Merge 216da0b7 (automated)

1 files changed, 160 insertions, 0 deletions

diff --git a/pkg/sentry/platform/kvm/machine_unsafe.go b/pkg/sentry/platform/kvm/machine_unsafe.go
new file mode 100644
index 000000000..1d3c6d2d6
--- /dev/null
+++ b/pkg/sentry/platform/kvm/machine_unsafe.go
@@ -0,0 +1,160 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build go1.12
+// +build !go1.14
+
+// Check go:linkname function signatures when updating Go version.
+
+package kvm
+
+import (
+	"fmt"
+	"sync/atomic"
+	"syscall"
+	"unsafe"
+
+	"gvisor.googlesource.com/gvisor/pkg/abi/linux"
+)
+
+//go:linkname entersyscall runtime.entersyscall
+func entersyscall()
+
+//go:linkname exitsyscall runtime.exitsyscall
+func exitsyscall()
+
+// mapRunData maps the vCPU run data.
+func mapRunData(fd int) (*runData, error) {
+	r, _, errno := syscall.RawSyscall6(
+		syscall.SYS_MMAP,
+		0,
+		uintptr(runDataSize),
+		syscall.PROT_READ|syscall.PROT_WRITE,
+		syscall.MAP_SHARED,
+		uintptr(fd),
+		0)
+	if errno != 0 {
+		return nil, fmt.Errorf("error mapping runData: %v", errno)
+	}
+	return (*runData)(unsafe.Pointer(r)), nil
+}
+
+// unmapRunData unmaps the vCPU run data.
+func unmapRunData(r *runData) error {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_MUNMAP,
+		uintptr(unsafe.Pointer(r)),
+		uintptr(runDataSize),
+		0); errno != 0 {
+		return fmt.Errorf("error unmapping runData: %v", errno)
+	}
+	return nil
+}
+
+// setUserRegisters sets user registers in the vCPU.
+func (c *vCPU) setUserRegisters(uregs *userRegs) error {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_SET_REGS,
+		uintptr(unsafe.Pointer(uregs))); errno != 0 {
+		return fmt.Errorf("error setting user registers: %v", errno)
+	}
+	return nil
+}
+
+// getUserRegisters reloads user registers in the vCPU.
+//
+// This is safe to call from a nosplit context.
+//
+//go:nosplit
+func (c *vCPU) getUserRegisters(uregs *userRegs) syscall.Errno {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_GET_REGS,
+		uintptr(unsafe.Pointer(uregs))); errno != 0 {
+		return errno
+	}
+	return 0
+}
+
+// setSystemRegisters sets system registers.
+func (c *vCPU) setSystemRegisters(sregs *systemRegs) error {
+	if _, _, errno := syscall.RawSyscall(
+		syscall.SYS_IOCTL,
+		uintptr(c.fd),
+		_KVM_SET_SREGS,
+		uintptr(unsafe.Pointer(sregs))); errno != 0 {
+		return fmt.Errorf("error setting system registers: %v", errno)
+	}
+	return nil
+}
+
+// atomicAddressSpace is an atomic address space pointer.
+type atomicAddressSpace struct {
+	pointer unsafe.Pointer
+}
+
+// set sets the address space value.
+//
+//go:nosplit
+func (a *atomicAddressSpace) set(as *addressSpace) {
+	atomic.StorePointer(&a.pointer, unsafe.Pointer(as))
+}
+
+// get gets the address space value.
+//
+// Note that this should be considered best-effort, and may have changed by the
+// time this function returns.
+//
+//go:nosplit
+func (a *atomicAddressSpace) get() *addressSpace {
+	return (*addressSpace)(atomic.LoadPointer(&a.pointer))
+}
+
+// notify notifies that the vCPU has transitioned modes.
+//
+// This may be called by a signal handler and therefore throws on error.
+//
+//go:nosplit
+func (c *vCPU) notify() {
+	_, _, errno := syscall.RawSyscall6(
+		syscall.SYS_FUTEX,
+		uintptr(unsafe.Pointer(&c.state)),
+		linux.FUTEX_WAKE|linux.FUTEX_PRIVATE_FLAG,
+		^uintptr(0), // Number of waiters.
+		0, 0, 0)
+	if errno != 0 {
+		throw("futex wake error")
+	}
+}
+
+// waitUntilNot waits for the vCPU to transition modes.
+//
+// The state should have been previously set to vCPUWaiter after performing an
+// appropriate action to cause a transition (e.g. interrupt injection).
+//
+// This panics on error.
+func (c *vCPU) waitUntilNot(state uint32) {
+	_, _, errno := syscall.Syscall6(
+		syscall.SYS_FUTEX,
+		uintptr(unsafe.Pointer(&c.state)),
+		linux.FUTEX_WAIT|linux.FUTEX_PRIVATE_FLAG,
+		uintptr(state),
+		0, 0, 0)
+	if errno != 0 && errno != syscall.EINTR && errno != syscall.EAGAIN {
+		panic("futex wait error")
+	}
+}