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-rw-r--r--pkg/sentry/platform/kvm/bluepill_unsafe.go6
-rw-r--r--pkg/sentry/platform/kvm/context.go5
-rw-r--r--pkg/sentry/platform/kvm/machine.go18
3 files changed, 24 insertions, 5 deletions
diff --git a/pkg/sentry/platform/kvm/bluepill_unsafe.go b/pkg/sentry/platform/kvm/bluepill_unsafe.go
index 979be5d89..eb05950cd 100644
--- a/pkg/sentry/platform/kvm/bluepill_unsafe.go
+++ b/pkg/sentry/platform/kvm/bluepill_unsafe.go
@@ -62,6 +62,9 @@ func bluepillArchContext(context unsafe.Pointer) *arch.SignalContext64 {
//
//go:nosplit
func bluepillGuestExit(c *vCPU, context unsafe.Pointer) {
+ // Increment our counter.
+ atomic.AddUint64(&c.guestExits, 1)
+
// Copy out registers.
bluepillArchExit(c, bluepillArchContext(context))
@@ -89,9 +92,6 @@ func bluepillHandler(context unsafe.Pointer) {
// Sanitize the registers; interrupts must always be disabled.
c := bluepillArchEnter(bluepillArchContext(context))
- // Increment the number of switches.
- atomic.AddUint32(&c.switches, 1)
-
// Mark this as guest mode.
switch atomic.SwapUint32(&c.state, vCPUGuest|vCPUUser) {
case vCPUUser: // Expected case.
diff --git a/pkg/sentry/platform/kvm/context.go b/pkg/sentry/platform/kvm/context.go
index 6e6b76416..17268d127 100644
--- a/pkg/sentry/platform/kvm/context.go
+++ b/pkg/sentry/platform/kvm/context.go
@@ -15,6 +15,8 @@
package kvm
import (
+ "sync/atomic"
+
pkgcontext "gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/sentry/arch"
"gvisor.dev/gvisor/pkg/sentry/platform"
@@ -75,6 +77,9 @@ func (c *context) Switch(ctx pkgcontext.Context, mm platform.MemoryManager, ac a
// Clear the address space.
cpu.active.set(nil)
+ // Increment the number of user exits.
+ atomic.AddUint64(&cpu.userExits, 1)
+
// Release resources.
c.machine.Put(cpu)
diff --git a/pkg/sentry/platform/kvm/machine.go b/pkg/sentry/platform/kvm/machine.go
index 455e2bd20..61ed24d01 100644
--- a/pkg/sentry/platform/kvm/machine.go
+++ b/pkg/sentry/platform/kvm/machine.go
@@ -103,8 +103,11 @@ type vCPU struct {
// tid is the last set tid.
tid uint64
- // switches is a count of world switches (informational only).
- switches uint32
+ // userExits is the count of user exits.
+ userExits uint64
+
+ // guestExits is the count of guest to host world switches.
+ guestExits uint64
// faults is a count of world faults (informational only).
faults uint32
@@ -127,6 +130,7 @@ type vCPU struct {
// vCPUArchState is the architecture-specific state.
vCPUArchState
+ // dieState holds state related to vCPU death.
dieState dieState
}
@@ -540,6 +544,8 @@ var pid = syscall.Getpid()
//
// This effectively unwinds the state machine.
func (c *vCPU) bounce(forceGuestExit bool) {
+ origGuestExits := atomic.LoadUint64(&c.guestExits)
+ origUserExits := atomic.LoadUint64(&c.userExits)
for {
switch state := atomic.LoadUint32(&c.state); state {
case vCPUReady, vCPUWaiter:
@@ -595,6 +601,14 @@ func (c *vCPU) bounce(forceGuestExit bool) {
// Should not happen: the above is exhaustive.
panic("invalid state")
}
+
+ // Check if we've missed the state transition, but
+ // we can safely return at this point in time.
+ newGuestExits := atomic.LoadUint64(&c.guestExits)
+ newUserExits := atomic.LoadUint64(&c.userExits)
+ if newUserExits != origUserExits && (!forceGuestExit || newGuestExits != origGuestExits) {
+ return
+ }
}
}