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
|
// Copyright 2018 Google Inc.
//
// 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"
"sync"
"syscall"
"gvisor.googlesource.com/gvisor/pkg/cpuid"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform/filemem"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform/ring0"
"gvisor.googlesource.com/gvisor/pkg/sentry/platform/ring0/pagetables"
"gvisor.googlesource.com/gvisor/pkg/sentry/usermem"
)
// KVM represents a lightweight VM context.
type KVM struct {
platform.NoCPUPreemptionDetection
// filemem is our memory source.
*filemem.FileMem
// machine is the backing VM.
machine *machine
}
var (
globalOnce sync.Once
globalErr error
)
// New returns a new KVM-based implementation of the platform interface.
func New() (*KVM, error) {
// Allocate physical memory for the vCPUs.
fm, err := filemem.New("kvm-memory")
if err != nil {
return nil, err
}
// Try opening KVM.
fd, err := syscall.Open("/dev/kvm", syscall.O_RDWR, 0)
if err != nil {
return nil, fmt.Errorf("opening /dev/kvm: %v", err)
}
defer syscall.Close(fd)
// Ensure global initialization is done.
globalOnce.Do(func() {
physicalInit()
globalErr = updateSystemValues(fd)
ring0.Init(cpuid.HostFeatureSet())
})
if globalErr != nil {
return nil, globalErr
}
// Create a new VM fd.
vm, _, errno := syscall.RawSyscall(syscall.SYS_IOCTL, uintptr(fd), _KVM_CREATE_VM, 0)
if errno != 0 {
return nil, fmt.Errorf("creating VM: %v", errno)
}
// Create a VM context.
machine, err := newMachine(int(vm))
if err != nil {
return nil, err
}
// All set.
return &KVM{
FileMem: fm,
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.New(newAllocator())
applyPhysicalRegions(func(pr physicalRegion) bool {
// Map the kernel in the upper half.
pageTables.Map(
usermem.Addr(ring0.KernelStartAddress|pr.virtual),
pr.length,
pagetables.MapOpts{AccessType: usermem.AnyAccess},
pr.physical)
return true // Keep iterating.
})
// Return the new address space.
return &addressSpace{
filemem: k.FileMem,
machine: k.machine,
pageTables: pageTables,
}, nil, nil
}
// NewContext returns an interruptible context.
func (k *KVM) NewContext() platform.Context {
return &context{
machine: k.machine,
}
}
// Memory returns the platform memory used to do allocations.
func (k *KVM) Memory() platform.Memory {
return k.FileMem
}
|
