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vmm: device_manager: Use externally-supplied iommufd FD

Browse Source 
Signed-off-by: Bo Chen <bchen@crusoe.ai>
Assisted-by: Claude:Opus-4.7
This commit is contained in:
Bo Chen
2026-05-08 00:40:08 +00:00
committed by Rob Bradford
parent 867b5796a5
commit 19fb12c28b
1 changed files with 57 additions and 14 deletions
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71
vmm/src/device_manager.rs
View File

@@ -3892,7 +3892,7 @@ impl DeviceManager {
.try_clone()
.map_err(DeviceManagerError::VfioCreate)?;
let iommufd = self
let iommufd_on = self
.config
.lock()
.unwrap()
@@ -3900,11 +3900,40 @@ impl DeviceManager {
.as_ref()
.is_some_and(|p| p.iommufd);
if iommufd {
if iommufd_on {
#[cfg(feature = "kvm")]
{
info!("Using vfio cdev mode with iommufd.");
let iommufd = IommuFd::new().map_err(DeviceManagerError::IommufdCreate)?;
let iommufd_fd = self
.config
.lock()
.unwrap()
.platform
.as_ref()
.and_then(|p| p.iommufd_fd);
let iommufd = match iommufd_fd {
Some(fd) => {
info!("Using vfio cdev mode with externally-supplied iommufd fd: {fd}.");
// Dup so the IommuFd owns its own File; the
// caller-supplied fd is kept alive across reboot
// via VmConfig::preserved_fds.
// SAFETY: FFI call to dup. Trivially safe.
let dup_fd = unsafe { libc::dup(fd) };
if dup_fd < 0 {
return Err(DeviceManagerError::VfioDupFd(io::Error::last_os_error()));
}
// SAFETY: dup_fd is valid and can be owned by this File
let file = unsafe { File::from_raw_fd(dup_fd) };
// SAFETY: fd is a valid open iommufd
unsafe {
self.config.lock().unwrap().add_preserved_fds(vec![fd]);
}
IommuFd::new_from_fd(file)
}
None => {
info!("Using vfio cdev mode with iommufd.");
IommuFd::new().map_err(DeviceManagerError::IommufdCreate)?
}
};
let vfio_iommufd = VfioIommufd::new(Arc::new(iommufd), None, Some(Arc::new(dup)))
.map_err(DeviceManagerError::VfioCreate)?;
Ok(Arc::new(vfio_iommufd))
@@ -3933,15 +3962,26 @@ impl DeviceManager {
fd: i32,
vfio_ops: Arc<dyn VfioOps>,
) -> DeviceManagerResult<(VfioDevice, PathBuf)> {
assert!(
self.config
.lock()
.unwrap()
.platform
let already_bound = {
let config = self.config.lock().unwrap();
assert!(
config.platform.as_ref().is_some_and(|p| p.iommufd),
"DeviceConfig::validate enforces iommufd when fd is set",
);
assert!(
config
.platform
.as_ref()
.is_some_and(|p| p.iommufd_fd.is_some()),
"DeviceConfig::validate enforces iommufd_fd when device fd is set",
);
// If a cdev fd was preserved on a prior boot, it is already bound
// to an iommufd instance
config
.preserved_fds
.as_ref()
.is_some_and(|p| p.iommufd),
"DeviceConfig::validate enforces iommufd when fd is set",
);
.is_some_and(|s| s.contains(&fd))
};
// SAFETY: FFI call to dup. Trivially safe.
let dup_fd = unsafe { libc::dup(fd) };
@@ -3950,8 +3990,11 @@ impl DeviceManager {
}
// SAFETY: dup_fd is a freshly-opened fd owned by this File.
let file = unsafe { File::from_raw_fd(dup_fd) };
let vfio_device =
VfioDevice::new_from_fd(file, vfio_ops).map_err(DeviceManagerError::VfioCreate)?;
let vfio_device = if already_bound {
VfioDevice::new_from_bound_fd(file, vfio_ops).map_err(DeviceManagerError::VfioCreate)?
} else {
VfioDevice::new_from_fd(file, vfio_ops).map_err(DeviceManagerError::VfioCreate)?
};
// SAFETY: fd is a valid open vfio cdev FD; the VfioDevice only
// holds a dup, so VmConfig can safely take ownership of the