perf(devices): add inline hints to hot-path helper functions

Add #[inline] attributes to small, frequently-called helper functions
in virtio device hot paths:

1. vsock_windows.rs:
   - hdr_u16/u32/u64: Read header fields (called on every packet)
   - set_u16/u32/u64: Write header fields (called on every response)

2. net_windows.rs:
   - VirtioNetHdr::from_bytes: Parse header (called on every TX frame)
   - VirtioNetHdr::to_bytes: Serialize header (called on every RX frame)

These functions are 1-3 lines and called in tight loops. Inlining
eliminates function call overhead and enables better optimization.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: hikejs

src/devices/src/virtio/net_windows.rs

@@ -73,6 +73,7 @@ struct VirtioNetHdr {
 }
 
 impl VirtioNetHdr {
+    #[inline]
     fn from_bytes(bytes: &[u8]) -> Self {
         if bytes.len() < VIRTIO_NET_HDR_SIZE {
             return Self::default();
@@ -87,6 +88,7 @@ impl VirtioNetHdr {
         }
     }
 
+    #[inline]
     fn to_bytes(&self) -> [u8; VIRTIO_NET_HDR_SIZE] {
         let mut bytes = [0u8; VIRTIO_NET_HDR_SIZE];
         bytes[0] = self.flags;

src/devices/src/virtio/vsock_windows.rs

@@ -333,26 +333,32 @@ impl Vsock {
         mem.write_slice(hdr, addr).is_ok()
     }
 
+    #[inline]
     fn hdr_u16(hdr: &[u8; 44], off: usize) -> u16 {
         byte_order::read_le_u16(&hdr[off..off + 2])
     }
 
+    #[inline]
     fn hdr_u32(hdr: &[u8; 44], off: usize) -> u32 {
         byte_order::read_le_u32(&hdr[off..off + 4])
     }
 
+    #[inline]
     fn hdr_u64(hdr: &[u8; 44], off: usize) -> u64 {
         byte_order::read_le_u64(&hdr[off..off + 8])
     }
 
+    #[inline]
     fn set_u16(hdr: &mut [u8; 44], off: usize, value: u16) {
         byte_order::write_le_u16(&mut hdr[off..off + 2], value)
     }
 
+    #[inline]
     fn set_u32(hdr: &mut [u8; 44], off: usize, value: u32) {
         byte_order::write_le_u32(&mut hdr[off..off + 4], value)
     }
 
+    #[inline]
     fn set_u64(hdr: &mut [u8; 44], off: usize, value: u64) {
         byte_order::write_le_u64(&mut hdr[off..off + 8], value)
     }