KVM: x86/xen: Add support for vCPU runstate information
This is how Xen guests do steal time accounting. The hypervisor records
the amount of time spent in each of running/runnable/blocked/offline
states.
In the Xen accounting, a vCPU is still in state RUNSTATE_running while
in Xen for a hypercall or I/O trap, etc. Only if Xen explicitly schedules
does the state become RUNSTATE_blocked. In KVM this means that even when
the vCPU exits the kvm_run loop, the state remains RUNSTATE_running.
The VMM can explicitly set the vCPU to RUNSTATE_blocked by using the
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_CURRENT attribute, and can also use
KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST to retrospectively add a given
amount of time to the blocked state and subtract it from the running
state.
The state_entry_time corresponds to get_kvmclock_ns() at the time the
vCPU entered the current state, and the total times of all four states
should always add up to state_entry_time.
Co-developed-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Message-Id: <20210301125309.874953-2-dwmw2@infradead.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 4a5ce57..868213c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2956,6 +2956,11 @@ static void record_steal_time(struct kvm_vcpu *vcpu)
struct kvm_host_map map;
struct kvm_steal_time *st;
+ if (kvm_xen_msr_enabled(vcpu->kvm)) {
+ kvm_xen_runstate_set_running(vcpu);
+ return;
+ }
+
if (!(vcpu->arch.st.msr_val & KVM_MSR_ENABLED))
return;
@@ -3760,6 +3765,8 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
r = KVM_XEN_HVM_CONFIG_HYPERCALL_MSR |
KVM_XEN_HVM_CONFIG_INTERCEPT_HCALL |
KVM_XEN_HVM_CONFIG_SHARED_INFO;
+ if (sched_info_on())
+ r |= KVM_XEN_HVM_CONFIG_RUNSTATE;
break;
#endif
case KVM_CAP_SYNC_REGS:
@@ -4039,7 +4046,11 @@ void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
if (vcpu->preempted && !vcpu->arch.guest_state_protected)
vcpu->arch.preempted_in_kernel = !static_call(kvm_x86_get_cpl)(vcpu);
- kvm_steal_time_set_preempted(vcpu);
+ if (kvm_xen_msr_enabled(vcpu->kvm))
+ kvm_xen_runstate_set_preempted(vcpu);
+ else
+ kvm_steal_time_set_preempted(vcpu);
+
static_call(kvm_x86_vcpu_put)(vcpu);
vcpu->arch.last_host_tsc = rdtsc();
/*