External/cloud-hypervisor
1
0
Fork 0
mirror of https://github.com/cloud-hypervisor/cloud-hypervisor.git synced 2025-01-10 14:47:42 +00:00
Code Issues Packages Projects Releases Wiki Activity

vmm: Save and restore vCPU states during pause/resume operations

Browse Source 
We need consistency between pause/resume and snapshot/restore
operations. The symmetrical behavior of pausing/snapshotting
and restoring/resuming has been introduced recently, and we must
now ensure that no matter if we're using pause/resume or
snapshot/restore features, the resulting VM should be running in
the exact same way.

That's why the vCPU state is now stored upon VM pausing. The snapshot
operation being a simple serialization of the previously saved state.
The same way, the vCPU state is now restored upon VM resuming. The
restore operation being a simple deserialization of the previously
restored state.

It's interesting to note that this patch ensures time consistency from a
guest perspective, no matter which clocksource is being used. From a
previous patch, the KVM clock was saved/restored upon VM pause/resume.
We now have the same behavior for TSC, as the TSC from the vCPUs are
saved/restored upon VM pause/resume too.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2020-06-24 13:55:18 +02:00
parent 18e7d7a1f7
commit f6eeba781b
1 changed files with 17 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
vmm/src/cpu.rs
View File

@ -29,7 +29,7 @@ use devices::{interrupt_controller::InterruptController, BusDevice};
use hypervisor::kvm::kvm_bindings::KVM_SYSTEM_EVENT_SHUTDOWN;
#[cfg(target_arch = "x86_64")]
use hypervisor::CpuId;
use hypervisor::VcpuExit;
use hypervisor::{CpuState, VcpuExit};
use libc::{c_void, siginfo_t};
@ -243,6 +243,7 @@ pub struct Vcpu {
vm_ts: std::time::Instant,
#[cfg(target_arch = "aarch64")]
mpidr: u64,
saved_state: Option<CpuState>,
}
impl Vcpu {
@ -272,6 +273,7 @@ impl Vcpu {
vm_ts: creation_ts,
#[cfg(target_arch = "aarch64")]
mpidr: 0,
saved_state: None,
})))
}
@ -400,10 +402,21 @@ impl Vcpu {
const VCPU_SNAPSHOT_ID: &str = "vcpu";
impl Pausable for Vcpu {
fn pause(&mut self) -> std::result::Result<(), MigratableError> {
self.saved_state =
Some(self.fd.cpu_state().map_err(|e| {
MigratableError::Pause(anyhow!("Could not get vCPU state {:?}", e))
})?);
Ok(())
}
fn resume(&mut self) -> std::result::Result<(), MigratableError> {
if let Some(vcpu_state) = &self.saved_state {
self.fd.set_cpu_state(vcpu_state).map_err(|e| {
MigratableError::Pause(anyhow!("Could not set the vCPU state {:?}", e))
})?;
}
Ok(())
}
}
@ -413,10 +426,8 @@ impl Snapshottable for Vcpu {
}
fn snapshot(&self) -> std::result::Result<Snapshot, MigratableError> {
let snapshot = serde_json::to_vec(&self.fd.cpu_state().map_err(|e| {
MigratableError::Snapshot(anyhow!("Could not get vCPU KVM state {:?}", e))
})?)
.map_err(|e| MigratableError::Snapshot(e.into()))?;
let snapshot = serde_json::to_vec(&self.saved_state)
.map_err(|e| MigratableError::Snapshot(e.into()))?;
let mut vcpu_snapshot = Snapshot::new(&format!("{}", self.id));
vcpu_snapshot.add_data_section(SnapshotDataSection {
@ -442,9 +453,7 @@ impl Snapshottable for Vcpu {
}
};
self.fd.set_cpu_state(&vcpu_state).map_err(|e| {
MigratableError::Restore(anyhow!("Could not set the vCPU KVM state {:?}", e))
})?;
self.saved_state = Some(vcpu_state);
Ok(())
} else {