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vmm: cpu: Save and restore CPU states during snapshot/restore

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Based on recent KVM host patches (merged in Linux 5.16), it's forbidden
to call into KVM_SET_CPUID2 after the first successful KVM_RUN returned.
That means saving CPU states during the pause sequence, and restoring
these states during the resume sequence will not work with the current
design starting with kernel version 5.16.

In order to solve this problem, let's simply move the save/restore logic
to the snapshot/restore sequences rather than the pause/resume ones.

Signed-off-by: Sebastien Boeuf <sebastien.boeuf@intel.com>
This commit is contained in:
Sebastien Boeuf 2022-05-31 13:40:14 +02:00 committed by Rob Bradford
parent 3edaa8adb6
commit 65dc1c83a9
1 changed files with 17 additions and 22 deletions
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39
vmm/src/cpu.rs
View File

@ -375,43 +375,38 @@ 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.vcpu.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.vcpu.set_state(vcpu_state).map_err(|e| {
MigratableError::Pause(anyhow!("Could not set the vCPU state {:?}", e))
})?;
}
Ok(())
}
}
impl Pausable for Vcpu {}
impl Snapshottable for Vcpu {
fn id(&self) -> String {
VCPU_SNAPSHOT_ID.to_string()
}
fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
let saved_state = self
.vcpu
.state()
.map_err(|e| MigratableError::Pause(anyhow!("Could not get vCPU state {:?}", e)))?;
let mut vcpu_snapshot = Snapshot::new(&format!("{}", self.id));
vcpu_snapshot.add_data_section(SnapshotDataSection::new_from_state(
VCPU_SNAPSHOT_ID,
&self.saved_state,
&saved_state,
)?);
self.saved_state = Some(saved_state);
Ok(vcpu_snapshot)
}
fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
self.saved_state = Some(snapshot.to_state(VCPU_SNAPSHOT_ID)?);
let saved_state: CpuState = snapshot.to_state(VCPU_SNAPSHOT_ID)?;
self.vcpu
.set_state(&saved_state)
.map_err(|e| MigratableError::Pause(anyhow!("Could not set the vCPU state {:?}", e)))?;
self.saved_state = Some(saved_state);
Ok(())
}
}