(8)
 	assert := assert.New(t)
 
@@ -180,12 +182,11 @@ func TestQemuMemoryTopology(t *testing.T) {
 		config: HypervisorConfig{
 			MemorySize:           mem,
 			MemSlots:             slots,
+			DefaultMaxMemorySize: maxMem,
 		},
 	}
 
-	hostMemKb, err := GetHostMemorySizeKb(procMemInfo)
+	memMax := fmt.Sprintf("%dM", int(maxMem))
-	assert.NoError(err)
-	memMax := fmt.Sprintf("%dM", int(float64(hostMemKb)/1024))
 
 	expectedOut := govmmQemu.Memory{
 		Size:   fmt.Sprintf("%dM", mem),