Merge release-20210419.0-17-g6f9db949d (automated)

3 files changed, 14 insertions, 0 deletions

diff --git a/pkg/sentry/platform/kvm/kvm_const.go b/pkg/sentry/platform/kvm/kvm_const.go
index 2492d57be..eb2dcccac 100644
--- a/pkg/sentry/platform/kvm/kvm_const.go
+++ b/pkg/sentry/platform/kvm/kvm_const.go
@@ -66,6 +66,7 @@ const (
 	_KVM_CAP_ARM_VM_IPA_SIZE       = 0xa5
 	_KVM_CAP_VCPU_EVENTS           = 0x29
 	_KVM_CAP_ARM_INJECT_SERROR_ESR = 0x9e
+	_KVM_CAP_TSC_CONTROL           = 0x3c
 )
 
 // KVM limits.
diff --git a/pkg/sentry/platform/kvm/machine.go b/pkg/sentry/platform/kvm/machine.go
index b3d4188a3..99f036bba 100644
--- a/pkg/sentry/platform/kvm/machine.go
+++ b/pkg/sentry/platform/kvm/machine.go
@@ -67,6 +67,9 @@ type machine struct {
 	// maxSlots is the maximum number of memory slots supported by the machine.
 	maxSlots int
 
+	// tscControl checks whether cpu supports TSC scaling
+	tscControl bool
+
 	// usedSlots is the set of used physical addresses (sorted).
 	usedSlots []uintptr
 
@@ -214,6 +217,11 @@ func newMachine(vm int) (*machine, error) {
 	log.Debugf("The maximum number of slots is %d.", m.maxSlots)
 	m.usedSlots = make([]uintptr, m.maxSlots)
 
+	// Check TSC Scaling
+	hasTSCControl, _, errno := unix.RawSyscall(unix.SYS_IOCTL, uintptr(m.fd), _KVM_CHECK_EXTENSION, _KVM_CAP_TSC_CONTROL)
+	m.tscControl = errno == 0 && hasTSCControl == 1
+	log.Debugf("TSC scaling support: %t.", m.tscControl)
+
 	// Create the upper shared pagetables and kernel(sentry) pagetables.
 	m.upperSharedPageTables = pagetables.New(newAllocator())
 	m.mapUpperHalf(m.upperSharedPageTables)
diff --git a/pkg/sentry/platform/kvm/machine_amd64.go b/pkg/sentry/platform/kvm/machine_amd64.go
index e8e209249..d7abfefb4 100644
--- a/pkg/sentry/platform/kvm/machine_amd64.go
+++ b/pkg/sentry/platform/kvm/machine_amd64.go
@@ -213,6 +213,11 @@ func (c *vCPU) setSystemTime() error {
 	// capabilities as it is emulated in KVM. We don't actually use this
 	// capability, but it means that this method should be robust to
 	// different hardware configurations.
+
+	// if tsc scaling is not supported, fallback to legacy mode
+	if !c.machine.tscControl {
+		return c.setSystemTimeLegacy()
+	}
 	rawFreq, err := c.getTSCFreq()
 	if err != nil {
 		return c.setSystemTimeLegacy()