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
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
use crate::PAGE_SIZE;
use bitflags::*;
use volatile::{ReadOnly, Volatile, WriteOnly};

/// MMIO Device Legacy Register Interface.
///
/// Ref: 4.2.4 Legacy interface
#[repr(C)]
pub struct VirtIOHeader {
    /// Magic value
    magic: ReadOnly<u32>,

    /// Device version number
    ///
    /// Legacy device returns value 0x1.
    version: ReadOnly<u32>,

    /// Virtio Subsystem Device ID
    device_id: ReadOnly<u32>,

    /// Virtio Subsystem Vendor ID
    vendor_id: ReadOnly<u32>,

    /// Flags representing features the device supports
    device_features: ReadOnly<u32>,

    /// Device (host) features word selection
    device_features_sel: WriteOnly<u32>,

    /// Reserved
    __r1: [ReadOnly<u32>; 2],

    /// Flags representing device features understood and activated by the driver
    driver_features: WriteOnly<u32>,

    /// Activated (guest) features word selection
    driver_features_sel: WriteOnly<u32>,

    /// Guest page size
    ///
    /// The driver writes the guest page size in bytes to the register during
    /// initialization, before any queues are used. This value should be a
    /// power of 2 and is used by the device to calculate the Guest address
    /// of the first queue page (see QueuePFN).
    guest_page_size: WriteOnly<u32>,

    /// Reserved
    __r2: ReadOnly<u32>,

    /// Virtual queue index
    ///
    /// Writing to this register selects the virtual queue that the following
    /// operations on the QueueNumMax, QueueNum, QueueAlign and QueuePFN
    /// registers apply to. The index number of the first queue is zero (0x0).
    queue_sel: WriteOnly<u32>,

    /// Maximum virtual queue size
    ///
    /// Reading from the register returns the maximum size of the queue the
    /// device is ready to process or zero (0x0) if the queue is not available.
    /// This applies to the queue selected by writing to QueueSel and is
    /// allowed only when QueuePFN is set to zero (0x0), so when the queue is
    /// not actively used.
    queue_num_max: ReadOnly<u32>,

    /// Virtual queue size
    ///
    /// Queue size is the number of elements in the queue. Writing to this
    /// register notifies the device what size of the queue the driver will use.
    /// This applies to the queue selected by writing to QueueSel.
    queue_num: WriteOnly<u32>,

    /// Used Ring alignment in the virtual queue
    ///
    /// Writing to this register notifies the device about alignment boundary
    /// of the Used Ring in bytes. This value should be a power of 2 and
    /// applies to the queue selected by writing to QueueSel.
    queue_align: WriteOnly<u32>,

    /// Guest physical page number of the virtual queue
    ///
    /// Writing to this register notifies the device about location of the
    /// virtual queue in the Guest’s physical address space. This value is
    /// the index number of a page starting with the queue Descriptor Table.
    /// Value zero (0x0) means physical address zero (0x00000000) and is illegal.
    /// When the driver stops using the queue it writes zero (0x0) to this
    /// register. Reading from this register returns the currently used page
    /// number of the queue, therefore a value other than zero (0x0) means that
    /// the queue is in use. Both read and write accesses apply to the queue
    /// selected by writing to QueueSel.
    queue_pfn: Volatile<u32>,

    /// new interface only
    queue_ready: Volatile<u32>,

    /// Reserved
    __r3: [ReadOnly<u32>; 2],

    /// Queue notifier
    queue_notify: WriteOnly<u32>,

    /// Reserved
    __r4: [ReadOnly<u32>; 3],

    /// Interrupt status
    interrupt_status: ReadOnly<u32>,

    /// Interrupt acknowledge
    interrupt_ack: WriteOnly<u32>,

    /// Reserved
    __r5: [ReadOnly<u32>; 2],

    /// Device status
    ///
    /// Reading from this register returns the current device status flags.
    /// Writing non-zero values to this register sets the status flags,
    /// indicating the OS/driver progress. Writing zero (0x0) to this register
    /// triggers a device reset. The device sets QueuePFN to zero (0x0) for
    /// all queues in the device. Also see 3.1 Device Initialization.
    status: Volatile<DeviceStatus>,

    /// Reserved
    __r6: [ReadOnly<u32>; 3],

    // new interface only since here
    queue_desc_low: WriteOnly<u32>,
    queue_desc_high: WriteOnly<u32>,

    /// Reserved
    __r7: [ReadOnly<u32>; 2],

    queue_avail_low: WriteOnly<u32>,
    queue_avail_high: WriteOnly<u32>,

    /// Reserved
    __r8: [ReadOnly<u32>; 2],

    queue_used_low: WriteOnly<u32>,
    queue_used_high: WriteOnly<u32>,

    /// Reserved
    __r9: [ReadOnly<u32>; 21],

    config_generation: ReadOnly<u32>,
}

impl VirtIOHeader {
    /// Verify a valid header.
    pub fn verify(&self) -> bool {
        self.magic.read() == 0x7472_6976 && self.version.read() == 1 && self.device_id.read() != 0
    }

    /// Get the device type.
    pub fn device_type(&self) -> DeviceType {
        match self.device_id.read() {
            x @ 1..=13 | x @ 16..=24 => unsafe { core::mem::transmute(x as u8) },
            _ => DeviceType::Invalid,
        }
    }

    /// Get the vendor ID.
    pub fn vendor_id(&self) -> u32 {
        self.vendor_id.read()
    }

    /// Begin initializing the device.
    ///
    /// Ref: virtio 3.1.1 Device Initialization
    pub fn begin_init(&mut self, negotiate_features: impl FnOnce(u64) -> u64) {
        self.status.write(DeviceStatus::ACKNOWLEDGE);
        self.status.write(DeviceStatus::DRIVER);

        let features = self.read_device_features();
        self.write_driver_features(negotiate_features(features));
        self.status.write(DeviceStatus::FEATURES_OK);

        self.guest_page_size.write(PAGE_SIZE as u32);
    }

    /// Finish initializing the device.
    pub fn finish_init(&mut self) {
        self.status.write(DeviceStatus::DRIVER_OK);
    }

    /// Read device features.
    fn read_device_features(&mut self) -> u64 {
        self.device_features_sel.write(0); // device features [0, 32)
        let mut device_features_bits = self.device_features.read().into();
        self.device_features_sel.write(1); // device features [32, 64)
        device_features_bits += (self.device_features.read() as u64) << 32;
        device_features_bits
    }

    /// Write device features.
    fn write_driver_features(&mut self, driver_features: u64) {
        self.driver_features_sel.write(0); // driver features [0, 32)
        self.driver_features.write(driver_features as u32);
        self.driver_features_sel.write(1); // driver features [32, 64)
        self.driver_features.write((driver_features >> 32) as u32);
    }

    /// Set queue.
    pub fn queue_set(&mut self, queue: u32, size: u32, align: u32, pfn: u32) {
        self.queue_sel.write(queue);
        self.queue_num.write(size);
        self.queue_align.write(align);
        self.queue_pfn.write(pfn);
    }

    /// Get guest physical page number of the virtual queue.
    pub fn queue_physical_page_number(&mut self, queue: u32) -> u32 {
        self.queue_sel.write(queue);
        self.queue_pfn.read()
    }

    /// Whether the queue is in used.
    pub fn queue_used(&mut self, queue: u32) -> bool {
        self.queue_physical_page_number(queue) != 0
    }

    /// Get the max size of queue.
    pub fn max_queue_size(&self) -> u32 {
        self.queue_num_max.read()
    }

    /// Notify device.
    pub fn notify(&mut self, queue: u32) {
        self.queue_notify.write(queue);
    }

    /// Acknowledge interrupt and return true if success.
    pub fn ack_interrupt(&mut self) -> bool {
        let interrupt = self.interrupt_status.read();
        if interrupt != 0 {
            self.interrupt_ack.write(interrupt);
            true
        } else {
            false
        }
    }

    /// Get the pointer to config space (at offset 0x100)
    pub fn config_space(&self) -> *mut u64 {
        (self as *const _ as usize + CONFIG_SPACE_OFFSET) as _
    }
}

bitflags! {
    /// The device status field.
    struct DeviceStatus: u32 {
        /// Indicates that the guest OS has found the device and recognized it
        /// as a valid virtio device.
        const ACKNOWLEDGE = 1;

        /// Indicates that the guest OS knows how to drive the device.
        const DRIVER = 2;

        /// Indicates that something went wrong in the guest, and it has given
        /// up on the device. This could be an internal error, or the driver
        /// didn’t like the device for some reason, or even a fatal error
        /// during device operation.
        const FAILED = 128;

        /// Indicates that the driver has acknowledged all the features it
        /// understands, and feature negotiation is complete.
        const FEATURES_OK = 8;

        /// Indicates that the driver is set up and ready to drive the device.
        const DRIVER_OK = 4;

        /// Indicates that the device has experienced an error from which it
        /// can’t recover.
        const DEVICE_NEEDS_RESET = 64;
    }
}

const CONFIG_SPACE_OFFSET: usize = 0x100;

/// Types of virtio devices.
#[repr(u8)]
#[derive(Debug, Eq, PartialEq)]
#[allow(missing_docs)]
pub enum DeviceType {
    Invalid = 0,
    Network = 1,
    Block = 2,
    Console = 3,
    EntropySource = 4,
    MemoryBallooning = 5,
    IoMemory = 6,
    Rpmsg = 7,
    ScsiHost = 8,
    _9P = 9,
    Mac80211 = 10,
    RprocSerial = 11,
    VirtioCAIF = 12,
    MemoryBalloon = 13,
    GPU = 16,
    Timer = 17,
    Input = 18,
    Socket = 19,
    Crypto = 20,
    SignalDistributionModule = 21,
    Pstore = 22,
    IOMMU = 23,
    Memory = 24,
}