aarch64: fix get time runtime service failure

When enable efi_rtc inside guest kernel, a warning occurs:

[    0.764401] [Firmware Bug]: Unable to handle paging request in EFI runtime service
[    0.770671] ------------[ cut here ]------------
[    0.772014] WARNING: CPU: 0 PID: 1 at drivers/firmware/efi/runtime-wrappers.c:262 virt_efi_get_time+0x12c/0x17c

It derives from that there is lack of memory map descriptor for IO address
of RTC_PL031 passed to kernel. Allocate IO Map for it before execute
kernel/bootloader can avoid this failure and then we can get the right
time inside guest.

Fixes: #289
Signed-off-by: Jianyong Wu <[email protected]>

src/efi/mod.rs

@@ -1181,6 +1181,19 @@ pub fn efi_exec(
 
     let wrapped_fs = file::FileSystemWrapper::new(fs, efi_part_id);
 
+    // allocate descriptor for RTC on aarch64
+    #[cfg(target_arch = "aarch64")]
+    if Status::SUCCESS
+        != ALLOCATOR.borrow_mut().add_initial_allocation(
+            efi::MEMORY_MAPPED_IO,
+            1,
+            crate::arch::aarch64::layout::map::mmio::PL031_START as u64,
+            r_efi::efi::MEMORY_RUNTIME,
+        )
+    {
+        log!("Failed to allocate memory map descriptor for RTC PL031\n");
+    }
+
     let image = new_image_handle(
         crate::efi::EFI_BOOT_PATH,
         0 as Handle,