[PATCH] KVM: x86: should release vcpu when closing vcpu fd

[Chen Fan <chen.fan.fnst@xxxxxxxxxxxxxx>]

If we want to remove a vcpu from vm, we should not be only to
put kvm, we need to decrease online vcpus and free struct kvm_vcpu
when closing a vcpu file descriptor.

Signed-off-by: Chen Fan <chen.fan.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/kvm/x86.c       | 14 ++++++++++++++
 include/linux/kvm_host.h |  1 +
 virt/kvm/kvm_main.c      |  4 +++-
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d21bce5..3370de1 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6904,6 +6904,20 @@ static void kvm_free_vcpus(struct kvm *kvm)
 	mutex_unlock(&kvm->lock);
 }
 
+void kvm_arch_vcpu_release(struct kvm_vcpu *vcpu)
+{
+	struct kvm *kvm = vcpu->kvm;
+
+	mutex_lock(&kvm->lock);
+	atomic_dec(&kvm->online_vcpus);
+	kvm->vcpus[atomic_read(&kvm->online_vcpus)] = NULL;
+	mutex_unlock(&kvm->lock);
+
+	kvm_clear_async_pf_completion_queue(vcpu);
+	kvm_unload_vcpu_mmu(vcpu);
+	kvm_arch_vcpu_free(vcpu);
+}
+
 void kvm_arch_sync_events(struct kvm *kvm)
 {
 	kvm_free_all_assigned_devices(kvm);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index a63d83e..e0811f97 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -631,6 +631,7 @@ struct kvm_vcpu *kvm_arch_vcpu_create(struct kvm *kvm, unsigned int id);
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu);
 int kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu);
 void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu);
+void kvm_arch_vcpu_release(struct kvm_vcpu *vcpu);
 
 int kvm_arch_hardware_enable(void *garbage);
 void kvm_arch_hardware_disable(void *garbage);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 1580dd4..442014b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1873,8 +1873,10 @@ static int kvm_vcpu_mmap(struct file *file, struct vm_area_struct *vma)
 static int kvm_vcpu_release(struct inode *inode, struct file *filp)
 {
 	struct kvm_vcpu *vcpu = filp->private_data;
+	struct kvm *kvm = vcpu->kvm;
 
-	kvm_put_kvm(vcpu->kvm);
+	kvm_arch_vcpu_release(vcpu);
+	kvm_put_kvm(kvm);
 	return 0;
 }
 
-- 
1.8.1.4

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