82 lines
2.3 KiB
Go
82 lines
2.3 KiB
Go
// Copyright 2018 Google Inc.
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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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package kvm
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import (
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"sync/atomic"
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"gvisor.googlesource.com/gvisor/pkg/sentry/arch"
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"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
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"gvisor.googlesource.com/gvisor/pkg/sentry/platform/interrupt"
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"gvisor.googlesource.com/gvisor/pkg/sentry/platform/ring0"
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"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
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)
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// context is an implementation of the platform context.
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//
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// This is a thin wrapper around the machine.
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type context struct {
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// machine is the parent machine, and is immutable.
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machine *machine
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// interrupt is the interrupt context.
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interrupt interrupt.Forwarder
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}
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// Switch runs the provided context in the given address space.
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func (c *context) Switch(as platform.AddressSpace, ac arch.Context, _ int32) (*arch.SignalInfo, usermem.AccessType, error) {
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// Extract data.
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localAS := as.(*addressSpace)
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regs := &ac.StateData().Regs
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fp := (*byte)(ac.FloatingPointData())
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// Grab a vCPU.
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cpu, err := c.machine.Get()
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if err != nil {
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return nil, usermem.NoAccess, err
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}
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// Enable interrupts (i.e. calls to vCPU.Notify).
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if !c.interrupt.Enable(cpu) {
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c.machine.Put(cpu) // Already preempted.
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return nil, usermem.NoAccess, platform.ErrContextInterrupt
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}
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// Mark the address space as dirty.
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flags := ring0.Flags(0)
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dirty := localAS.Touch(cpu)
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if v := atomic.SwapUint32(dirty, 1); v == 0 {
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flags |= ring0.FlagFlush
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}
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if ac.FullRestore() {
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flags |= ring0.FlagFull
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}
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// Take the blue pill.
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si, at, err := cpu.SwitchToUser(regs, fp, localAS.pageTables, flags)
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// Release resources.
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c.machine.Put(cpu)
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// All done.
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c.interrupt.Disable()
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return si, at, err
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}
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// Interrupt interrupts the running context.
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func (c *context) Interrupt() {
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c.interrupt.NotifyInterrupt()
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}
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