arm64 kvm: add to ext_dabt injection support

If no vild syndrome(data abort outside memslots) was reported by kvm, let userspace to do the
ext_dabt injection to bail out this issue.

Signed-off-by: Robin Luk <lubin.lu@antgroup.com>

pkg/sentry/platform/kvm/bluepill_amd64_unsafe.go

@@ -91,6 +91,13 @@ func bluepillSigBus(c *vCPU) {
 	}
 }
 
+// bluepillHandleEnosys is reponsible for handling enosys error.
+//
+//go:nosplit
+func bluepillHandleEnosys(c *vCPU) {
+	throw("run failed: ENOSYS")
+}
+
 // bluepillReadyStopGuest checks whether the current vCPU is ready for interrupt injection.
 //
 //go:nosplit
@@ -126,3 +133,10 @@ func bluepillReadyStopGuest(c *vCPU) bool {
 	}
 	return true
 }
+
+// bluepillArchHandleExit checks architecture specific exitcode.
+//
+//go:nosplit
+func bluepillArchHandleExit(c *vCPU, context unsafe.Pointer) {
+	c.die(bluepillArchContext(context), "unknown")
+}

pkg/sentry/platform/kvm/bluepill_arm64.go

@@ -42,6 +42,13 @@ var (
 			sErrEsr:     _ESR_ELx_SERR_NMI,
 		},
 	}
+
+	// vcpuExtDabt is the event of ext_dabt.
+	vcpuExtDabt = kvmVcpuEvents{
+		exception: exception{
+			extDabtPending: 1,
+		},
+	}
 )
 
 // getTLS returns the value of TPIDR_EL0 register.

pkg/sentry/platform/kvm/bluepill_arm64_unsafe.go

@@ -85,7 +85,7 @@ func bluepillStopGuest(c *vCPU) {
 		uintptr(c.fd),
 		_KVM_SET_VCPU_EVENTS,
 		uintptr(unsafe.Pointer(&vcpuSErrBounce))); errno != 0 {
-		throw("sErr injection failed")
+		throw("bounce sErr injection failed")
 	}
 }
 
@@ -93,18 +93,54 @@ func bluepillStopGuest(c *vCPU) {
 //
 //go:nosplit
 func bluepillSigBus(c *vCPU) {
+	// Host must support ARM64_HAS_RAS_EXTN.
 	if _, _, errno := syscall.RawSyscall( // escapes: no.
 		syscall.SYS_IOCTL,
 		uintptr(c.fd),
 		_KVM_SET_VCPU_EVENTS,
 		uintptr(unsafe.Pointer(&vcpuSErrNMI))); errno != 0 {
-		throw("sErr injection failed")
+		if errno == syscall.EINVAL {
+			throw("No ARM64_HAS_RAS_EXTN feature in host.")
+		}
+		throw("nmi sErr injection failed")
 	}
 }
 
+// bluepillExtDabt is reponsible for injecting external data abort.
+//
+//go:nosplit
+func bluepillExtDabt(c *vCPU) {
+	if _, _, errno := syscall.RawSyscall( // escapes: no.
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_SET_VCPU_EVENTS,
+		uintptr(unsafe.Pointer(&vcpuExtDabt))); errno != 0 {
+		throw("ext_dabt injection failed")
+	}
+}
+
+// bluepillHandleEnosys is reponsible for handling enosys error.
+//
+//go:nosplit
+func bluepillHandleEnosys(c *vCPU) {
+	bluepillExtDabt(c)
+}
+
 // bluepillReadyStopGuest checks whether the current vCPU is ready for sError injection.
 //
 //go:nosplit
 func bluepillReadyStopGuest(c *vCPU) bool {
 	return true
 }
+
+// bluepillArchHandleExit checks architecture specific exitcode.
+//
+//go:nosplit
+func bluepillArchHandleExit(c *vCPU, context unsafe.Pointer) {
+	switch c.runData.exitReason {
+	case _KVM_EXIT_ARM_NISV:
+		bluepillExtDabt(c)
+	default:
+		c.die(bluepillArchContext(context), "unknown")
+	}
+}

pkg/sentry/platform/kvm/bluepill_unsafe.go

@@ -148,6 +148,9 @@ func bluepillHandler(context unsafe.Pointer) {
 			// mode and have interrupts disabled.
 			bluepillSigBus(c)
 			continue // Rerun vCPU.
+		case syscall.ENOSYS:
+			bluepillHandleEnosys(c)
+			continue
 		default:
 			throw("run failed")
 		}
@@ -220,7 +223,7 @@ func bluepillHandler(context unsafe.Pointer) {
 			c.die(bluepillArchContext(context), "entry failed")
 			return
 		default:
-			c.die(bluepillArchContext(context), "unknown")
+			bluepillArchHandleExit(c, context)
 			return
 		}
 	}

pkg/sentry/platform/kvm/kvm_arm64.go

@@ -47,10 +47,11 @@ type userRegs struct {
 }
 
 type exception struct {
-	sErrPending uint8
-	sErrHasEsr  uint8
-	pad         [6]uint8
-	sErrEsr     uint64
+	sErrPending    uint8
+	sErrHasEsr     uint8
+	extDabtPending uint8
+	pad            [5]uint8
+	sErrEsr        uint64
 }
 
 type kvmVcpuEvents struct {

pkg/sentry/platform/kvm/kvm_const.go

@@ -56,6 +56,7 @@ const (
 	_KVM_EXIT_FAIL_ENTRY      = 0x9
 	_KVM_EXIT_INTERNAL_ERROR  = 0x11
 	_KVM_EXIT_SYSTEM_EVENT    = 0x18
+	_KVM_EXIT_ARM_NISV        = 0x1c
 )
 
 // KVM capability options.