163 lines
3.9 KiB
Go
163 lines
3.9 KiB
Go
// Copyright 2018 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// +build amd64
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package kvm
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import (
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"fmt"
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"sync/atomic"
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"unsafe"
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"golang.org/x/sys/unix"
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"gvisor.dev/gvisor/pkg/abi/linux"
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)
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// loadSegments copies the current segments.
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//
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// This may be called from within the signal context and throws on error.
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//
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//go:nosplit
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func (c *vCPU) loadSegments(tid uint64) {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_ARCH_PRCTL,
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linux.ARCH_GET_FS,
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uintptr(unsafe.Pointer(&c.CPU.Registers().Fs_base)),
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0); errno != 0 {
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throw("getting FS segment")
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}
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if _, _, errno := unix.RawSyscall(
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unix.SYS_ARCH_PRCTL,
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linux.ARCH_GET_GS,
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uintptr(unsafe.Pointer(&c.CPU.Registers().Gs_base)),
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0); errno != 0 {
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throw("getting GS segment")
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}
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atomic.StoreUint64(&c.tid, tid)
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}
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// setCPUID sets the CPUID to be used by the guest.
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func (c *vCPU) setCPUID() error {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_SET_CPUID2,
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uintptr(unsafe.Pointer(&cpuidSupported))); errno != 0 {
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return fmt.Errorf("error setting CPUID: %v", errno)
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}
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return nil
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}
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// getTSCFreq gets the TSC frequency.
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//
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// If mustSucceed is true, then this function panics on error.
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func (c *vCPU) getTSCFreq() (uintptr, error) {
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rawFreq, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_GET_TSC_KHZ,
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0 /* ignored */)
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if errno != 0 {
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return 0, errno
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}
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return rawFreq, nil
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}
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// setTSCFreq sets the TSC frequency.
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func (c *vCPU) setTSCFreq(freq uintptr) error {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_SET_TSC_KHZ,
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freq /* khz */); errno != 0 {
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return fmt.Errorf("error setting TSC frequency: %v", errno)
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}
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return nil
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}
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// setTSC sets the TSC value.
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func (c *vCPU) setTSC(value uint64) error {
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const _MSR_IA32_TSC = 0x00000010
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registers := modelControlRegisters{
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nmsrs: 1,
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}
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registers.entries[0].index = _MSR_IA32_TSC
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registers.entries[0].data = value
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_SET_MSRS,
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uintptr(unsafe.Pointer(®isters))); errno != 0 {
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return fmt.Errorf("error setting tsc: %v", errno)
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}
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return nil
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}
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// setUserRegisters sets user registers in the vCPU.
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//
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//go:nosplit
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func (c *vCPU) setUserRegisters(uregs *userRegs) unix.Errno {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_SET_REGS,
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uintptr(unsafe.Pointer(uregs))); errno != 0 {
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return errno
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}
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return 0
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}
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// getUserRegisters reloads user registers in the vCPU.
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//
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// This is safe to call from a nosplit context.
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//
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//go:nosplit
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func (c *vCPU) getUserRegisters(uregs *userRegs) unix.Errno {
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if _, _, errno := unix.RawSyscall( // escapes: no.
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_GET_REGS,
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uintptr(unsafe.Pointer(uregs))); errno != 0 {
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return errno
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}
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return 0
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}
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// setSystemRegisters sets system registers.
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func (c *vCPU) setSystemRegisters(sregs *systemRegs) error {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_SET_SREGS,
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uintptr(unsafe.Pointer(sregs))); errno != 0 {
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return fmt.Errorf("error setting system registers: %v", errno)
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}
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return nil
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}
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// getSystemRegisters sets system registers.
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//
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//go:nosplit
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func (c *vCPU) getSystemRegisters(sregs *systemRegs) unix.Errno {
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if _, _, errno := unix.RawSyscall(
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unix.SYS_IOCTL,
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uintptr(c.fd),
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_KVM_GET_SREGS,
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uintptr(unsafe.Pointer(sregs))); errno != 0 {
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return errno
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}
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return 0
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}
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