Struct ExclusiveSharedMemory

pub struct ExclusiveSharedMemory { /* private fields */ }

These three structures represent various phases of the lifecycle of a memory buffer that is shared with the guest. An ExclusiveSharedMemory is used for certain operations that unrestrictedly write to the shared memory, including setting it up and taking snapshots.

Implementations

impl ExclusiveSharedMemory

pub fn new(min_size_bytes: usize) -> Result<Self>

Create a new region of shared memory with the given minimum size in bytes. The region will be surrounded by guard pages.

Return Err if shared memory could not be allocated.

pub fn as_slice<'a>(&'a self) -> &'a [u8]

Internal helper method to get the backing memory as a slice.

Safety

See the discussion on as_mut_slice, with the third point replaced by:

• The memory referenced by the returned slice must not be mutated for the duration of lifetime ’a, except inside an UnsafeCell.

  Host accesses from Safe Rust necessarily follow this rule, because the returned slice’s lifetime is the same as that of a borrow of self, preventing mutations via other methods.

pub fn copy_from_slice(&mut self, src: &[u8], offset: usize) -> Result<()>

Copies all bytes from src to self starting at offset

pub fn build(self) -> (HostSharedMemory, GuestSharedMemory)

Convert the ExclusiveSharedMemory, which may be freely modified, into a GuestSharedMemory, which may be somewhat freely modified (mostly by the guest), and a HostSharedMemory, which may only make certain kinds of accesses that do not race in the presence of malicious code inside the guest mutating the GuestSharedMemory.

Trait Implementations

impl Debug for ExclusiveSharedMemory

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl SharedMemory for ExclusiveSharedMemory

fn region(&self) -> &HostMapping

Return a readonly reference to the host mapping backing this SharedMemory

fn with_exclusivity<T, F: FnOnce(&mut ExclusiveSharedMemory) -> T>( &mut self, f: F, ) -> Result<T>

Run some code with exclusive access to the SharedMemory underlying this. If the SharedMemory is not an ExclusiveSharedMemory, any concurrent accesses to the relevant HostSharedMemory/GuestSharedMemory may make this fail, or be made to fail by this, and should be avoided.

fn base_addr(&self) -> usize

Return the base address of the host mapping of this region. Following the general Rust philosophy, this does not need to be marked as unsafe because doing anything with this pointer itself requires unsafe.

fn base_ptr(&self) -> *mut u8

Return the base address of the host mapping of this region as a pointer. Following the general Rust philosophy, this does not need to be marked as unsafe because doing anything with this pointer itself requires unsafe.

fn mem_size(&self) -> usize

Return the length of usable memory contained in self. The returned size does not include the size of the surrounding guard pages.

fn raw_ptr(&self) -> *mut u8

Return the raw base address of the host mapping, including the guard pages.

fn raw_mem_size(&self) -> usize

Return the raw size of the host mapping, including the guard pages.

impl Send for ExclusiveSharedMemory