1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
// 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.
// Package kvm provides a kvm-based implementation of the platform interface.
package kvm
import (
"fmt"
"os"
"syscall"
"gvisor.dev/gvisor/pkg/sentry/platform"
"gvisor.dev/gvisor/pkg/sentry/platform/ring0"
"gvisor.dev/gvisor/pkg/sentry/platform/ring0/pagetables"
"gvisor.dev/gvisor/pkg/sync"
"gvisor.dev/gvisor/pkg/usermem"
)
// userMemoryRegion is a region of physical memory.
//
// This mirrors kvm_memory_region.
type userMemoryRegion struct {
slot uint32
flags uint32
guestPhysAddr uint64
memorySize uint64
userspaceAddr uint64
}
// runData is the run structure. This may be mapped for synchronous register
// access (although that doesn't appear to be supported by my kernel at least).
//
// This mirrors kvm_run.
type runData struct {
requestInterruptWindow uint8
_ [7]uint8
exitReason uint32
readyForInterruptInjection uint8
ifFlag uint8
_ [2]uint8
cr8 uint64
apicBase uint64
// This is the union data for exits. Interpretation depends entirely on
// the exitReason above (see vCPU code for more information).
data [32]uint64
}
// KVM represents a lightweight VM context.
type KVM struct {
platform.NoCPUPreemptionDetection
// KVM never changes mm_structs.
platform.UseHostProcessMemoryBarrier
// machine is the backing VM.
machine *machine
}
var (
globalOnce sync.Once
globalErr error
)
// OpenDevice opens the KVM device at /dev/kvm and returns the File.
func OpenDevice() (*os.File, error) {
f, err := os.OpenFile("/dev/kvm", syscall.O_RDWR, 0)
if err != nil {
return nil, fmt.Errorf("error opening /dev/kvm: %v", err)
}
return f, nil
}
// New returns a new KVM-based implementation of the platform interface.
func New(deviceFile *os.File) (*KVM, error) {
fd := deviceFile.Fd()
// Ensure global initialization is done.
globalOnce.Do(func() {
globalErr = updateGlobalOnce(int(fd))
})
if globalErr != nil {
return nil, globalErr
}
// Create a new VM fd.
var (
vm uintptr
errno syscall.Errno
)
for {
vm, _, errno = syscall.Syscall(syscall.SYS_IOCTL, fd, _KVM_CREATE_VM, 0)
if errno == syscall.EINTR {
continue
}
if errno != 0 {
return nil, fmt.Errorf("creating VM: %v", errno)
}
break
}
// We are done with the device file.
deviceFile.Close()
// Create a VM context.
machine, err := newMachine(int(vm))
if err != nil {
return nil, err
}
// All set.
return &KVM{
machine: machine,
}, nil
}
// SupportsAddressSpaceIO implements platform.Platform.SupportsAddressSpaceIO.
func (*KVM) SupportsAddressSpaceIO() bool {
return false
}
// CooperativelySchedulesAddressSpace implements platform.Platform.CooperativelySchedulesAddressSpace.
func (*KVM) CooperativelySchedulesAddressSpace() bool {
return false
}
// MapUnit implements platform.Platform.MapUnit.
func (*KVM) MapUnit() uint64 {
// We greedily creates PTEs in MapFile, so extremely large mappings can
// be expensive. Not _that_ expensive since we allow super pages, but
// even though can get out of hand if you're creating multi-terabyte
// mappings. For this reason, we limit mappings to an arbitrary 16MB.
return 16 << 20
}
// MinUserAddress returns the lowest available address.
func (*KVM) MinUserAddress() usermem.Addr {
return usermem.PageSize
}
// MaxUserAddress returns the first address that may not be used.
func (*KVM) MaxUserAddress() usermem.Addr {
return usermem.Addr(ring0.MaximumUserAddress)
}
// NewAddressSpace returns a new pagetable root.
func (k *KVM) NewAddressSpace(_ interface{}) (platform.AddressSpace, <-chan struct{}, error) {
// Allocate page tables and install system mappings.
pageTables := pagetables.NewWithUpper(newAllocator(), k.machine.upperSharedPageTables, ring0.KernelStartAddress)
// Return the new address space.
return &addressSpace{
machine: k.machine,
pageTables: pageTables,
dirtySet: k.machine.newDirtySet(),
}, nil, nil
}
// NewContext returns an interruptible context.
func (k *KVM) NewContext() platform.Context {
return &context{
machine: k.machine,
}
}
type constructor struct{}
func (*constructor) New(f *os.File) (platform.Platform, error) {
return New(f)
}
func (*constructor) OpenDevice() (*os.File, error) {
return OpenDevice()
}
// Flags implements platform.Constructor.Flags().
func (*constructor) Requirements() platform.Requirements {
return platform.Requirements{}
}
func init() {
platform.Register("kvm", &constructor{})
}
|
