Struct GuestMemWriter 

pub struct GuestMemWriter { /* private fields */ }

Raw pointer wrapper for guest physical memory access.

Backed by the VM-lifetime mmap of guest RAM. Device-owned descriptor buffers are exclusive to the device per the VirtIO spec — the guest will not touch them until the used ring advances.

All public methods accept guest physical addresses (GPAs) and translate them to slice offsets by subtracting gpa_base.

Implementations

impl GuestMemWriter

pub unsafe fn new(ptr: *mut u8, len: usize, gpa_base: usize) -> GuestMemWriter

Creates a new writer from the DeviceManager’s guest memory.

ptr must point to the host mapping of guest RAM, which starts at GPA gpa_base. len is the size of that mapping in bytes.

Safety

ptr must be valid for len bytes for the lifetime of the VM.

pub fn gpa_to_offset(&self, gpa: usize, access_len: usize) -> Option<usize>

Translates a GPA to a host pointer offset, returning None if the GPA falls below gpa_base (invalid) or the range exceeds the mapped region.

pub unsafe fn slice_mut(&self, gpa: usize, len: usize) -> Option<&mut [u8]>

Returns a mutable slice into guest memory at the given GPA range.

Safety

Caller must ensure no other reference (mutable or shared) to the same GPA range exists for the lifetime of the returned slice. In practice, VirtIO descriptor ownership guarantees this — each descriptor buffer is exclusive to the device that owns it.

pub fn slice(&self, gpa: usize, len: usize) -> Option<&[u8]>

Returns an immutable slice into guest memory at the given GPA range.

pub fn read_u16(&self, gpa: usize) -> u16

Reads a little-endian u16 from the given GPA. Returns 0 on out-of-bounds access.

pub fn write_u16(&self, gpa: usize, val: u16)

Writes a little-endian u16 to the given GPA. No-op on out-of-bounds access.

pub fn write_u32(&self, gpa: usize, val: u32)

Writes a little-endian u32 to the given GPA. No-op on out-of-bounds access.

pub fn write_byte(&self, gpa: usize, val: u8)

Writes a single byte to the given GPA. No-op on out-of-bounds access.

pub fn ptr(&self) -> *mut u8

Returns the raw pointer to the start of guest memory.

pub fn len(&self) -> usize

Returns the total length (in bytes) of the guest memory region.

pub fn is_empty(&self) -> bool

Returns true if the guest memory region has zero length.

pub fn gpa_base(&self) -> usize

Returns the GPA base address of the guest memory region.

Trait Implementations

impl Send for GuestMemWriter

impl Sync for GuestMemWriter