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hypervisor: Define a VM-Exit abstraction

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In order to move the hypervisor specific parts of the VM exit handling
path, we're defining a generic, hypervisor agnostic VM exit enum.

This is what the hypervisor's Vcpu run() call should return when the VM
exit can not be completely handled through the hypervisor specific bits.
For KVM based hypervisors, this means directly forwarding the IO related
exits back to the VMM itself. For other hypervisors that e.g. rely on the
VMM to decode and emulate instructions, this means the decoding itself
would happen in the hypervisor crate exclusively, and the rest of the VM
exit handling would be handled through the VMM device model implementation.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

Fix test_vm unit test by using the new abstraction and dropping some
dead code.

Signed-off-by: Wei Liu <liuwe@microsoft.com>
This commit is contained in:
Wei Liu 2020-07-03 16:27:53 +02:00 committed by Rob Bradford
parent cfa758fbb1
commit a4f484bc5e
5 changed files with 83 additions and 88 deletions
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26
hypervisor/src/cpu.rs
View File

@ -10,7 +10,7 @@
#[cfg(target_arch = "aarch64")]
use crate::aarch64::VcpuInit;
use crate::{CpuState, MpState, VcpuExit};
use crate::{CpuState, MpState};
#[cfg(target_arch = "x86_64")]
use crate::x86_64::{
@ -18,7 +18,6 @@ use crate::x86_64::{
StandardRegisters, VcpuEvents, Xsave,
};
use thiserror::Error;
use vmm_sys_util::errno::Error as RunError;
#[derive(Error, Debug)]
///
@ -151,6 +150,20 @@ pub enum HypervisorCpuError {
NotifyGuestClockPaused(#[source] anyhow::Error),
}
#[derive(Debug)]
pub enum VmExit<'a> {
#[cfg(target_arch = "x86_64")]
IoOut(u16 /* port */, &'a [u8] /* data */),
#[cfg(target_arch = "x86_64")]
IoIn(u16 /* port */, &'a mut [u8] /* data */),
#[cfg(target_arch = "x86_64")]
IoapicEoi(u8 /* vector */),
MmioRead(u64 /* address */, &'a mut [u8]),
MmioWrite(u64 /* address */, &'a [u8]),
Ignore,
Reset,
}
///
/// Result type for returning from a function
///
@ -248,10 +261,6 @@ pub trait Vcpu: Send + Sync {
/// X86 specific call that sets the vcpu's current "xcrs".
///
fn set_xcrs(&self, xcrs: &ExtendedControlRegisters) -> Result<()>;
///
/// Triggers the running of the current virtual CPU returning an exit reason.
///
fn run(&self) -> std::result::Result<VcpuExit, RunError>;
#[cfg(target_arch = "x86_64")]
///
/// Returns currently pending exceptions, interrupts, and NMIs as well as related
@ -295,4 +304,9 @@ pub trait Vcpu: Send + Sync {
/// This function is required when restoring the VM
///
fn set_state(&self, state: &CpuState) -> Result<()>;
///
/// Triggers the running of the current virtual CPU returning an exit reason.
///
fn run(&self) -> std::result::Result<VmExit, HypervisorCpuError>;
}

47
hypervisor/src/kvm/mod.rs
View File

@ -564,8 +564,51 @@ impl cpu::Vcpu for KvmVcpu {
///
/// Triggers the running of the current virtual CPU returning an exit reason.
///
fn run(&self) -> std::result::Result<VcpuExit, vmm_sys_util::errno::Error> {
self.fd.run()
fn run(&self) -> std::result::Result<cpu::VmExit, cpu::HypervisorCpuError> {
match self.fd.run() {
Ok(run) => match run {
#[cfg(target_arch = "x86_64")]
VcpuExit::IoIn(addr, data) => Ok(cpu::VmExit::IoIn(addr, data)),
#[cfg(target_arch = "x86_64")]
VcpuExit::IoOut(addr, data) => Ok(cpu::VmExit::IoOut(addr, data)),
#[cfg(target_arch = "x86_64")]
VcpuExit::IoapicEoi(vector) => Ok(cpu::VmExit::IoapicEoi(vector)),
#[cfg(target_arch = "x86_64")]
VcpuExit::Shutdown | VcpuExit::Hlt => Ok(cpu::VmExit::Reset),
#[cfg(target_arch = "aarch64")]
VcpuExit::SystemEvent(event_type, flags) => {
use kvm_bindings::KVM_SYSTEM_EVENT_SHUTDOWN;
// On Aarch64, when the VM is shutdown, run() returns
// VcpuExit::SystemEvent with reason KVM_SYSTEM_EVENT_SHUTDOWN
if event_type == KVM_SYSTEM_EVENT_SHUTDOWN {
Ok(cpu::VmExit::Reset)
} else {
Err(cpu::HypervisorCpuError::RunVcpu(anyhow!(
"Unexpected system event with type 0x{:x}, flags 0x{:x}",
event_type,
flags
)))
}
}
VcpuExit::MmioRead(addr, data) => Ok(cpu::VmExit::MmioRead(addr, data)),
VcpuExit::MmioWrite(addr, data) => Ok(cpu::VmExit::MmioWrite(addr, data)),
r => Err(cpu::HypervisorCpuError::RunVcpu(anyhow!(
"Unexpected exit reason on vcpu run: {:?}",
r
))),
},
Err(ref e) => match e.errno() {
libc::EAGAIN | libc::EINTR => Ok(cpu::VmExit::Ignore),
_ => Err(cpu::HypervisorCpuError::RunVcpu(anyhow!(
"VCPU error {:?}",
e
))),
},
}
}
#[cfg(target_arch = "x86_64")]
///

4
hypervisor/src/lib.rs
View File

@ -22,6 +22,8 @@ extern crate serde;
extern crate serde_derive;
extern crate serde_json;
extern crate thiserror;
#[macro_use]
extern crate anyhow;
/// KVM implementation module
pub mod kvm;
@ -39,6 +41,6 @@ pub mod arch;
mod cpu;
pub use crate::hypervisor::{Hypervisor, HypervisorError};
pub use cpu::{HypervisorCpuError, Vcpu};
pub use cpu::{HypervisorCpuError, Vcpu, VmExit};
pub use kvm::*;
pub use vm::{DataMatch, HypervisorVmError, Vm};

52
vmm/src/cpu.rs
View File

@ -25,11 +25,9 @@ use arch::EntryPoint;
#[cfg(target_arch = "x86_64")]
use arch::{CpuidPatch, CpuidReg};
use devices::{interrupt_controller::InterruptController, BusDevice};
#[cfg(target_arch = "aarch64")]
use hypervisor::kvm::kvm_bindings::KVM_SYSTEM_EVENT_SHUTDOWN;
#[cfg(target_arch = "x86_64")]
use hypervisor::CpuId;
use hypervisor::{CpuState, VcpuExit};
use hypervisor::{CpuState, VmExit};
use libc::{c_void, siginfo_t};
@ -124,9 +122,6 @@ pub enum Error {
/// Error configuring VCPU
VcpuConfiguration(arch::Error),
/// Unexpected KVM_RUN exit reason
VcpuUnhandledKvmExit,
/// Failed to join on vCPU threads
ThreadCleanup(std::boxed::Box<dyn std::any::Any + std::marker::Send>),
@ -322,28 +317,28 @@ impl Vcpu {
match self.vcpu.run() {
Ok(run) => match run {
#[cfg(target_arch = "x86_64")]
VcpuExit::IoIn(addr, data) => {
VmExit::IoIn(addr, data) => {
self.io_bus.read(u64::from(addr), data);
Ok(true)
}
#[cfg(target_arch = "x86_64")]
VcpuExit::IoOut(addr, data) => {
VmExit::IoOut(addr, data) => {
if addr == DEBUG_IOPORT && data.len() == 1 {
self.log_debug_ioport(data[0]);
}
self.io_bus.write(u64::from(addr), data);
Ok(true)
}
VcpuExit::MmioRead(addr, data) => {
VmExit::MmioRead(addr, data) => {
self.mmio_bus.read(addr as u64, data);
Ok(true)
}
VcpuExit::MmioWrite(addr, data) => {
VmExit::MmioWrite(addr, data) => {
self.mmio_bus.write(addr as u64, data);
Ok(true)
}
#[cfg(target_arch = "x86_64")]
VcpuExit::IoapicEoi(vector) => {
VmExit::IoapicEoi(vector) => {
if let Some(interrupt_controller) = &self.interrupt_controller {
interrupt_controller
.lock()
@ -352,37 +347,12 @@ impl Vcpu {
}
Ok(true)
}
VcpuExit::Shutdown => {
// Triple fault to trigger a reboot
Ok(false)
}
#[cfg(target_arch = "aarch64")]
VcpuExit::SystemEvent(event_type, flags) => {
// On Aarch64, when the VM is shutdown, run() returns
// VcpuExit::SystemEvent with reason KVM_SYSTEM_EVENT_SHUTDOWN
if event_type == KVM_SYSTEM_EVENT_SHUTDOWN {
Ok(false)
} else {
error!(
"Unexpected system event with type 0x{:x}, flags 0x{:x}",
event_type, flags
);
Err(Error::VcpuUnhandledKvmExit)
}
}
r => {
error!("Unexpected exit reason on vcpu run: {:?}", r);
Err(Error::VcpuUnhandledKvmExit)
}
VmExit::Ignore => Ok(true),
VmExit::Reset => Ok(false),
},
Err(ref e) => match e.errno() {
libc::EAGAIN | libc::EINTR => Ok(true),
_ => {
error!("VCPU {:?} error {:?}", self.id, e);
Err(Error::VcpuUnhandledKvmExit)
}
},
Err(e) => Err(Error::VcpuRun(e.into())),
}
}
@ -846,7 +816,7 @@ impl CpuManager {
break;
}
// vcpu.run() returns false on a KVM_EXIT_SHUTDOWN (triple-fault) so trigger a reset
// vcpu.run() returns false on a triple-fault so trigger a reset
match vcpu.lock().unwrap().run() {
Err(e) => {
error!("VCPU generated error: {:?}", e);

42
vmm/src/vm.rs
View File

@ -1429,7 +1429,7 @@ mod tests {
#[cfg(target_arch = "x86_64")]
#[test]
pub fn test_vm() {
use hypervisor::VcpuExit;
use hypervisor::VmExit;
use vm_memory::{GuestMemory, GuestMemoryRegion};
// This example based on https://lwn.net/Articles/658511/
let code = [
@ -1481,52 +1481,18 @@ pub fn test_vm() {
loop {
match vcpu.run().expect("run failed") {
VcpuExit::IoIn(addr, data) => {
println!(
"IO in -- addr: {:#x} data [{:?}]",
addr,
str::from_utf8(&data).unwrap()
);
}
VcpuExit::IoOut(addr, data) => {
VmExit::IoOut(addr, data) => {
println!(
"IO out -- addr: {:#x} data [{:?}]",
addr,
str::from_utf8(&data).unwrap()
);
}
VcpuExit::MmioRead(_addr, _data) => {}
VcpuExit::MmioWrite(_addr, _data) => {}
VcpuExit::Unknown => {}
VcpuExit::Exception => {}
VcpuExit::Hypercall => {}
VcpuExit::Debug => {}
VcpuExit::Hlt => {
VmExit::Reset => {
println!("HLT");
break;
}
VcpuExit::IrqWindowOpen => {}
VcpuExit::Shutdown => {}
VcpuExit::FailEntry => {}
VcpuExit::Intr => {}
VcpuExit::SetTpr => {}
VcpuExit::TprAccess => {}
VcpuExit::S390Sieic => {}
VcpuExit::S390Reset => {}
VcpuExit::Dcr => {}
VcpuExit::Nmi => {}
VcpuExit::InternalError => {}
VcpuExit::Osi => {}
VcpuExit::PaprHcall => {}
VcpuExit::S390Ucontrol => {}
VcpuExit::Watchdog => {}
VcpuExit::S390Tsch => {}
VcpuExit::Epr => {}
VcpuExit::SystemEvent(_, _) => {}
VcpuExit::S390Stsi => {}
VcpuExit::IoapicEoi(_vector) => {}
VcpuExit::Hyperv => {}
r => panic!("unexpected exit reason: {:?}", r),
}
// r => panic!("unexpected exit reason: {:?}", r),
}
}