vmbase: Enter clients with dynamic PTs live

The layout and linker sections of clients are controlled by a linker
script provided by vmbase so the library should know how to replicate
the client-specific static PTs to generate the dynamic PTs. Therefore,
teach vmbase to use the information it gets from the linker to replicate
the client static PTs, with client-agnostic code, and switch to the
dynamic PTs before entering its clients.

Bug: 377276983
Test: m {pvmfw,rialto,vmbase_example_{bios,kernel}}_bin
Test: atest rialto_test vmbase_example.integration_test
Change-Id: I90fa0e62e6e4cb8474f3294633cee775b1191c71
diff --git a/guest/vmbase_example/src/main.rs b/guest/vmbase_example/src/main.rs
index 138c90e..4c5e880 100644
--- a/guest/vmbase_example/src/main.rs
+++ b/guest/vmbase_example/src/main.rs
@@ -25,7 +25,6 @@
 
 use crate::layout::print_addresses;
 use crate::pci::check_pci;
-use aarch64_paging::MapError;
 use alloc::{vec, vec::Vec};
 use core::ptr::addr_of_mut;
 use cstr::cstr;
@@ -35,15 +34,9 @@
     bionic, configure_heap,
     fdt::pci::PciInfo,
     generate_image_header,
-    layout::{
-        console_uart_page, crosvm::FDT_MAX_SIZE, data_bss_range, eh_stack_range, rodata_range,
-        stack_range, text_range,
-    },
+    layout::crosvm::FDT_MAX_SIZE,
     linker, logger, main,
-    memory::{
-        deactivate_dynamic_page_tables, map_data, switch_to_dynamic_page_tables, PageTable,
-        SIZE_64KB,
-    },
+    memory::{deactivate_dynamic_page_tables, map_data, SIZE_64KB},
 };
 
 static INITIALISED_DATA: [u32; 4] = [1, 2, 3, 4];
@@ -54,17 +47,6 @@
 main!(main);
 configure_heap!(SIZE_64KB);
 
-fn init_page_table(page_table: &mut PageTable) -> Result<(), MapError> {
-    page_table.map_device(&console_uart_page().into())?;
-    page_table.map_code(&text_range().into())?;
-    page_table.map_rodata(&rodata_range().into())?;
-    page_table.map_data(&data_bss_range().into())?;
-    page_table.map_data(&eh_stack_range().into())?;
-    page_table.map_data(&stack_range().into())?;
-
-    Ok(())
-}
-
 /// Entry point for VM bootloader.
 pub fn main(arg0: u64, arg1: u64, arg2: u64, arg3: u64) {
     log::set_max_level(LevelFilter::Debug);
@@ -75,12 +57,6 @@
     check_data();
     check_stack_guard();
 
-    let mut page_table = PageTable::default();
-    init_page_table(&mut page_table).unwrap();
-    info!("Activating IdMap...");
-    switch_to_dynamic_page_tables(page_table);
-    info!("Activated.");
-
     info!("Checking FDT...");
     let fdt_addr = usize::try_from(arg0).unwrap();
     // SAFETY: The DTB range is valid, writable memory, and we don't construct any aliases to it.