Store VCPU in percore variable

Author: ALSchwalm

mythril/src/kmain.rs

@@ -126,7 +126,7 @@ fn build_vm(
     .unwrap();
 
     virtual_devices.push(RwLock::new(virtdev::DynamicVirtualDevice::Qemu(
-        fw_cfg_builder.build(),
+        fw_cfg_builder.build().expect("Failed to build FW Cfg"),
     )));
 
     vm::VirtualMachine::new(vm_id, config, info).expect("Failed to create vm")

mythril/src/vcpu.rs

@@ -26,8 +26,12 @@ extern "C" {
 const PER_CORE_HOST_STACK_SIZE: usize = 1024 * 1024;
 
 declare_per_core! {
+    // NOTE: The per-core stack cannot be part of the VCpu type because an
+    // instance of VCpu will (briefly) reside _on_ the stack
     static mut HOST_STACK: [u8; PER_CORE_HOST_STACK_SIZE]
         = [0u8; PER_CORE_HOST_STACK_SIZE];
+
+    static mut VCPU: Option<VCpu> = None;
 }
 
 /// The post-startup point where a core begins executing its statically
@@ -47,7 +51,7 @@ pub fn mp_entry_point() -> ! {
         vm
     };
 
-    let mut vcpu = VCpu::new(vm).expect("Failed to create vcpu");
+    let vcpu = VCpu::new(vm).expect("Failed to create vcpu");
 
     let vm_id = vm.id;
     let is_vm_bsp = vm.bsp_id() == core_id;
@@ -108,17 +112,23 @@ impl VCpu {
     /// Note that the result must be `Pin`, as the `VCpu` pushes its own
     /// address on to the per-core host stack so it can be retrieved on
     /// VMEXIT.
-    pub fn new(vm: &'static VirtualMachine) -> Result<Pin<Box<Self>>> {
+    pub fn new(vm: &'static VirtualMachine) -> Result<&'static mut Self> {
         let vmx = vmx::Vmx::enable()?;
         let vmcs = vmcs::Vmcs::new()?.activate(vmx)?;
 
-        let mut vcpu = Box::pin(Self {
+        let vcpu = Self {
             vm: vm,
             vmcs: vmcs,
             local_apic: virtdev::lapic::LocalApic::new(),
             stack: get_per_core_mut!(HOST_STACK),
             pending_interrupts: BTreeMap::new(),
-        });
+        };
+
+        unsafe {
+            // Move the VCpu off the stack to the final static location
+            *get_per_core_mut!(VCPU) = Some(vcpu);
+        }
+        let vcpu = get_per_core_mut!(VCPU).as_mut().unwrap();
 
         // All VCpus in a VM must share the same address space
         let eptp = vcpu.vm.guest_space.eptp();
@@ -136,13 +146,13 @@ impl VCpu {
             - mem::size_of::<*const Self>() as u64;
 
         // 'push' the address of this VCpu to the host stack for the vmexit
-        let raw_vcpu: *mut Self = (&mut *vcpu) as *mut Self;
+        let raw_vcpu = vcpu as *mut Self;
         unsafe {
             core::ptr::write(stack_base as *mut *mut Self, raw_vcpu);
         }
 
         Self::initialize_host_vmcs(&mut vcpu.vmcs, stack_base)?;
-        Self::initialize_guest_vmcs(&mut vcpu)?;
+        Self::initialize_guest_vmcs(vcpu)?;
         Self::initialize_ctrl_vmcs(&mut vcpu.vmcs)?;
 
         Ok(vcpu)
@@ -157,7 +167,7 @@ impl VCpu {
     }
 
     /// Begin execution in the guest context for this core
-    pub fn launch(self: Pin<Box<Self>>) -> Result<!> {
+    pub fn launch(&mut self) -> Result<!> {
         let rflags = unsafe { vmlaunch_wrapper() };
         error::check_vm_insruction(rflags, "Failed to launch vm".into())?;
 

mythril/src/virtdev/dma.rs

@@ -2,14 +2,13 @@ use crate::error::Result;
 use crate::memory::GuestPhysAddr;
 use crate::virtdev::{DeviceRegion, EmulatedDevice, Event};
 use alloc::vec::Vec;
-use spin::RwLock;
 
 #[derive(Default)]
 pub struct IoApic;
 
 impl IoApic {
-    pub fn new() -> Result<RwLock<Self>> {
-        Ok(RwLock::new(IoApic {}))
+    pub fn new() -> Result<Self> {
+        Ok(IoApic {})
     }
 }
 

mythril/src/virtdev/ignore.rs

@@ -1,7 +1,6 @@
 use crate::error::Result;
 use crate::virtdev::{DeviceEvent, DeviceRegion, EmulatedDevice, Event, Port};
 use alloc::vec::Vec;
-use spin::RwLock;
 
 #[derive(Default, Debug)]
 pub struct Keyboard8042;
@@ -10,8 +9,8 @@ impl Keyboard8042 {
     const PS2_DATA: Port = 0x0060;
     const PS2_STATUS: Port = 0x0064;
 
-    pub fn new() -> Result<RwLock<Self>> {
-        Ok(RwLock::new(Self::default()))
+    pub fn new() -> Result<Self> {
+        Ok(Self::default())
     }
 }
 

mythril/src/virtdev/ioapic.rs

@@ -12,15 +12,12 @@ use spin::RwLock;
 pub mod acpi;
 pub mod com;
 pub mod debug;
-pub mod dma;
-pub mod ignore;
 pub mod ioapic;
 pub mod keyboard;
 pub mod lapic;
 pub mod pci;
 pub mod pic;
 pub mod pit;
-pub mod pos;
 pub mod qemu_fw_cfg;
 pub mod rtc;
 pub mod vga;

mythril/src/virtdev/keyboard.rs

@@ -4,7 +4,6 @@ use alloc::collections::btree_map::BTreeMap;
 use alloc::vec::Vec;
 use core::convert::TryInto;
 use num_enum::TryFromPrimitive;
-use spin::RwLock;
 use ux;
 
 #[derive(Clone, Copy, Debug, TryFromPrimitive)]
@@ -153,7 +152,7 @@ impl PciRootComplex {
     const PCI_CONFIG_DATA: Port = 0xcfc;
     const PCI_CONFIG_DATA_MAX: Port = Self::PCI_CONFIG_DATA + 3;
 
-    pub fn new() -> Result<RwLock<Self>> {
+    pub fn new() -> Result<Self> {
         let mut devices = BTreeMap::new();
 
         let host_bridge = PciDevice {
@@ -180,10 +179,10 @@ impl PciRootComplex {
         };
         devices.insert(ich9.bdf.into(), ich9);
 
-        Ok(RwLock::new(Self {
+        Ok(Self {
             current_address: 0,
             devices: devices,
-        }))
+        })
     }
 }
 
@@ -274,7 +273,7 @@ mod test {
         GuestAddressSpaceView::new(GuestPhysAddr::new(0), space)
     }
 
-    fn complex_ready_for_reg_read(reg: u8) -> RwLock<PciRootComplex> {
+    fn complex_ready_for_reg_read(reg: u8) -> PciRootComplex {
         let view = define_test_view();
         let complex = PciRootComplex::new().unwrap();
         let addr = ((reg << 2) as u32).to_be_bytes();
@@ -286,10 +285,7 @@ mod test {
             &mut responses,
         )
         .unwrap();
-        {
-            let mut complex = complex.write();
-            complex.on_event(event).unwrap();
-        }
+        complex.on_event(event).unwrap();
         complex
     }
 

mythril/src/virtdev/mod.rs

@@ -2,7 +2,6 @@ use crate::error::Result;
 use crate::virtdev::{DeviceEvent, DeviceRegion, EmulatedDevice, Event, Port};
 use alloc::vec::Vec;
 use core::convert::TryInto;
-use spin::RwLock;
 
 #[derive(Default, Debug)]
 pub struct PicState {
@@ -23,8 +22,8 @@ impl Pic8259 {
     const PIC_ECLR_COMMAND: Port = 0x4d0;
     const PIC_ECLR_DATA: Port = Self::PIC_ECLR_COMMAND + 1;
 
-    pub fn new() -> Result<RwLock<Self>> {
-        Ok(RwLock::new(Pic8259::default()))
+    pub fn new() -> Result<Self> {
+        Ok(Pic8259::default())
     }
 }
 

mythril/src/virtdev/pci.rs

@@ -9,7 +9,6 @@ use crate::virtdev::{
 
 use alloc::vec::Vec;
 use core::convert::TryFrom;
-use spin::RwLock;
 
 #[derive(Debug)]
 enum OperatingModeState {
@@ -60,8 +59,8 @@ pub struct Pit8254 {
 }
 
 impl Pit8254 {
-    pub fn new() -> Result<RwLock<Self>> {
-        Ok(RwLock::new(Pit8254::default()))
+    pub fn new() -> Result<Self> {
+        Ok(Pit8254::default())
     }
 
     fn on_port_read(