From: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx>
The vcpu can be safely released when
--1.guest tells us that the vcpu is not needed any longer.
--2.vcpu hits the last instruction _halt_
If both of the conditions are satisfied, kvm exits to userspace
with the reason vcpu dead. So the user thread can exit safely.
Signed-off-by: Liu Ping Fan <pingfank@xxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 16 ++++++++++++++++
include/linux/kvm.h | 11 +++++++++++
include/linux/kvm_host.h | 1 +
3 files changed, 28 insertions(+), 0 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ea2315a..7948eaf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5825,11 +5825,27 @@ static int __vcpu_run(struct kvm_vcpu *vcpu)
!vcpu->arch.apf.halted)
r = vcpu_enter_guest(vcpu);
else {
+retry:
+ if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED) {
+ /*1st check whether guest notify CPU_DEAD*/
+ if (vcpu->state == KVM_VCPU_STATE_DYING) {
+ vcpu->state = KVM_VCPU_STATE_DEAD;
+ vcpu->run->exit_reason = KVM_EXIT_VCPU_DEAD;
+ break;
+ }
+ }
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
kvm_vcpu_block(vcpu);
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);
if (kvm_check_request(KVM_REQ_UNHALT, vcpu))
{
+ switch (vcpu->state) {
+ case KVM_VCPU_STATE_DYING:
+ r = 1;
+ goto retry;
+ default:
+ break;
+ }
switch(vcpu->arch.mp_state) {
case KVM_MP_STATE_HALTED:
vcpu->arch.mp_state =
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index c3892fc..d5ff3f7 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -162,6 +162,7 @@ struct kvm_pit_config {
#define KVM_EXIT_INTERNAL_ERROR 17
#define KVM_EXIT_OSI 18
#define KVM_EXIT_PAPR_HCALL 19
+#define KVM_EXIT_VCPU_DEAD 20
/* For KVM_EXIT_INTERNAL_ERROR */
#define KVM_INTERNAL_ERROR_EMULATION 1
@@ -334,6 +335,12 @@ struct kvm_signal_mask {
__u8 sigset[0];
};
+/*for KVM_VCPU_SET_STATE */
+struct kvm_vcpu_state {
+ int vcpu_id;
+ int state;
+};
+
/* for KVM_TPR_ACCESS_REPORTING */
struct kvm_tpr_access_ctl {
__u32 enabled;
@@ -354,6 +361,9 @@ struct kvm_vapic_addr {
#define KVM_MP_STATE_HALTED 3
#define KVM_MP_STATE_SIPI_RECEIVED 4
+#define KVM_VCPU_STATE_DYING 1
+#define KVM_VCPU_STATE_DEAD 2
+
struct kvm_mp_state {
__u32 mp_state;
};
@@ -762,6 +772,7 @@ struct kvm_clock_data {
#define KVM_CREATE_SPAPR_TCE _IOW(KVMIO, 0xa8, struct kvm_create_spapr_tce)
/* Available with KVM_CAP_RMA */
#define KVM_ALLOCATE_RMA _IOR(KVMIO, 0xa9, struct kvm_allocate_rma)
+#define KVM_SETSTATE_VCPU _IOW(KVMIO, 0xaa, struct kvm_vcpu_state)
#define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index fe35078..6fdf927 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -114,6 +114,7 @@ enum {
struct kvm_vcpu {
struct kvm *kvm;
struct kref refcount;
+ int state;
#ifdef CONFIG_PREEMPT_NOTIFIERS
struct preempt_notifier preempt_notifier;
#endif
--
1.7.4.4
--
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