kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks
kvm_hc_kick_cpu allows the calling vcpu to kick another vcpu out of halt state.
the presence of these hypercalls is indicated to guest via
kvm_feature_pv_unhalt.
Fold pv_unhalt flag into GET_MP_STATE ioctl to aid migration
During migration, any vcpu that got kicked but did not become runnable
(still in halted state) should be runnable after migration.
Signed-off-by: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Signed-off-by: Suzuki Poulose <suzuki@in.ibm.com>
[Raghu: Apic related changes, folding pvunhalted into vcpu_runnable
Added flags for future use (suggested by Gleb)]
[ Raghu: fold pv_unhalt flag as suggested by Eric Northup]
Signed-off-by: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: Gleb Natapov <gleb@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 668f19a..c537417 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5588,6 +5588,36 @@
return 1;
}
+/*
+ * kvm_pv_kick_cpu_op: Kick a vcpu.
+ *
+ * @apicid - apicid of vcpu to be kicked.
+ */
+static void kvm_pv_kick_cpu_op(struct kvm *kvm, unsigned long flags, int apicid)
+{
+ struct kvm_vcpu *vcpu = NULL;
+ int i;
+
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ if (!kvm_apic_present(vcpu))
+ continue;
+
+ if (kvm_apic_match_dest(vcpu, 0, 0, apicid, 0))
+ break;
+ }
+ if (vcpu) {
+ /*
+ * Setting unhalt flag here can result in spurious runnable
+ * state when unhalt reset does not happen in vcpu_block.
+ * But that is harmless since that should soon result in halt.
+ */
+ vcpu->arch.pv.pv_unhalted = true;
+ /* We need everybody see unhalt before vcpu unblocks */
+ smp_wmb();
+ kvm_vcpu_kick(vcpu);
+ }
+}
+
int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
{
unsigned long nr, a0, a1, a2, a3, ret;
@@ -5621,6 +5651,10 @@
case KVM_HC_VAPIC_POLL_IRQ:
ret = 0;
break;
+ case KVM_HC_KICK_CPU:
+ kvm_pv_kick_cpu_op(vcpu->kvm, a0, a1);
+ ret = 0;
+ break;
default:
ret = -KVM_ENOSYS;
break;
@@ -6043,6 +6077,7 @@
kvm_apic_accept_events(vcpu);
switch(vcpu->arch.mp_state) {
case KVM_MP_STATE_HALTED:
+ vcpu->arch.pv.pv_unhalted = false;
vcpu->arch.mp_state =
KVM_MP_STATE_RUNNABLE;
case KVM_MP_STATE_RUNNABLE:
@@ -6342,7 +6377,12 @@
struct kvm_mp_state *mp_state)
{
kvm_apic_accept_events(vcpu);
- mp_state->mp_state = vcpu->arch.mp_state;
+ if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED &&
+ vcpu->arch.pv.pv_unhalted)
+ mp_state->mp_state = KVM_MP_STATE_RUNNABLE;
+ else
+ mp_state->mp_state = vcpu->arch.mp_state;
+
return 0;
}
@@ -6863,6 +6903,7 @@
BUG_ON(vcpu->kvm == NULL);
kvm = vcpu->kvm;
+ vcpu->arch.pv.pv_unhalted = false;
vcpu->arch.emulate_ctxt.ops = &emulate_ops;
if (!irqchip_in_kernel(kvm) || kvm_vcpu_is_bsp(vcpu))
vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE;
@@ -7200,6 +7241,7 @@
!vcpu->arch.apf.halted)
|| !list_empty_careful(&vcpu->async_pf.done)
|| kvm_apic_has_events(vcpu)
+ || vcpu->arch.pv.pv_unhalted
|| atomic_read(&vcpu->arch.nmi_queued) ||
(kvm_arch_interrupt_allowed(vcpu) &&
kvm_cpu_has_interrupt(vcpu));