88 lines
2.6 KiB
Go
88 lines
2.6 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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package kvm
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import (
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"gvisor.dev/gvisor/pkg/sentry/arch"
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"gvisor.dev/gvisor/pkg/sentry/platform"
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"gvisor.dev/gvisor/pkg/sentry/platform/interrupt"
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"gvisor.dev/gvisor/pkg/sentry/platform/ring0"
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"gvisor.dev/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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// info is the arch.SignalInfo cached for this context.
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info arch.SignalInfo
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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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localAS := as.(*addressSpace)
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// Grab a vCPU.
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cpu := c.machine.Get()
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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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// Set the active address space.
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//
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// This must be done prior to the call to Touch below. If the address
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// space is invalidated between this line and the call below, we will
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// flag on entry anyways. When the active address space below is
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// cleared, it indicates that we don't need an explicit interrupt and
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// that the flush can occur naturally on the next user entry.
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cpu.active.set(localAS)
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// Prepare switch options.
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switchOpts := ring0.SwitchOpts{
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Registers: &ac.StateData().Regs,
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FloatingPointState: (*byte)(ac.FloatingPointData()),
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PageTables: localAS.pageTables,
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Flush: localAS.Touch(cpu),
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FullRestore: ac.FullRestore(),
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}
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// Take the blue pill.
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at, err := cpu.SwitchToUser(switchOpts, &c.info)
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// Clear the address space.
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cpu.active.set(nil)
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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 &c.info, 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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