fix: use correct ioctl wrapper for create_device

Use `ioctl_with_mut_ref` instead of `ioctl_with_ref`
in the `create_device` method as it needs to write to the
`kvm_create_device` struct passed to it. This incorrect
usage of `ioctl_with_ref` causes newer versions of Rust compiler
(1.82 and above) to treat the `kvm_create_device` struct as read-only
and bypass following reads from it. This optimization lead to incorrect
value being passed to the `File::from_raw_fd` call.

Signed-off-by: Egor Lazarchuk <yegorlz@amazon.co.uk>

CHANGELOG.md

@@ -2,6 +2,12 @@
 
 ## Upcoming Release
 
+### Fixed
+
+- [[#298](https://github.com/rust-vmm/kvm/pull/298)]: Fixed incorrect usage of `ioctl_wit_ref` in the
+  `create_device` method. Replace it with `ioctl_wit_mut_ref` as the passed parameter may be mutated by the
+  ioctl.
+
 ## v0.19.0
 
 ### Added

src/ioctls/vm.rs

@@ -22,11 +22,11 @@ use crate::ioctls::{KvmRunWrapper, Result};
 use crate::kvm_ioctls::*;
 use vmm_sys_util::errno;
 use vmm_sys_util::eventfd::EventFd;
+#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
+use vmm_sys_util::ioctl::ioctl;
 #[cfg(target_arch = "x86_64")]
 use vmm_sys_util::ioctl::ioctl_with_mut_ptr;
-#[cfg(any(target_arch = "x86_64", target_arch = "aarch64"))]
-use vmm_sys_util::ioctl::{ioctl, ioctl_with_mut_ref};
-use vmm_sys_util::ioctl::{ioctl_with_ref, ioctl_with_val};
+use vmm_sys_util::ioctl::{ioctl_with_mut_ref, ioctl_with_ref, ioctl_with_val};
 
 /// An address either in programmable I/O space or in memory mapped I/O space.
 ///
@@ -1306,7 +1306,7 @@ impl VmFd {
     /// ```
     pub fn create_device(&self, device: &mut kvm_create_device) -> Result<DeviceFd> {
         // SAFETY: Safe because we are calling this with the VM fd and we trust the kernel.
-        let ret = unsafe { ioctl_with_ref(self, KVM_CREATE_DEVICE(), device) };
+        let ret = unsafe { ioctl_with_mut_ref(self, KVM_CREATE_DEVICE(), device) };
         if ret == 0 {
             // SAFETY: We validated the return of the function creating the fd and we trust the
             // kernel.