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https://github.com/cloud-hypervisor/cloud-hypervisor.git
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55 lines
1.7 KiB
Rust
55 lines
1.7 KiB
Rust
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// Copyright © 2019 Intel Corporation
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//
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// SPDX-License-Identifier: Apache-2.0 OR BSD-3-Clause
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//
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//#![deny(missing_docs)]
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//! Virtual Function I/O (VFIO) API
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extern crate byteorder;
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extern crate kvm_bindings;
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extern crate kvm_ioctls;
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extern crate log;
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extern crate vfio_bindings;
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extern crate vm_memory;
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#[macro_use]
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extern crate vmm_sys_util;
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mod vfio_device;
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mod vfio_ioctls;
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use std::mem::size_of;
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pub use vfio_device::{VfioDevice, VfioError};
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// Returns a `Vec<T>` with a size in bytes at least as large as `size_in_bytes`.
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fn vec_with_size_in_bytes<T: Default>(size_in_bytes: usize) -> Vec<T> {
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let rounded_size = (size_in_bytes + size_of::<T>() - 1) / size_of::<T>();
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let mut v = Vec::with_capacity(rounded_size);
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for _ in 0..rounded_size {
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v.push(T::default())
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}
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v
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}
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// The kvm API has many structs that resemble the following `Foo` structure:
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//
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// ```
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// #[repr(C)]
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// struct Foo {
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// some_data: u32
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// entries: __IncompleteArrayField<__u32>,
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// }
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// ```
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//
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// In order to allocate such a structure, `size_of::<Foo>()` would be too small because it would not
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// include any space for `entries`. To make the allocation large enough while still being aligned
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// for `Foo`, a `Vec<Foo>` is created. Only the first element of `Vec<Foo>` would actually be used
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// as a `Foo`. The remaining memory in the `Vec<Foo>` is for `entries`, which must be contiguous
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// with `Foo`. This function is used to make the `Vec<Foo>` with enough space for `count` entries.
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pub fn vec_with_array_field<T: Default, F>(count: usize) -> Vec<T> {
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let element_space = count * size_of::<F>();
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let vec_size_bytes = size_of::<T>() + element_space;
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vec_with_size_in_bytes(vec_size_bytes)
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}
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