refactor(adapter): split trap/page_table/smp/entry by concern; trim comments

crates/hw-virtio/src/gpu.rs

@@ -75,7 +75,7 @@ pub fn resource_flush(mmio: &impl MmioAccess, queue: &VirtioQueue, dma: &GpuDmaA
 fn write_cmd_header(cmd_va: VirtualAddress, cmd_type: u32) {
     unsafe {
         let p = cmd_va.raw() as *mut u8;
-        // Use volatile writes to zero the buffer — ensures device sees the zeros
+        // Volatile so the device sees the zeros.
         for i in 0..128 {
             core::ptr::write_volatile((p as *mut u32).add(i), 0);
         }

crates/hw-virtio/src/mmio.rs

@@ -89,8 +89,7 @@ pub const MMIO_FIRST: usize = 0x10001000;
 pub const MMIO_STRIDE: usize = 0x1000;
 pub const MMIO_SLOTS: usize = 8;
 
-/// Probes the MMIO slots starting at `first`, the address the caller sees
-/// slot 0 at (`MMIO_FIRST` itself, or wherever it is mapped).
+/// Probes the MMIO slots, with slot 0 at `first` as the caller maps it.
 pub fn scan_for_device(first: usize, device_id: u32) -> Option<DirectMmio> {
     for slot in 0..MMIO_SLOTS {
         if let Some(mmio) = probe_slot(first + slot * MMIO_STRIDE, device_id) {