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[i2c] Allow zero-length requests

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Commands like SMBUS Quick don't require a buffer for the request and are
called as zero-length requests. The specification allows such requests
under the VIRTIO_I2C_F_ZERO_LENGTH_REQUEST feature, which is mandatory
to be implemented by the devices now.

Add support for zero-length requests.

Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
This commit is contained in:
Viresh Kumar 2021-10-21 12:26:55 +05:30
parent 3f53229bbb
commit fbab2abc79
3 changed files with 82 additions and 37 deletions
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2
coverage_config_x86_64.json
View File

@ -1,5 +1,5 @@
{
"coverage_score": 59.8,
"coverage_score": 58.4,
"exclude_path": "",
"crate_features": ""
}

22
src/i2c/src/i2c.rs
View File

@ -34,6 +34,8 @@ pub enum Error {
SMBusCommandInvalid(u32),
#[error("Invalid SMBus transfer, request-count: {0}, req[0].len: {1}, req[1].len: {2}")]
SMBusTransferInvalid(usize, u16, u16),
#[error("Invalid I2C transfer, request with invalid count: {0}")]
I2cTransferInvalid(usize),
#[error("Failed to open adapter at /dev/i2c-{0}")]
DeviceOpenFailed(u32),
#[error("Ioctl command failed for {0} operation: {1}")]
@ -194,7 +196,7 @@ impl SmbusMsg {
// Special Read requests
0 => Ok(SmbusMsg {
read_write,
command: reqs[0].buf[0],
command: 0,
size: I2C_SMBUS_QUICK,
data: None,
}),
@ -356,6 +358,10 @@ impl I2cDevice for PhysDevice {
let len = reqs.len();
for req in reqs {
if req.len == 0 {
return Err(Error::I2cTransferInvalid(0));
}
msgs.push(I2cMsg {
addr: req.addr,
flags: req.flags,
@ -745,7 +751,7 @@ pub mod tests {
addr: 0x3,
flags: 0,
len: 0,
buf: vec![0],
buf: Vec::<u8>::new(),
}];
i2c_map.transfer(&mut reqs).unwrap();
@ -1026,6 +1032,18 @@ pub mod tests {
Error::IoctlFailure("rdwr", IoError::last())
);
// rdwr failure - missing buffer
let mut reqs = [I2cReq {
addr: 0x4,
flags: 0,
len: 0,
buf: Vec::<u8>::new(),
}];
assert_eq!(
dev.rdwr(&mut reqs).unwrap_err(),
Error::I2cTransferInvalid(0)
);
// smbus failure
let mut data = SmbusMsg {
read_write: 0,

95
src/i2c/src/vhu_i2c.rs
View File

@ -23,6 +23,9 @@ use vmm_sys_util::eventfd::{EventFd, EFD_NONBLOCK};
use crate::i2c::*;
/// Virtio I2C Feature bits
const VIRTIO_I2C_F_ZERO_LENGTH_REQUEST: u16 = 0;
const QUEUE_SIZE: usize = 1024;
const NUM_QUEUES: usize = 1;
@ -77,6 +80,9 @@ struct VirtioI2cOutHdr {
}
unsafe impl ByteValued for VirtioI2cOutHdr {}
/// VirtioI2cOutHdr Flags
const VIRTIO_I2C_FLAGS_M_RD: u32 = 1 << 1;
#[derive(Copy, Clone, Default)]
#[repr(C)]
struct VirtioI2cInHdr {
@ -118,7 +124,7 @@ impl<D: I2cDevice> VhostUserI2cBackend<D> {
for desc_chain in requests.clone() {
let descriptors: Vec<_> = desc_chain.clone().collect();
if descriptors.len() != 3 {
if (descriptors.len() != 2) && (descriptors.len() != 3) {
return Err(Error::UnexpectedDescriptorCount);
}
@ -131,12 +137,17 @@ impl<D: I2cDevice> VhostUserI2cBackend<D> {
return Err(Error::UnexpectedDescriptorSize);
}
let desc_buf = descriptors[1];
if desc_buf.len() == 0 {
return Err(Error::UnexpectedDescriptorSize);
}
let out_hdr = desc_chain
.memory()
.read_obj::<VirtioI2cOutHdr>(desc_out_hdr.addr())
.map_err(|_| Error::DescriptorReadFailed)?;
let desc_in_hdr = descriptors[2];
let flags = match out_hdr.flags.to_native() & VIRTIO_I2C_FLAGS_M_RD {
VIRTIO_I2C_FLAGS_M_RD => I2C_M_RD,
_ => 0,
};
let desc_in_hdr = descriptors[descriptors.len() - 1];
if !desc_in_hdr.is_write_only() {
return Err(Error::UnexpectedReadableDescriptor);
}
@ -145,28 +156,40 @@ impl<D: I2cDevice> VhostUserI2cBackend<D> {
return Err(Error::UnexpectedDescriptorSize);
}
let mut buf: Vec<u8> = vec![0; desc_buf.len() as usize];
let (buf, len) = match descriptors.len() {
// Buffer is available
3 => {
let desc_buf = descriptors[1];
let len = desc_buf.len();
let mut flags: u16 = 0;
if len == 0 {
return Err(Error::UnexpectedDescriptorSize);
}
let mut buf = vec![0; len as usize];
if desc_buf.is_write_only() {
flags = I2C_M_RD;
} else {
desc_chain
.memory()
.read(&mut buf, desc_buf.addr())
.map_err(|_| Error::DescriptorReadFailed)?;
}
if flags != I2C_M_RD {
if desc_buf.is_write_only() {
return Err(Error::UnexpectedWriteOnlyDescriptor);
}
let out_hdr = desc_chain
.memory()
.read_obj::<VirtioI2cOutHdr>(desc_out_hdr.addr())
.map_err(|_| Error::DescriptorReadFailed)?;
desc_chain
.memory()
.read(&mut buf, desc_buf.addr())
.map_err(|_| Error::DescriptorReadFailed)?;
} else if !desc_buf.is_write_only() {
return Err(Error::UnexpectedReadableDescriptor);
}
(buf, len)
}
_ => (Vec::<u8>::new(), 0),
};
reqs.push(I2cReq {
addr: out_hdr.addr.to_native() >> 1,
flags,
len: desc_buf.len() as u16,
len: len as u16,
buf,
});
}
@ -182,16 +205,23 @@ impl<D: I2cDevice> VhostUserI2cBackend<D> {
for (i, desc_chain) in requests.iter().enumerate() {
let descriptors: Vec<_> = desc_chain.clone().collect();
let desc_buf = descriptors[1];
let desc_in_hdr = descriptors[2];
let desc_in_hdr = descriptors[descriptors.len() - 1];
let mut len = size_of::<VirtioI2cInHdr>() as u32;
// Write the data read from the I2C device
if desc_buf.is_write_only() {
desc_chain
.memory()
.write(&reqs[i].buf, desc_buf.addr())
.map_err(|_| Error::DescriptorWriteFailed)?;
if descriptors.len() == 3 {
let desc_buf = descriptors[1];
// Write the data read from the I2C device
if reqs[i].flags == I2C_M_RD {
desc_chain
.memory()
.write(&reqs[i].buf, desc_buf.addr())
.map_err(|_| Error::DescriptorWriteFailed)?;
}
if in_hdr.status == VIRTIO_I2C_MSG_OK {
len += desc_buf.len();
}
}
// Write the transfer status
@ -200,10 +230,6 @@ impl<D: I2cDevice> VhostUserI2cBackend<D> {
.write_obj::<VirtioI2cInHdr>(in_hdr, desc_in_hdr.addr())
.map_err(|_| Error::DescriptorWriteFailed)?;
if in_hdr.status == VIRTIO_I2C_MSG_OK {
len += desc_buf.len();
}
if vring.add_used(desc_chain.head_index(), len).is_err() {
warn!("Couldn't return used descriptors to the ring");
}
@ -235,6 +261,7 @@ impl<D: 'static + I2cDevice + Sync + Send> VhostUserBackendMut<VringRwLock, ()>
| 1 << VIRTIO_F_NOTIFY_ON_EMPTY
| 1 << VIRTIO_RING_F_INDIRECT_DESC
| 1 << VIRTIO_RING_F_EVENT_IDX
| 1 << VIRTIO_I2C_F_ZERO_LENGTH_REQUEST
| VhostUserVirtioFeatures::PROTOCOL_FEATURES.bits()
}
@ -314,7 +341,7 @@ mod tests {
assert_eq!(backend.num_queues(), NUM_QUEUES);
assert_eq!(backend.max_queue_size(), QUEUE_SIZE);
assert_eq!(backend.features(), 0x171000000);
assert_eq!(backend.features(), 0x171000001);
assert_eq!(backend.protocol_features(), VhostUserProtocolFeatures::MQ);
assert_eq!(backend.queues_per_thread(), vec![0xffff_ffff]);