Implement vsock driver

kernel/comps/virtio/src/device/socket/config.rs

@@ -0,0 +1,44 @@
+use aster_frame::io_mem::IoMem;
+use pod::Pod;
+use aster_util::{safe_ptr::SafePtr};
+use bitflags::bitflags;
+
+use crate::transport::{self, VirtioTransport};
+
+bitflags!{
+    /// Vsock feature bits since v1.2
+    /// If no feature bit is set, only stream socket type is supported. 
+    /// If VIRTIO_VSOCK_F_SEQPACKET has been negotiated, the device MAY act as if VIRTIO_VSOCK_F_STREAM has also been negotiated.
+    pub struct VsockFeatures: u64 {
+        const VIRTIO_VSOCK_F_STREAM = 1 << 0; // stream socket type is supported.
+        const VIRTIO_VSOCK_F_SEQPACKET = 1 << 1; //seqpacket socket type is supported.
+    }
+}
+
+impl VsockFeatures {
+    pub fn support_features() -> Self {
+        VsockFeatures::VIRTIO_VSOCK_F_STREAM
+    }
+}
+
+#[derive(Debug, Clone, Copy, Pod)]
+#[repr(C)]
+pub struct VirtioVsockConfig{
+    /// The guest_cid field contains the guest’s context ID, which uniquely identifies
+    /// the device for its lifetime. The upper 32 bits of the CID are reserved and zeroed.
+    ///
+    /// According to virtio spec v1.1 2.4.1 Driver Requirements: Device Configuration Space,
+    /// drivers MUST NOT assume reads from fields greater than 32 bits wide are atomic.
+    /// So we need to split the u64 guest_cid into two parts.
+    // read only
+    pub guest_cid_low: u32,
+    // read only
+    pub guest_cid_high: u32,
+}
+
+impl VirtioVsockConfig {
+    pub(crate) fn new(transport: &dyn VirtioTransport) -> SafePtr<Self, IoMem> {
+        let memory = transport.device_config_memory();
+        SafePtr::new(memory, 0)
+    }
+}