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hypervisor, vmm: Remove shared ownership of VmmOps

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This interface is used by the vCPU thread to delegate responsibility for
handling MMIO/PIO operations and to support different approaches than a
VM exit.

During profiling I found that we were spending 13.75% of the boot CPU
uage acquiring access to the object holding the VmmOps via
ArcSwap::load_full()

    13.75%     6.02%  vcpu0            cloud-hypervisor    [.] arc_swap::ArcSwapAny<T,S>::load_full
            |
            ---arc_swap::ArcSwapAny<T,S>::load_full
               |
                --13.43%--<hypervisor::kvm::KvmVcpu as hypervisor::cpu::Vcpu>::run
                          std::sys_common::backtrace::__rust_begin_short_backtrace
                          core::ops::function::FnOnce::call_once{{vtable-shim}}
                          std::sys::unix:🧵:Thread:🆕:thread_start

However since the object implementing VmmOps does not need to be mutable
and it is only used from the vCPU side we can change the ownership to
being a simple Arc<> that is passed in when calling create_vcpu().

This completely removes the above CPU usage from subsequent profiles.

Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This commit is contained in:
Rob Bradford 2020-11-18 16:37:52 +00:00 committed by Samuel Ortiz
parent 6a591ca81d
commit 0fec326582
5 changed files with 46 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
hypervisor/src/kvm/mod.rs
View File

@ -19,7 +19,6 @@ use crate::hypervisor;
use crate::vm::{self, VmmOps};
#[cfg(target_arch = "aarch64")]
use crate::{arm64_core_reg_id, offset__of};
use arc_swap::ArcSwapOption;
use kvm_ioctls::{NoDatamatch, VcpuFd, VmFd};
use serde_derive::{Deserialize, Serialize};
use std::os::unix::io::{AsRawFd, RawFd};
@ -97,7 +96,6 @@ pub struct KvmVm {
#[cfg(target_arch = "x86_64")]
msrs: MsrEntries,
state: KvmVmState,
vmmops: Arc<ArcSwapOption<Box<dyn vm::VmmOps>>>,
}
// Returns a `Vec<T>` with a size in bytes at least as large as `size_in_bytes`.
@ -177,7 +175,11 @@ impl vm::Vm for KvmVm {
///
/// Creates a VcpuFd object from a vcpu RawFd.
///
fn create_vcpu(&self, id: u8) -> vm::Result<Arc<dyn cpu::Vcpu>> {
fn create_vcpu(
&self,
id: u8,
vmmops: Option<Arc<Box<dyn VmmOps>>>,
) -> vm::Result<Arc<dyn cpu::Vcpu>> {
let vc = self
.fd
.create_vcpu(id)
@ -186,7 +188,7 @@ impl vm::Vm for KvmVm {
fd: vc,
#[cfg(target_arch = "x86_64")]
msrs: self.msrs.clone(),
vmmops: self.vmmops.clone(),
vmmops,
#[cfg(target_arch = "x86_64")]
hyperv_synic: AtomicBool::new(false),
};
@ -362,13 +364,6 @@ impl vm::Vm for KvmVm {
Ok(())
}
///
/// Set the VmmOps interface
///
fn set_vmmops(&self, vmmops: Box<dyn VmmOps>) -> vm::Result<()> {
self.vmmops.store(Some(Arc::new(vmmops)));
Ok(())
}
///
/// Get dirty pages bitmap (one bit per page)
///
@ -454,7 +449,6 @@ impl hypervisor::Hypervisor for KvmHypervisor {
fd: vm_fd,
msrs,
state: VmState {},
vmmops: Arc::new(ArcSwapOption::from(None)),
}))
}
@ -463,7 +457,6 @@ impl hypervisor::Hypervisor for KvmHypervisor {
Ok(Arc::new(KvmVm {
fd: vm_fd,
state: VmState {},
vmmops: Arc::new(ArcSwapOption::from(None)),
}))
}
}
@ -524,7 +517,7 @@ pub struct KvmVcpu {
fd: VcpuFd,
#[cfg(target_arch = "x86_64")]
msrs: MsrEntries,
vmmops: Arc<ArcSwapOption<Box<dyn vm::VmmOps>>>,
vmmops: Option<Arc<Box<dyn vm::VmmOps>>>,
#[cfg(target_arch = "x86_64")]
hyperv_synic: AtomicBool,
}
@ -535,7 +528,7 @@ pub struct KvmVcpu {
/// let kvm = hypervisor::kvm::KvmHypervisor::new().unwrap();
/// let hypervisor: Arc<dyn hypervisor::Hypervisor> = Arc::new(kvm);
/// let vm = hypervisor.create_vm().expect("new VM fd creation failed");
/// let vcpu = vm.create_vcpu(0).unwrap();
/// let vcpu = vm.create_vcpu(0, None).unwrap();
/// vcpu.get/set().unwrap()
///
impl cpu::Vcpu for KvmVcpu {
@ -723,7 +716,7 @@ impl cpu::Vcpu for KvmVcpu {
Ok(run) => match run {
#[cfg(target_arch = "x86_64")]
VcpuExit::IoIn(addr, data) => {
if let Some(vmmops) = self.vmmops.load_full() {
if let Some(vmmops) = &self.vmmops {
return vmmops
.pio_read(addr.into(), data)
.map(|_| cpu::VmExit::Ignore)
@ -734,7 +727,7 @@ impl cpu::Vcpu for KvmVcpu {
}
#[cfg(target_arch = "x86_64")]
VcpuExit::IoOut(addr, data) => {
if let Some(vmmops) = self.vmmops.load_full() {
if let Some(vmmops) = &self.vmmops {
return vmmops
.pio_write(addr.into(), data)
.map(|_| cpu::VmExit::Ignore)
@ -767,7 +760,7 @@ impl cpu::Vcpu for KvmVcpu {
}
VcpuExit::MmioRead(addr, data) => {
if let Some(vmmops) = self.vmmops.load_full() {
if let Some(vmmops) = &self.vmmops {
return vmmops
.mmio_read(addr, data)
.map(|_| cpu::VmExit::Ignore)
@ -777,7 +770,7 @@ impl cpu::Vcpu for KvmVcpu {
Ok(cpu::VmExit::MmioRead(addr, data))
}
VcpuExit::MmioWrite(addr, data) => {
if let Some(vmmops) = self.vmmops.load_full() {
if let Some(vmmops) = &self.vmmops {
return vmmops
.mmio_write(addr, data)
.map(|_| cpu::VmExit::Ignore)
@ -1136,7 +1129,7 @@ impl cpu::Vcpu for KvmVcpu {
/// let hv: Arc<dyn hypervisor::Hypervisor> = Arc::new(kvm);
/// let vm = hv.create_vm().expect("new VM fd creation failed");
/// vm.enable_split_irq().unwrap();
/// let vcpu = vm.create_vcpu(0).unwrap();
/// let vcpu = vm.create_vcpu(0, None).unwrap();
/// let state = vcpu.state().unwrap();
/// ```
fn state(&self) -> cpu::Result<CpuState> {
@ -1282,7 +1275,7 @@ impl cpu::Vcpu for KvmVcpu {
/// let hv: Arc<dyn hypervisor::Hypervisor> = Arc::new(kvm);
/// let vm = hv.create_vm().expect("new VM fd creation failed");
/// vm.enable_split_irq().unwrap();
/// let vcpu = vm.create_vcpu(0).unwrap();
/// let vcpu = vm.create_vcpu(0, None).unwrap();
/// let state = vcpu.state().unwrap();
/// vcpu.set_state(&state).unwrap();
/// ```

4
hypervisor/src/vm.rs
View File

@ -174,7 +174,7 @@ pub trait Vm: Send + Sync {
/// Unregister an event that will, when signaled, trigger the `gsi` IRQ.
fn unregister_irqfd(&self, fd: &EventFd, gsi: u32) -> Result<()>;
/// Creates a new KVM vCPU file descriptor and maps the memory corresponding
fn create_vcpu(&self, id: u8) -> Result<Arc<dyn Vcpu>>;
fn create_vcpu(&self, id: u8, vmmops: Option<Arc<Box<dyn VmmOps>>>) -> Result<Arc<dyn Vcpu>>;
/// Registers an event to be signaled whenever a certain address is written to.
fn register_ioevent(
&self,
@ -220,8 +220,6 @@ pub trait Vm: Send + Sync {
fn state(&self) -> Result<VmState>;
/// Set the VM state
fn set_state(&self, state: VmState) -> Result<()>;
/// Set VmmOps interface
fn set_vmmops(&self, vmmops: Box<dyn VmmOps>) -> Result<()>;
/// Get dirty pages bitmap
fn get_dirty_log(&self, slot: u32, memory_size: u64) -> Result<Vec<u64>>;
}

39
vmm/src/cpu.rs
View File

@ -34,10 +34,9 @@ use devices::interrupt_controller::InterruptController;
use hypervisor::kvm::kvm_bindings;
#[cfg(target_arch = "x86_64")]
use hypervisor::CpuId;
use hypervisor::{CpuState, HypervisorCpuError, VmExit};
use seccomp::{SeccompAction, SeccompFilter};
use hypervisor::{vm::VmmOps, CpuState, HypervisorCpuError, VmExit};
use libc::{c_void, siginfo_t};
use seccomp::{SeccompAction, SeccompFilter};
use std::os::unix::thread::JoinHandleExt;
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, Barrier, Mutex};
@ -225,9 +224,14 @@ impl Vcpu {
///
/// * `id` - Represents the CPU number between [0, max vcpus).
/// * `vm` - The virtual machine this vcpu will get attached to.
pub fn new(id: u8, vm: &Arc<dyn hypervisor::Vm>) -> Result<Arc<Mutex<Self>>> {
/// * `vmmops` - Optional object for exit handling.
pub fn new(
id: u8,
vm: &Arc<dyn hypervisor::Vm>,
vmmops: Option<Arc<Box<dyn VmmOps>>>,
) -> Result<Arc<Mutex<Self>>> {
let vcpu = vm
.create_vcpu(id)
.create_vcpu(id, vmmops)
.map_err(|e| Error::VcpuCreate(e.into()))?;
// Initially the cpuid per vCPU is the one supported by this VM.
Ok(Arc::new(Mutex::new(Vcpu {
@ -405,6 +409,7 @@ pub struct CpuManager {
selected_cpu: u8,
vcpus: Vec<Arc<Mutex<Vcpu>>>,
seccomp_action: SeccompAction,
vmmops: Arc<Box<dyn VmmOps>>,
}
const CPU_ENABLE_FLAG: usize = 0;
@ -534,6 +539,7 @@ impl CpuManager {
reset_evt: EventFd,
hypervisor: Arc<dyn hypervisor::Hypervisor>,
seccomp_action: SeccompAction,
vmmops: Arc<Box<dyn VmmOps>>,
) -> Result<Arc<Mutex<CpuManager>>> {
let guest_memory = memory_manager.lock().unwrap().guest_memory();
let mut vcpu_states = Vec::with_capacity(usize::from(config.max_vcpus));
@ -565,6 +571,7 @@ impl CpuManager {
selected_cpu: 0,
vcpus: Vec::with_capacity(usize::from(config.max_vcpus)),
seccomp_action,
vmmops,
}));
#[cfg(target_arch = "x86_64")]
@ -656,7 +663,7 @@ impl CpuManager {
) -> Result<Arc<Mutex<Vcpu>>> {
info!("Creating vCPU: cpu_id = {}", cpu_id);
let vcpu = Vcpu::new(cpu_id, &self.vm)?;
let vcpu = Vcpu::new(cpu_id, &self.vm, Some(self.vmmops.clone()))?;
if let Some(snapshot) = snapshot {
// AArch64 vCPUs should be initialized after created.
@ -1429,7 +1436,7 @@ mod tests {
assert!(hv.check_capability(hypervisor::kvm::Cap::Irqchip));
// Calling get_lapic will fail if there is no irqchip before hand.
assert!(vm.create_irq_chip().is_ok());
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let klapic_before: LapicState = vcpu.get_lapic().unwrap();
// Compute the value that is expected to represent LVT0 and LVT1.
@ -1452,7 +1459,7 @@ mod tests {
fn test_setup_fpu() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().expect("new VM fd creation failed");
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
setup_fpu(&vcpu).unwrap();
let expected_fpu: FpuState = FpuState {
@ -1477,7 +1484,7 @@ mod tests {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().expect("new VM fd creation failed");
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
setup_msrs(&vcpu).unwrap();
// This test will check against the last MSR entry configured (the tenth one).
@ -1503,7 +1510,7 @@ mod tests {
fn test_setup_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().expect("new VM fd creation failed");
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let expected_regs: StandardRegisters = StandardRegisters {
rflags: 0x0000000000000002u64,
@ -1531,7 +1538,7 @@ mod tests {
fn test_setup_sregs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().expect("new VM fd creation failed");
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut expected_sregs: SpecialRegisters = vcpu.get_sregs().unwrap();
let gm = GuestMemoryMmap::from_ranges(&vec![(GuestAddress(0), 0x10000)]).unwrap();
@ -1562,7 +1569,7 @@ mod tests {
fn test_setup_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut regions = Vec::new();
regions.push((
GuestAddress(layout::RAM_64BIT_START),
@ -1585,7 +1592,7 @@ mod tests {
fn test_read_mpidr() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut kvi: kvm_vcpu_init = kvm_vcpu_init::default();
vm.get_preferred_target(&mut kvi).unwrap();
@ -1609,7 +1616,7 @@ mod tests {
fn test_save_restore_core_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut kvi: kvm_vcpu_init = kvm_vcpu_init::default();
vm.get_preferred_target(&mut kvi).unwrap();
@ -1645,7 +1652,7 @@ mod tests {
fn test_save_restore_system_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut kvi: kvm_vcpu_init = kvm_vcpu_init::default();
vm.get_preferred_target(&mut kvi).unwrap();
@ -1686,7 +1693,7 @@ mod tests {
fn test_get_set_mpstate() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let vcpu = vm.create_vcpu(0).unwrap();
let vcpu = vm.create_vcpu(0, None).unwrap();
let mut kvi: kvm_vcpu_init = kvm_vcpu_init::default();
vm.get_preferred_target(&mut kvi).unwrap();

8
vmm/src/interrupt.rs
View File

@ -415,7 +415,7 @@ mod tests {
fn test_get_set_dist_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let _ = vm.create_vcpu(0).unwrap();
let _ = vm.create_vcpu(0, None).unwrap();
let gic = create_gic(&vm, 1).expect("Cannot create gic");
let res = get_dist_regs(gic.device());
@ -431,7 +431,7 @@ mod tests {
fn test_get_set_redist_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let _ = vm.create_vcpu(0).unwrap();
let _ = vm.create_vcpu(0, None).unwrap();
let gic = create_gic(&vm, 1).expect("Cannot create gic");
let mut gicr_typer = Vec::new();
@ -449,7 +449,7 @@ mod tests {
fn test_get_set_icc_regs() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let _ = vm.create_vcpu(0).unwrap();
let _ = vm.create_vcpu(0, None).unwrap();
let gic = create_gic(&vm, 1).expect("Cannot create gic");
let mut gicr_typer = Vec::new();
@ -467,7 +467,7 @@ mod tests {
fn test_save_pending_tables() {
let hv = hypervisor::new().unwrap();
let vm = hv.create_vm().unwrap();
let _ = vm.create_vcpu(0).unwrap();
let _ = vm.create_vcpu(0, None).unwrap();
let gic = create_gic(&vm, 1).expect("Cannot create gic");
assert!(save_pending_tables(gic.device()).is_ok());

8
vmm/src/vm.rs
View File

@ -500,15 +500,14 @@ impl Vm {
let mmio_bus = Arc::clone(device_manager.lock().unwrap().mmio_bus());
// Create the VmOps structure, which implements the VmmOps trait.
// And send it to the hypervisor.
let vm_ops = Box::new(VmOps {
let vm_ops: Arc<Box<dyn VmmOps>> = Arc::new(Box::new(VmOps {
memory,
#[cfg(target_arch = "x86_64")]
io_bus,
mmio_bus,
#[cfg(target_arch = "x86_64")]
timestamp: std::time::Instant::now(),
});
vm.set_vmmops(vm_ops).map_err(Error::SetVmmOpsInterface)?;
}));
let exit_evt_clone = exit_evt.try_clone().map_err(Error::EventFdClone)?;
let cpu_manager = cpu::CpuManager::new(
@ -520,6 +519,7 @@ impl Vm {
reset_evt,
hypervisor,
seccomp_action.clone(),
vm_ops,
)
.map_err(Error::CpuManager)?;
@ -2187,7 +2187,7 @@ pub fn test_vm() {
mem.write_slice(&code, load_addr)
.expect("Writing code to memory failed");
let vcpu = vm.create_vcpu(0).expect("new Vcpu failed");
let vcpu = vm.create_vcpu(0, None).expect("new Vcpu failed");
let mut vcpu_sregs = vcpu.get_sregs().expect("get sregs failed");
vcpu_sregs.cs.base = 0;