Struct virtio_queue::QueueState

pub struct QueueState {
    pub max_size: u16,
    pub next_avail: Wrapping<u16>,
    pub next_used: Wrapping<u16>,
    pub event_idx_enabled: bool,
    pub num_added: Wrapping<u16>,
    pub size: u16,
    pub ready: bool,
    pub desc_table: GuestAddress,
    pub avail_ring: GuestAddress,
    pub used_ring: GuestAddress,
}

Struct to maintain information and manipulate state of a virtio queue.

WARNING: The way the QueueState is defined now, it can be used as the queue object, therefore it is allowed to set up and use an invalid queue (initialized with random data since the QueueState’s fields are public). When fixing https://github.com/rust-vmm/vm-virtio/issues/143, we plan to rename QueueState to Queue, and define a new QueueState that would be the actual state of the queue (no Wrappings in it, for example). This way, we will also be able to do the checks that we normally do in the queue’s field setters when starting from scratch, when trying to create a Queue from a QueueState.

Fields

max_size: u16

The maximum size in elements offered by the device.

next_avail: Wrapping<u16>

Tail position of the available ring.

next_used: Wrapping<u16>

Head position of the used ring.

event_idx_enabled: bool

VIRTIO_F_RING_EVENT_IDX negotiated.

num_added: Wrapping<u16>

The number of descriptor chains placed in the used ring via add_used since the last time needs_notification was called on the associated queue.

size: u16

The queue size in elements the driver selected.

ready: bool

Indicates if the queue is finished with configuration.

desc_table: GuestAddress

Guest physical address of the descriptor table.

avail_ring: GuestAddress

Guest physical address of the available ring.

used_ring: GuestAddress

Guest physical address of the used ring.

Trait Implementations

impl Debug for QueueState

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

Formats the value using the given formatter.

impl Default for QueueState

fn default() -> QueueState

Returns the “default value” for a type.

impl PartialEq<QueueState> for QueueState

fn eq(&self, other: &QueueState) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &QueueState) -> bool

This method tests for !=.

impl<'a> QueueStateGuard<'a> for QueueState

type G = &'a mut QueueState

Type for guard returned by Self::lock().

impl QueueStateOwnedT for QueueState

fn iter<M>(&mut self, mem: M) -> Result<AvailIter<'_, M>, Error> where
    M: Deref,
    M::Target: GuestMemory, 

Get a consuming iterator over all available descriptor chain heads offered by the driver.

fn go_to_previous_position(&mut self)

Undo the last advancement of the next available index field by decrementing its value by one.

impl QueueStateT for QueueState

fn new(max_size: u16) -> Self

Construct an empty virtio queue state object with the given max_size.

fn is_valid<M: GuestMemory>(&self, mem: &M) -> bool

Check whether the queue configuration is valid.

fn reset(&mut self)

Reset the queue to the initial state.

fn lock(&mut self) -> <Self as QueueStateGuard<'_>>::G

Get an exclusive reference to the underlying QueueState object.

fn max_size(&self) -> u16

Get the maximum size of the virtio queue.

fn size(&self) -> u16

Get the actual size configured by the guest.

fn set_size(&mut self, size: u16)

Configure the queue size for the virtio queue.

fn ready(&self) -> bool

Check whether the queue is ready to be processed.

fn set_ready(&mut self, ready: bool)

Configure the queue to ready for processing state.

fn set_desc_table_address(&mut self, low: Option<u32>, high: Option<u32>)

Set the descriptor table address for the queue.

fn set_avail_ring_address(&mut self, low: Option<u32>, high: Option<u32>)

Set the available ring address for the queue.

fn set_used_ring_address(&mut self, low: Option<u32>, high: Option<u32>)

Set the used ring address for the queue.

fn set_event_idx(&mut self, enabled: bool)

Enable/disable the VIRTIO_F_RING_EVENT_IDX feature for interrupt coalescing.

fn avail_idx<M>(&self, mem: &M, order: Ordering) -> Result<Wrapping<u16>, Error> where
    M: GuestMemory + ?Sized, 

Read the idx field from the available ring.

fn used_idx<M: GuestMemory>(
    &self,
    mem: &M,
    order: Ordering
) -> Result<Wrapping<u16>, Error>

Read the idx field from the used ring.

fn add_used<M: GuestMemory>(
    &mut self,
    mem: &M,
    head_index: u16,
    len: u32
) -> Result<(), Error>

Put a used descriptor head into the used ring.

fn enable_notification<M: GuestMemory>(
    &mut self,
    mem: &M
) -> Result<bool, Error>

Enable notification events from the guest driver.

fn disable_notification<M: GuestMemory>(&mut self, mem: &M) -> Result<(), Error>

Disable notification events from the guest driver.

fn needs_notification<M: GuestMemory>(&mut self, mem: &M) -> Result<bool, Error>

Check whether a notification to the guest is needed.

fn next_avail(&self) -> u16

Return the index of the next entry in the available ring.

fn set_next_avail(&mut self, next_avail: u16)

Set the index of the next entry in the available ring.

fn next_used(&self) -> u16

Return the index for the next descriptor in the used ring.

fn set_next_used(&mut self, next_used: u16)

Set the index for the next descriptor in the used ring.

fn pop_descriptor_chain<M>(&mut self, mem: M) -> Option<DescriptorChain<M>> where
    M: Clone + Deref,
    M::Target: GuestMemory, 

Pop and return the next available descriptor chain, or None when there are no more descriptor chains available.

fn lock_with_memory<M>(
    &mut self,
    mem: M
) -> QueueGuard<M, <Self as QueueStateGuard<'_>>::G> where
    M: Deref + Clone,
    M::Target: GuestMemory + Sized, 

Get an exclusive reference to the underlying QueueState object with an associated GuestMemory object.

impl StructuralPartialEq for QueueState