main: Split boot off device into own function

Also remove the behaviour of resetting on failure, instead return true
on boot success or false otherwise. When we start to look at iterating
over multiple devices returning false will cause the firmwarware to try
another device.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>

Author: rbradford

src/main.rs

@@ -25,8 +25,6 @@ mod common;
 
 use core::panic::PanicInfo;
 
-use cpuio::Port;
-
 mod block;
 mod bzimage;
 mod efi;
@@ -46,19 +44,6 @@ fn panic(_info: &PanicInfo) -> ! {
     loop {}
 }
 
-#[cfg(not(test))]
-/// Reset the VM via the keyboard controller
-fn i8042_reset() -> ! {
-    loop {
-        let mut good: u8 = 0x02;
-        let mut i8042_command: Port<u8> = unsafe { Port::new(0x64) };
-        while good & 0x02 > 0 {
-            good = i8042_command.read();
-        }
-        i8042_command.write(0xFE);
-    }
-}
-
 #[cfg(not(test))]
 /// Enable SSE2 for XMM registers (needed for EFI calling)
 fn enable_sse2() {
@@ -95,37 +80,11 @@ const VIRTIO_PCI_VENDOR_ID: u16 = 0x1af4;
 const VIRTIO_PCI_BLOCK_DEVICE_ID: u16 = 0x1042;
 
 #[cfg(not(test))]
-#[allow(unused_attributes)]
-#[no_mangle]
-pub extern "C" fn _start() -> ! {
-    unsafe {
-        asm!("movq $$0x180000, %rsp");
-    }
-
-    log!("Starting..\n");
-
-    enable_sse2();
-    setup_pagetables();
-
-    pci::print_bus();
-
-    let mut pci_transport;
-    let mut mmio_transport;
-
-    let mut device = if let Some(pci_device) =
-        pci::search_bus(VIRTIO_PCI_VENDOR_ID, VIRTIO_PCI_BLOCK_DEVICE_ID)
-    {
-        pci_transport = pci::VirtioPciTransport::new(pci_device);
-        block::VirtioBlockDevice::new(&mut pci_transport)
-    } else {
-        mmio_transport = mmio::VirtioMMIOTransport::new(0xd000_0000u64);
-        block::VirtioBlockDevice::new(&mut mmio_transport)
-    };
-
+fn boot_from_device(device: &mut block::VirtioBlockDevice) -> bool {
     match device.init() {
         Err(_) => {
             log!("Error configuring block device\n");
-            i8042_reset();
+            return false;
         }
         Ok(_) => log!(
             "Virtio block device configured. Capacity: {} sectors\n",
@@ -135,18 +94,18 @@ pub extern "C" fn _start() -> ! {
 
     let mut f;
 
-    match part::find_efi_partition(&device) {
+    match part::find_efi_partition(device) {
         Ok((start, end)) => {
             log!("Found EFI partition\n");
-            f = fat::Filesystem::new(&device, start, end);
+            f = fat::Filesystem::new(device, start, end);
             if f.init().is_err() {
                 log!("Failed to create filesystem\n");
-                i8042_reset();
+                return false;
             }
         }
         Err(_) => {
             log!("Failed to find EFI partition\n");
-            i8042_reset();
+            return false;
         }
     }
 
@@ -159,26 +118,31 @@ pub extern "C" fn _start() -> ! {
             jump_address = addr;
         }
         Err(_) => {
-            log!("Error loading default entry\n");
+            log!("Error loading default entry. Using EFI boot.\n");
             match f.open("/EFI/BOOT/BOOTX64 EFI") {
                 Ok(mut file) => {
                     log!("Found bootloader (BOOTX64.EFI)\n");
                     let mut l = pe::Loader::new(&mut file);
                     match l.load(0x20_0000) {
                         Ok((a, size)) => {
                             log!("Executable loaded\n");
-                            efi::efi_exec(a, 0x20_0000, size, &f, &device);
-                            i8042_reset();
+                            efi::efi_exec(a, 0x20_0000, size, &f, device);
+                            return true;
+                        }
+                        Err(e) => {
+                            match e {
+                                pe::Error::FileError => log!("File error\n"),
+                                pe::Error::InvalidExecutable => log!("Invalid executable\n"),
+                            }
+                            return false;
                         }
-                        Err(e) => match e {
-                            pe::Error::FileError => log!("File error\n"),
-                            pe::Error::InvalidExecutable => log!("Invalid executable\n"),
-                        },
                     }
                 }
-                Err(_) => log!("Failed to find bootloader\n"),
+                Err(_) => {
+                    log!("Failed to find bootloader\n");
+                    return false;
+                }
             }
-            i8042_reset();
         }
     }
 
@@ -190,6 +154,39 @@ pub extern "C" fn _start() -> ! {
     let ptr = jump_address as *const ();
     let code: extern "C" fn(u64, u64) = unsafe { core::mem::transmute(ptr) };
     (code)(0 /* dummy value */, bzimage::ZERO_PAGE_START as u64);
+    true
+}
 
-    i8042_reset()
+#[cfg(not(test))]
+#[allow(unused_attributes)]
+#[no_mangle]
+pub extern "C" fn _start() -> ! {
+    unsafe {
+        asm!("movq $$0x180000, %rsp");
+    }
+
+    log!("Starting..\n");
+
+    enable_sse2();
+    setup_pagetables();
+
+    pci::print_bus();
+
+    let mut pci_transport;
+    let mut mmio_transport;
+
+    let mut device = if let Some(pci_device) =
+        pci::search_bus(VIRTIO_PCI_VENDOR_ID, VIRTIO_PCI_BLOCK_DEVICE_ID)
+    {
+        pci_transport = pci::VirtioPciTransport::new(pci_device);
+        block::VirtioBlockDevice::new(&mut pci_transport)
+    } else {
+        mmio_transport = mmio::VirtioMMIOTransport::new(0xd000_0000u64);
+        block::VirtioBlockDevice::new(&mut mmio_transport)
+    };
+
+    boot_from_device(&mut device);
+
+    #[allow(clippy::empty_loop)]
+    loop {}
 }