Merge pull request #114 from mythril-hypervisor/avoid-allocation

Avoid many instances of dynamic allocation

Author: ALSchwalm

mythril/Cargo.lock

@@ -12,7 +12,6 @@ test = []
 
 [dependencies]
 arraydeque = { version = "0.4.5", default-features = false }
-arrayvec = { version = "0.5.1", default-features = false }
 bitflags = "1.2.0"
 byteorder = { version = "1", default-features = false }
 num_enum = { version = "0.5.0", default-features = false }
@@ -21,6 +20,7 @@ linked_list_allocator = "0.8.6"
 log = { version = "0.4.8", default-features = false }
 multiboot = "0.3.0"
 multiboot2 = "0.9.0"
+paste = "1.0"
 raw-cpuid = "8.1.1"
 rlibc = "1.0.0"
 serde = {version = "^1", default-features = false, features = ["alloc", "derive"] }
@@ -29,6 +29,11 @@ spin = "0.5"
 ux = { version = "0.1.3", default-features = false }
 managed = { version = "0.8.0", features = ["map", "alloc"], default-features = false }
 
+[dependencies.arrayvec]
+version = "0.5.2"
+default-features = false
+features = ["unstable-const-fn"]
+
 [dependencies.iced-x86]
 version = "1.8.0"
 default-features = false

mythril/Cargo.toml

@@ -1,6 +1,6 @@
 %include "paging.mac"
 
-%define BSP_STACK_SIZE (PAGE_SIZE*50)
+%define BSP_STACK_SIZE (PAGE_SIZE*100)
 %define PAGE_HIERARCHY_SIZE (PAGE_SIZE*7)
 
 global PAGE_HIERARCHY

mythril/src/boot.S

@@ -23,6 +23,8 @@ pub fn emulate_cpuid(
 
         // Hide TSC deadline timer
         res.ecx &= !(1 << 24);
+    } else if guest_cpu.rax as u32 == 0x0b {
+        res.edx = crate::percore::read_core_id().raw as u32;
     }
 
     guest_cpu.rax = res.eax as u64 | (guest_cpu.rax & 0xffffffff00000000);

mythril/src/emulate/cpuid.rs

@@ -523,8 +523,7 @@ pub fn handle_apic_access(
             _ => return Err(Error::NotSupported),
         };
 
-        vcpu.local_apic
-            .register_write(vcpu.vm.clone(), offset, value)
+        vcpu.local_apic.register_write(vcpu.vm, offset, value)
     }
 
     let addr = vm::GUEST_LOCAL_APIC_ADDR

mythril/src/emulate/memio.rs

@@ -18,7 +18,6 @@ use crate::virtdev;
 use crate::vm;
 
 use alloc::collections::BTreeMap;
-use alloc::sync::Arc;
 use alloc::vec::Vec;
 use log::{debug, info};
 use managed::ManagedMap;
@@ -40,11 +39,11 @@ fn build_vm(
     cfg: &config::UserVmConfig,
     info: &BootInfo,
     add_uart: bool,
-) -> Arc<vm::VirtualMachine> {
+) -> vm::VirtualMachine {
     let physical_config = if add_uart == false {
-        vm::PhysicalDeviceConfig::default()
+        vm::HostPhysicalDevices::default()
     } else {
-        vm::PhysicalDeviceConfig {
+        vm::HostPhysicalDevices {
             serial: RwLock::new(Some(
                 physdev::com::Uart8250::new(0x3f8)
                     .expect("Failed to create UART"),
@@ -83,47 +82,18 @@ fn build_vm(
 
     acpi.add_sdt(madt).unwrap();
 
-    let device_map = config.virtual_devices_mut();
+    let virtual_devices = &mut config.virtual_devices;
 
-    device_map
-        .register_device(virtdev::acpi::AcpiRuntime::new(0x600).unwrap())
-        .unwrap();
-    device_map
-        .register_device(virtdev::debug::DebugPort::new(0x402))
-        .unwrap();
-    device_map
-        .register_device(virtdev::com::Uart8250::new(0x3F8))
-        .unwrap();
-    device_map
-        .register_device(virtdev::vga::VgaController::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::dma::Dma8237::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::ignore::IgnoredDevice::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::pci::PciRootComplex::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::pic::Pic8259::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::keyboard::Keyboard8042::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::pit::Pit8254::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::pos::ProgrammableOptionSelect::new())
-        .unwrap();
-    device_map
-        .register_device(virtdev::rtc::CmosRtc::new(cfg.memory))
-        .unwrap();
-    device_map
-        .register_device(virtdev::ioapic::IoApic::new())
-        .unwrap();
+    virtual_devices.push(RwLock::new(
+        virtdev::DynamicVirtualDevice::DebugPort(
+            virtdev::debug::DebugPort::new(0x402)
+                .expect("Failed to make DebugPort"),
+        ),
+    ));
+
+    virtual_devices.push(RwLock::new(virtdev::DynamicVirtualDevice::Uart(
+        virtdev::com::Uart8250::new(0x3F8).expect("Failed to make Uart"),
+    )));
 
     let mut fw_cfg_builder = virtdev::qemu_fw_cfg::QemuFwCfgBuilder::new();
 
@@ -155,7 +125,9 @@ fn build_vm(
     )
     .unwrap();
 
-    device_map.register_device(fw_cfg_builder.build()).unwrap();
+    virtual_devices.push(RwLock::new(virtdev::DynamicVirtualDevice::Qemu(
+        fw_cfg_builder.build().expect("Failed to build FW Cfg"),
+    )));
 
     vm::VirtualMachine::new(vm_id, config, info).expect("Failed to create vm")
 }
@@ -251,8 +223,6 @@ unsafe fn kmain(mut boot_info: BootInfo) -> ! {
     ioapic::map_gsi_vector(interrupt::gsi::UART, interrupt::vector::UART, 0)
         .expect("Failed to map com0 gsi");
 
-    let mut builder = vm::VirtualMachineSetBuilder::new();
-
     let raw_cfg = boot_info
         .find_module("mythril.cfg")
         .expect("Failed to find 'mythril.cfg' in boot information")
@@ -263,13 +233,15 @@ unsafe fn kmain(mut boot_info: BootInfo) -> ! {
 
     debug!("mythril.cfg: {:?}", mythril_cfg);
 
-    for (num, vm) in mythril_cfg.vms.into_iter().enumerate() {
-        builder
-            .insert_machine(build_vm(num as u32, &vm, &boot_info, num == 0))
-            .expect("Failed to insert new vm");
-    }
-
-    vm::init_virtual_machines(builder.finalize());
+    let vms = mythril_cfg
+        .vms
+        .into_iter()
+        .enumerate()
+        .map(|(num, vm_cfg)| {
+            build_vm(num as u32, &vm_cfg, &boot_info, num == 0)
+        });
+    vm::init_virtual_machines(vms)
+        .expect("Failed to initialize early virtual machine state");
 
     debug!("AP_STARTUP address: 0x{:x}", AP_STARTUP_ADDR);
 
@@ -332,5 +304,17 @@ unsafe fn kmain(mut boot_info: BootInfo) -> ! {
         core::ptr::write_volatile(&mut AP_READY as *mut u8, 0);
     }
 
+    // Also don't start the bsp core if there is no guest assigned to use it
+    let bsp_core_id = percore::read_core_id();
+    if !vm::virtual_machines().is_assigned_core_id(bsp_core_id) {
+        debug!(
+            "Not starting core ID '{}' because it is not assigned to a guest",
+            bsp_core_id
+        );
+        loop {
+            crate::lock::relax_cpu();
+        }
+    }
+
     vcpu::mp_entry_point()
 }

mythril/src/kmain.rs

@@ -5,6 +5,8 @@
 #![feature(get_mut_unchecked)]
 #![feature(fixed_size_array)]
 #![feature(panic_info_message)]
+#![feature(pin_static_ref)]
+#![feature(array_value_iter)]
 #![feature(alloc_error_handler)]
 #![feature(lang_items)]
 #![feature(stmt_expr_attributes)]

mythril/src/lib.rs

@@ -61,20 +61,22 @@ pub unsafe fn init_sections(ncores: usize) -> Result<()> {
     Ok(())
 }
 
+unsafe fn percore_section_start(core_idx: u64) -> *const u8 {
+    if core_idx == 0 {
+        &PER_CORE_START as *const u8
+    } else {
+        let section_len = per_core_section_len();
+        (&AP_PER_CORE_SECTIONS[section_len * (core_idx - 1) as usize])
+            as *const u8
+    }
+}
+
 /// Initialize this core's per-core data
 ///
 /// This must be called by each AP (and the BSP) before
 /// the usage of any per-core variable
 pub unsafe fn init_segment_for_core(core_idx: u64) {
-    let fs = if core_idx == 0 {
-        &PER_CORE_START as *const u8 as u64
-    } else {
-        let section_len = per_core_section_len();
-        (&AP_PER_CORE_SECTIONS[section_len * (core_idx - 1) as usize])
-            as *const u8 as u64
-    };
-
-    msr::wrmsr(msr::IA32_FS_BASE, fs);
+    msr::wrmsr(msr::IA32_FS_BASE, percore_section_start(core_idx) as u64);
 
     RoAfterInit::init(
         crate::get_per_core_mut!(CORE_ID),
@@ -125,7 +127,9 @@ macro_rules! get_per_core {
     ($name:ident) => {
         #[allow(unused_unsafe)]
         unsafe {
-            $crate::percore::get_per_core_impl(&$name)
+            $crate::percore::get_per_core_impl(&paste::paste! {
+                [<PERCORE_ $name>]
+            })
         }
     };
 }
@@ -135,7 +139,9 @@ macro_rules! get_per_core_mut {
     ($name:ident) => {
         #[allow(unused_unsafe)]
         unsafe {
-            $crate::percore::get_per_core_mut_impl(&mut $name)
+            $crate::percore::get_per_core_mut_impl(&mut paste::paste! {
+                [<PERCORE_ $name>]
+            })
         }
     };
 }
@@ -145,14 +151,19 @@ macro_rules! get_per_core_mut {
 #[doc(hidden)]
 macro_rules! __declare_per_core_internal {
     ($(#[$attr:meta])* ($($vis:tt)*) static mut $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        #[link_section = ".per_core"]
-        $($vis)* static mut $N: $T = $e;
+        paste::paste! {
+            #[link_section = ".per_core"]
+            $($vis)* static mut [<PERCORE_ $N>]: $T = $e;
+        }
 
         declare_per_core!($($t)*);
     };
     ($(#[$attr:meta])* ($($vis:tt)*) static $N:ident : $T:ty = $e:expr; $($t:tt)*) => {
-        #[link_section = ".per_core"]
-        $($vis)* static $N: $T = $e;
+        use paste::paste;
+        paste! {
+            #[link_section = ".per_core"]
+            $($vis)* static [<PERCORE_ $N>]: $T = $e;
+        }
 
         declare_per_core!($($t)*);
     };

mythril/src/percore.rs

@@ -289,7 +289,7 @@ impl TimerWheel {
     /// expired and will reset any periodic timers.
     pub fn expire_elapsed_timers(
         &mut self,
-    ) -> Result<vec::Vec<TimerInterruptType>> {
+    ) -> Result<impl Iterator<Item = TimerInterruptType>> {
         let mut interrupts = vec![];
         let elapsed_oneshots = self
             .timers
@@ -318,7 +318,7 @@ impl TimerWheel {
         }
 
         self.update_interrupt_timer();
-        Ok(interrupts)
+        Ok(interrupts.into_iter())
     }
 
     fn update_interrupt_timer(&mut self) {