Struct GuestSharedMemory

pub struct GuestSharedMemory {
    pub lock: Arc<RwLock<()>>,
    /* private fields */
}

A GuestSharedMemory is used to represent the reference to all-of-memory that is taken by the virtual cpu. Because of the memory model limitations that affect HostSharedMemory, it is likely fairly important (to ensure that our UB remains limited to interaction with an external compilation unit that likely can’t be discovered by the compiler) that rust users do not perform racy accesses to the guest communication buffers that are also accessed by HostSharedMemory.

Fields

lock: Arc<RwLock<()>>

The lock that indicates this shared memory is being used by non-Rust code

This lock must be held whenever the guest is executing, because it prevents the host from converting its HostSharedMemory to an ExclusiveSharedMemory. Since the guest may arbitrarily mutate the shared memory, only synchronized accesses from Rust should be allowed!

We cannot enforce this in the type system, because the memory is mapped in to the VM at VM creation time.

Trait Implementations

impl Debug for GuestSharedMemory

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

Formats the value using the given formatter.

impl SharedMemory for GuestSharedMemory

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 GuestSharedMemory